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*************************************************************************** *************************************************************************** The UCR Standard Library for Assembly Language Programmers, Written By Randall Hyde and others, is sssssss ss ss ss sssssss sssssss ss ss ss ssss ss ss ss ss ss ss ss ss ss ss ss sssssss sssssssss ssssssss sssssss sssss ssssssss ss ss ss ss ss ss ss ss ss ss ss ss ss ss ss ss sssssss ss ss ss ss ss ss sssssss ww ww ww sssssss sssssss ww ww wwww ss ss ss ww ww ww ww ww ss ss ss ww wwww ww wwwwwwww sssssss sssss ww ww ww ww ww ww ss ss ss wwww wwww ww ww ss ss ss ww ww ww ww ss ss sssssss We do not want any registration fees for this software. Now for the catch... It is more blessed to give than to receive. If this software saves you time and effort and you enjoy using it, our lives will be enriched knowing that others have appreciated our work. We would like to share this wonderful feeling with you. If you like this software and use it, we would like you to contribute at least one routine to the library. Perhaps you think this library has some neat-o routines in it. Imagine how nice it would become if everyone used their imagination to contribute something useful to it. We hereby release this software to the public domain. You can use it in any way you see fit. However, we would appreciate it if you share this software with others as much as it has been shared it with you. That is not to suggest that you give away software you have written with this package (We're not quite as crazy as Richard Stallman, bless his heart), but if someone else would like a copy of this library, please help them out. Naturally, we would be tickeled pink to receive credit in software that uses these routines (which is the honorable thing to do) but we understand the way many corporations operate and won't be terribly put off if you use it without giving due credit. Enjoy! If you have comments, bug reports, new code to contribute, etc., you can reach us through: rhyde (On BIX). rhyde@cs.ucr.edu (On Internet). rhyde@ucrmath.ucr.edu (Also on Internet). or Randy Hyde Dept of Computer Science 2208 Sproul Hall University of California Riverside, Ca. 92521-0135 COMMENTS ABOUT THE CODE: ************************ Please don't expect super optimal code here. Most of it is fairly mediocre (from a size/speed point of view). Hopefully, you'll agree, it's the idea that counts. If you do not like something I have done, you have got the sources -- have at it. (Of course, it would be appreciated if you would send any modifications to one of the E-MAIL addresses above.) ROUTINES WE WOULD LIKE TO HAVE: ******************************* If you're interested in adding some routines to this package, GREAT! Here are some suggestions. 1) Routines which manipulate directories (read/write/etc.) 2) A regular expression interpreter. 3) Length-prefixed strings package. 4) A graphics package. 5) An object-oriented programming class library. 6) Just about anything else appearing in a HLL "standard" library. If you've got any ideas, we would love to discuss them with you. The best way to reach us is through the E-MAIL addresses above. MISSING ROUTINES TO BE SUPPLIED IN THE FUTURE: ********************************************** Character strings: trim- Removes trailing blanks from a string. blkdel- Removes leading blanks from a string. translit- Transliterates characters in a string based on a translation table. Pattern matching and character sets: span- Skips through a sequence of characters in a string which belong to a character set. break- Skips through a sequence of characters in a string which do not belong to a character set. any- Skips over a character if it is a member of a set. notany- Skips over a character in a string if it is not a member of a set. tab- Matches upto the nth character in a string. rtab- Matches upto the nth character from the end of a string. pos- Matches if we are currently at the nth position in a string. rpos- Matches if we are at the nth position from the end of the string. mark- Marks a position in a string during pattern matching grab- Copies everything from the last mark and creates a new string on the stack from this substring. match- Initialize pattern matching system. alternate- Try an alternative if the current pattern does not match. arb- Skip over an arbitrary number of characters in a match. replace- Replace a substring from the last mark to the current position with some other string. fail- Force a match failure. succeed- Force a match success. Memory Manager Package Memavail- Largest block of free memory available on the heap. Memfree- Total amount of free space on the heap. BlockSize- Returns the size of the memory block which es:di points at. Structured Array Package aryalloc- Allocate storage for a single dimension structured array. ary2alloc- Allocate storage for a two dimension structured array. ary3alloc- Allocate storage for a three dimension structured array. arynalloc- Allocate storage for an n-dimensional structured array. aryaccess- Access an element of a structured array. ary2access- Access an element of a two-dimension structured array. ary3access- Access an element of a three-dimension structured array. arynaccess- Access an element of an n-dimensional structured array. copyarray- Copy the elements of one structured array to another. duparray- Duplicate a structured array on the heap. redim- Redimension a structured array. aryfill- Initialize an array with a list of values. cmpary- Compares two structured arrays to see if they are equal. Process Manager Package CoCall- Call a coroutine. CoInit- Initialize a coroutine. CoRet- Quit a coroutine. HOW TO USE THE STANDARD LIBRARY: ******************************** When you are ready to begin programming with the library, you should copy the shell.asm file, provided in the package, to another file in which you will be working, i.e. myprog.asm. The shell.asm file sets up the machine (segments, etc.) as the UCR Standard Library expects them. Results are undefined for other setups. Therefore, I strongly suggest, that when you begin using these routines, you follow the shell.asm format. Later, when you are familiar with the software, you may wish to create your own shell.asm file, but it is wise to initially use the one provided. The shell.asm file has comments which tell you where to place your code, variables, etc. HOW THE STANDARD LIBRARY IS ORGANIZED: ************************************** In the next several pages are the documentation spec sheets for each of the standard library routines. The routines are listed by category. The listing of the categories and their order in the documentation is below. Standard Input Routines Standard Output Routines Conversion Routines Utility Routines String Handling Routines Memory Management Routines Character Set Routines In addition, at the beginning of each of the category is a brief discussion of the purpose of its routines. Character Input Routines ------------------------ The character input routines take input from either a standard device (keyboard, etc.) or a standard library. After the character input routines receive the characters they either place the characters on the stack and/or return. The character input routines work similar to the "C" character input routines. Routine: Getc -------------- Category: Character Input Routine Registers on Entry: None Registers on Return: AL- Character from input device. AH- 0 if eof, 1 if not eof. Flags Affected: Carry- 0 if no error, 1 if error. If error occurs, AX contains DOS error code. Example of Usage: getc mov KbdChar, al putc Description: This routine reads a character from the standard input device. This call is synchronous, that is, it does not return until a character is available. The Default input device is DOS standard input. Getc returns two types of values: extended ASCII (codes 1-255) and IBM keyboard scan codes. If Getc returns a non-zero value, you may interpret this value as an ASCII character. If Getc returns zero, you must call Getc again to get the actual keypress. The second call returns an IBM PC keyboard scan code. Since the user may redirect input from the DOS command line, there is the possibility of encountering end-of-file (eof) when calling getc. Getc uses the AH register to return eof status. AH contains the number of characters actually read from the standard input device. If it returns one, then you've got a valid character. If it returns zero, you've reached end of file. Note that pressing control-z forces an end of file condition when reading data from the keyboard. This routine returns the carry flag clear if the operation was successful. It returns the carry flag set if some sort of error occurred while reading the character. Note that eof is not an error condition. Upon reaching the end of file, Getc returns with the carry flag clear. If getc is seen from a file the control-z is not seen as an end-of-file marker, but just read in as a character of the file. Control-c if read from a keyboard device aborts the program. However if when reading something other than a keyboard (files, serial ports), control-c from the input source returns control-c. However when pressing control-break the program will abort regardless of the input source. Regarding CR/LF, if the input is from a device, (eg. keyboard serail port) getc returns whatever that device driver returns, (generally CR without a LF). However if the input is from a file, getc stripes a single LF if it immediately follows the CR. When using getc the files operate in "cooked" mode. While devices operate in "pseudo-cooked" mode, which means no buffering, no CR -> CR/LF, but it handles control-c, and control-z. If reading from a file, getc calls DOS (AH = 3Fh). If reading from a device, getc calls DOS (AH = 8), it also uses IOCTL call (AX = 4400h) to determine if the input is a file or a device. Include: stdlib.a Routine: GetcStdIn -------------------- Category: Character Input Routine Register on entry: None. Register on return: AL- Character from input device. Flags affected: AH- 0 if eof, 1 if not eof. Carry- 0 if no error, 1 if error (AX contains DOS error code if error occurs). Example of Usage: GetcStdIn mov InputChr, al putc Description: This routine reads a character from the DOS standard input device. This call is synchronous, that is, it does not return until a character is available. See the description of Getc above for more details. Include: stdlib.a Routine: GetcBIOS ------------------- Category: Character Input Routine Register on entry: None Register on return: AL- Character from the keyboard. Flags affected: AH- 1 (always). Carry- 0 (always). Example of Usage: GetcBIOS mov CharRead, al mov ScanCode, ah putc Description: This routine reads a character from the keyboard. This call is synchronous, that is it does not return until a character is available. Include: stdlib.a Routine: SetInAdrs ------------------- Category: Character Input Routine Registers on Entry: ES:DI - address of new input routine Registers on return: None Flags affected: Example of Usage: mov es, seg NewInputRoutine mov di, offset NewInputRoutine SetInAdrs les di, RoutinePtr SetInAdrs Description: This routine redirects the stdlib standard input so that it calls the routine who's address you pass in es:di. This routine obtains a character (from anywhere) returns it in AL, and must preserve all registers. If it makes sense to do so, it should also return a "scan code" in the AH register. Include: stdlib.a Routine: GetInAdrs -------------------- Category: Character Input Routine Register on entry: None Register on return: ES:DI - address of current input routine (called by Getc). Flags affected: None Example of Usage: GetInAdrs mov word ptr SaveInAdrs, di mov word ptr SaveInAdrs+2, es Description: You can use this function to get the address of the current input routine, perhaps so you can save it or see if it is currently pointing at some particular piece of code. If you want to temporarily redirect the input and then restore the original input or outline, consider using PushInAdrs/PopInAdrs described later. Include: stdlib.a Routine: PushInAdrs --------------------- Category: Character Input Routine Register on entry: ES:DI - Address of new input routine. Register on return: Carry=0 if operation successful. Carry=1 if there were already 16 items on the stack. Example of Usage: mov es, seg NewInputRoutine mov di, offset NewInputRoutine PushInAdrs . . . les di, RoutinePtr PushInAdrs Description: This routine "pushes" the current input address onto an internal stack and then stores the value in es:di into the current input routine pointer. The PushInAdrs and PopInAdrs routines let you easily save and redirect the standard output and then restore the original output routine address later on. If you attempt to push more than 16 items on the stack, PushInAdrs will ignore your request and return with the carry flag set. If PushInAdrs is successful, it will return with the carry flag clear. Include: stdlib.a Routine: PopInAdrs -------------------- Category: Character Input Routine Register on entry: None Register on return: ES:DI - Points at the previous stdout routine before the pop. Example of Usage: mov es, seg NewInRoutine mov di, offset NewInputRoutine PushInAdrs . . . PopInAdrs Description: PopInAdrs undoes the effects of PushInAdrs. It pops an item off the internal stack and stores it into the input routine pointer. The previous value in the output pointer is returned in es:di. Include: stdlib.a Routine: Gets -------------- Category: Character Input Routine Register on entry: None Register on return: ES:DI - address of input of text. carry- 0 if no error, 1 if error. If error, AX contains: 0- End of file encountered in middle of string. 1- Memory allocation error. Other- DOS error code. Flags affected: None Example of usage: gets ;Read a string from the ;keyboard puts ;Print it putcr ;Print a new line free ;Deallocate storage for ;string. Description: Reads a line of text from the stdlib standard input device. Automatically allocates storage for the input string on the heap. Handles input lines up to 256 characters long. Gets reads a line of text from the stdlib standard input. It returns a pointer to a string containing each character read in the ES:DI registers. Gets calls malloc to allocate 256 bytes on the heap (plus any overhead bytes required by the memory manager system). If the user enters less than 256 bytes, gets calls realloc to free any unnecessary bytes. Gets returns all characters typed by the user except for the carriage return (ENTER) key code. Gets always returns a zero - terminated string. The action of various keys to gets depends upon where input has been directed. Generally, you can count on gets properly handling the backspace (erase previous character), escape (erase entire line), and ENTER (accept line) keys. Other keys may be active as well. For example, by default gets calls getc which calls DOS' standard input routine. If you type a control-C or break key while reading from DOS' standard input it will abort the program. If this bothers you, you can always redirect stdlib's getc routine so it calls BIOS directly rather than reading data through DOS' keyboard input routine. Note that the error condition is flagged a little differently for GETS (compared to GETC and associated routines). For GETS, eof is an error condition. If the carry flag is set and AX contains zero upon return, then GETS encountered eof somewhere in the string. ES:DI contain garbage in such a case. Note that AX is normally preserved by GETS unless an error occurs, in which case AX contains the error code. Include: stdlib.a Routine: Scanf --------------- Category: Character Input Routine Register on entry: None Register on return: None Flags affected: None Example of usage: scanf db "%i %h %^s",0 dd i, x, sptr Description: * Formatted input from stdlib standard input. * Similar to C's scanf routine. * Converts ASCII to integer, unsigned, character, string, hex, and long values of the above. Scanf provides formatted input in a fashion analogous to printf's output facilities. Actually, it turns out that scanf is considerably less useful than printf because it doesn't provide reasonable error checking facilities (neither does C's version of this routine). But for quick and dirty programs whose input can be controlled in a rigid fashion (or if you're willing to live by "garbage in, garbage out") scanf provides a convenient way to get input from the user. Like printf, the scanf routine expects you to follow the call with a format string and then a list of (far pointer) memory addresses. The items in the scanf format string take the following form: %^f, where f represents d, i, x, h, u, c, x, ld, li, lx, or lu. Like printf, the "^" symbol tells scanf that the address following the format string is the address of a (far) pointer to the data rather than the address of the data location itself. By default, scanf automatically skips any leading whitespace before attempting to read a numeric value. You can instruct scanf to skip other characters by placing that character in the format string. For example, the following call instructs scanf to read three integers separated by commas (and/or whitespace): scanf db "%i,%i,%i",0 dd i1,i2,i3 Whenever scanf encounters a non-blank character in the format string, it will skip that character (including multiple occurrences of that character) if it appears next in the input stream. Scanf always calls gets to read a new line of text from stdlib's standard input. If scanf exhausts the format list, it ignores any remaining characters on the line. If scanf exhausts the input line before processing all of the format items, it leaves the remaining variables unchanged. Scanf always deallocates the storage allocated by gets. Include: stdlib.a Character Output Routines ------------------------- The stdlib character output routines allow you to print to the standard output device. Although the processing of non-ASCII characters is undefined, most output devices handle these characters properly. In particular, they can handle return, line feed, back space, and tab. Most of the output routines in the standard library output data through the Putc routine. They generally use the AX register upon entry and print the character(s) to the standard output device by calling DOS by default. The output is redirectable to the user-written routine. However, the PutcBIOS routine prints doesn't use DOS. Instead it uses BIOS routines to print the character in AL using the INT command for teletype-like output. The print routines are similar to those in C, however, they differ in their implementation. The print routine returns to the address immediately following the terminating byte, therefore, it is important to remember to terminate your string with zero or you will print an unexpected instruction. Routine: Putc -------------- Category: Character Output Routine Registers on Entry: AL- character to output Registers on Return: None Flags affected: None Example of Usage: mov al, 'C' putc ;Prints "C" to std output. Description: Putc is the primitive character output routine. Most other output routines in the standard library output data through this procedure. It prints the ASCII character in AL register. The processing of control codes is undefined although most output routines this routine links to should be able to handle return, line feed, back space, and tab. By default, this routine calls DOS to print the character to the standard output device. The output is redirectable to to user-written routine. Include: stdlib.a Routine: PutCR --------------- Category: Character Output Routine Register on entry: None Register on return: None Flags affected: None Example of Usage: PutCR Description: Using PutCR is an easy way of printing a newline to the stdlib standard output. It prints a newline (carriage return/line feed) to the current standard output device. Include: stdlib.a Routine: PutcStdOut ------------------- Category: Character Output Routine Registers on Entry: AL- character to output Registers on Return: None Flags Affected: None Example of Usage: mov AL, 'C' PutcStdOut ; Writes "C" to standard output Description: PutcStdOut calls DOS to print the character in AL to the standard output device. Although processing of non-ASCII characters and control characters is undefined, most output devices handle these characters properly. In particular, most output devices properly handle return, line feed, back space, and tab. The output is redirectable via DOS I/O redirection. Include: stdlib.a Routine: PutcBIOS ----------------- Category: Character Output Routine Registers on Entry: AL- character to print Registers on Return: None Flags Affected: None Example of Usage: mov AL, "C" PutcBIOS Description: PutcBIOS prints the character in AL using the BIOS routines, using INT 10H/AH=14 for teletype-like output. Output through this routine cannot be redirected; such output is always sent to the video display on the PC (unless, of course, someone has patched INT 10h). Handles return, line feed, back space, and tab. Prints other control characters using the IBM Character set. Include: stdlib.a Routine: GetOutAdrs ------------------- Category: Character Output Routine Registers on Entry: None Registers on Return: ES:DI- address of current output routine (called by Putc) Flags Affected: None Example of Usage: GetOutAdrs mov word ptr SaveOutAdrs, DI mov word ptr SaveOutAdrs+2, ES Description: GetOutAdrs gets the address of the current output routine, perhaps so you can save it or see if it is currently pointing at some particular piece of code. If you want to temporarily redirect the output and then restore the original output routine, consider using PushOutAdrs/PopOutAdrs described later. Include: stdlib.a Routine: SetOutAdrs -------------------- Category: Character Output Routine Registers on Entry: ES:DI - address of new output routine Registers on return: None Flags affected: None Example of Usage: mov es, seg NewOutputRoutine mov di, offset NewOutputRoutine SetOutAdrs les di, RoutinePtr SetOutAdrs Description: This routine redirects the stdlib standard output so that it calls the routine who's address you pass in es:di. This routine expects the character to be in AL and must preserve all registers. It handles the printable ASCII characters and the four control characters return, line feed, back space, and tab. (The routine may be modified in the case that you wish to handle these codes in a different fashion.) Include: stdlib.a Routine: PushOutAdrs --------------------- Category: Character Output Routine Registers on Entry: ES:DI- Address of new output routine Registers on Return: None Flags Affected: Carry = 0 if operation is successful Carry = 1 if there were already 16 items on the stack Example of Usage: mov ES, seg NewOutputRoutine mov DI, offset NewOutputRoutine PushOutAdrs . . . les DI, RoutinePtr PushOutAdrs Description: This routine "pushes" the current output address onto an internal stack and then stores the value in es:di into the current output routine pointer. The PushOutAdrs and PopOutAdrs routines let you easily save and redirect the standard output and then restore the original output routine address later on. If you attempt to push more than 16 items on the stack, PushOutAdrs will ignore your request and return with the carry flag set. If PushOutAdrs is successful, it will return with the carry flag clear. Include: stdlib.a Routine: PopOutAdrs -------------------- Category: Character Output Routine Registers on Entry: None Registers on Return: ES:DI- Points at the previous stdout routine before the pop Flags Affected: None Example of Usage: mov ES, seg NewOutputRoutine mov DI, offset NewOutputRoutine PushOutAdrs . . . PopOutAdrs Description: PopOutAdrs undoes the effects of PushOutAdrs. It pops an item off the internal stack and stores it into the output routine pointer. The previous value in the output pointer is returned in es:di. Defaults to PutcStdOut if you attempt to pop too many items off the stack. Include: stdlib.a Routine: Puts -------------- Category: Character Output Routine Register on entry: ES:DI register - contains the address of the string Register on return: None Flags affected: None Example of Usage: les di, StrToPrt puts putcr Description: Puts prints a zero-terminated string whose address appears in es:di. Each character appearing in the string is printed verbatim. There are no special escape characters. Unlike the "C" routine by the same name, puts does not print a newline after printing the string. Use putcr if you want to print the newline after printing a string with puts. Include: stdlib.a Routine: Puth -------------- Category: Character Output Routine Register on entry: AL Register on return: AL Flags affected: None Example of Usage: mov al, 1fh puth Description: The Puth routine Prints the value in the AL register as two hexadecimal digits. If the value in AL is between 0 and 0Fh, puth will print a leading zero. This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: Putw -------------- Category: Character Output Routine Registers on Entry: AX- Value to print Registers on Return: None Flags Affected: None Example of Usage: mov AX, 0f1fh putw Description: The Putw routine prints the value in the AX register as four hexadecimal digits (including leading zeros if necessary). This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: Puti -------------- Category: Character Output Routine Registers on Entry: AX- Value to print Registers on Return: None Flags Affected: None Example of Usage: mov AX, -1234 puti Description: Puti prints the value in the AX register as a decimal integer. This routine uses the exact number of screen positions required to print the number (including a position for the minus sign, if the number is negative). This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: Putu -------------- Category: Character Output Routine Register on entry: AX register Register on return: None Flags affected: None Example of Usage: mov ax, 1234 putu Description: Putu prints the value in the AX register as a decimal integer. This routine uses the exact number of screen positions required to print the number. This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: Putl -------------- Category: Character Output Routine Register on entry: DX:AX register Register on return: None Flags affected: None Example of Usage: mov dx, 0ffffh mov ax, -1234 putl Description: Putl prints the value in the DX:AX registers as a decimal integer. This routine uses the exact number of screen positions required to print the number (including a position for the minus sign, if the number is negative). This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: Putul --------------- Category: Character Output Routine Register on entry: DX:AX register Register on return: None Flags affected: None Example of Usage: mov dx, 12h mov ax, 1234 putul Description: Putul prints the value in the DX:AX registers as a decimal integer. This routine uses the exact number of screen positions required to print the number. This routine calls the stdlib standard output routine (putc) to print all characters. Include: stdlib.a Routine: PutISize ------------------ Category: Character Output Routine Registers on Entry: AX - value to print CX - Minimum number of print positions to use Registers on return: None Flags affected: Example of Usage: mov cx, 5 mov ax, I PutISize . . . mov cx, 12 mov ax, J PutISize Description: PutISize prints the signed integer value in AX to the stdlib standard output device using a minimum of n print positions. CX contains n, the minimum field width for the output value. The number (including any necessary minus sign) is printed right justified in the output field. If the number in AX requires more print positions than specified by CX, PutISize uses however many print positions are necessary to actually print the number. If you specify zero in CX, PutISize uses the minimum number of print positions required. Of course, PutI will also use the minimum number of print positions without disturbing the value in the CX register. Note that, under no circumstances, will the number in AX ever require more than size print positions (-32,767 requires the most print positions). Include: stdlib.a Routine: PutUSize ------------------ Category: Character Output Routine Registers on entry: AX and CX Registers on return: None Flags affected: None Example of usage: mov cx, 8 mov ax, U PutUSize Description: PutUSize prints the value in AX as an unsigned decimal integer. Prints the number in a minimum field width specified by the value in CX. Like PutISize above except this one prints unsigned values. Note that the maximum number of print positions required by any number (e.g., 65,535) is five. Include: stdlib.a Routine: PutLSize ------------------ Category: Character Output Routine Register on entry: DX:AX register Register on return: None Flags affected: None Example of Usage: mov cx, 16 mov dx, word ptr L+2 mov ax, word ptr L PutLSize Description: PutLSize is similar to PutISize, except this prints the long integer value in DX:AX. Note that there may be as many as 11 print positions (e.g., -1,000,000,000). Include: stdlib.a Routine: PutULSize ------------------- Category: Character Output Routine Register on entry: AX : DX and CX Register on return: None Flags affected: None Example of usage: mov cx, 8 mov dx, word ptr UL+2 mov ax, word ptr UL PutULSize Description: Prints the value in DX:AX as a long unsigned decimal integer. Prints the number in a minimum field width specified by the value in CX. Just like PutLSize above except this one prints unsigned numbers rather than signed long integers. The largest field width for such a value is 10 print positions. Include: stdlib.a Routine: Print ---------------- Category: Character Output Routine Register on entry: CS:RET - Return address points at the string to print. Register on return: None Flags affected: None Examples of Usage: print db "Print this string to the display device" db 13,10 db "This appears on a new line" db 13,10 db 0 Description: Print lets you print string literals in a convenient fashion. The string to print immediately follows the call to the print routine. The string must contain a zero terminating byte and may not contain any intervening zero bytes. Since the print routine returns to the address immediately following the zero terminating byte, forgetting this byte or attempting to print a zero byte in the middle of a literal string will cause print to return to an unexpected instruction. This usually hangs up the machine. Be very careful when using this routine! Include: stdlib.a Routine: Printf --------------------- Category: Character Output Routine Register on entry: CS:RET - Return address points at the format string Register on return: None Flags affected: None Example of Usage: printf db "Indirect access to i: %^d",13,10,0 dd IPtr; printf db "A string allocated on the heap: %-\.32^s" db 13,10,0 dd SPtr Descriptions: Printf, like its "C" namesake, provides formatted output capabilities for the stdlib package. A typical call to printf always takes the following form: printf db "format string",0 dd operand1, operand2, ..., operandn The format string is comparable to the one provided in the "C" programming language. For most characters, printf simply prints the characters in the format string up to the terminating zero byte. The two exceptions are character prefixed by a backslash ("\") and character prefixed by a percent sign ("%"). Like C's printf, stdlib's printf uses the backslash as an escape character and the percent sign as a lead-in to a format string. Printf uses the escape character ("\") to print special characters in a fashion similar to, but not identical to C's printf. Stdlib's printf routine supports the following special characters: * r Print a carriage return (but no line feed) * n Print a new line character (carriage return/line feed). * b Print a backspace character. * t Print a tab character. * l Print a line feed character (but no carriage return). * f Print a form feed character. * \ Print the backslash character. * % Print the percent sign character. * 0xhh Print ASCII code hh, represented by two hex digits. C users should note a couple of differences between stdlib's escape sequences and C's. First, use "\%" to print a percent sign within a format string, not "%%". C doesn't allow the use of "\%" because the C compiler processes "\%" at compile time (leaving a single "%" in the object code) whereas printf processes the format string at run-time. It would see a single "%" and treat it as a format lead-in character. Stdlib's printf, on the other hand, processes both the "\" and "%" and run-time, therefore it can distinguish "\%". Strings of the form "\0xhh" must contain exactly two hex digits. The current printf routine isn't robust enough to handle sequences of the form "\0xh" which contain only a single hex digit. Keep this in mind if you find printf chopping off characters after you print a value. There is absolutely no reason to use any escape character sequences except "\0x00". Printf grabs all characters following the call to printf up to the terminating zero byte (which is why you'd need to use "\0x00" if you want to print the null character, printf will not print such values). Stdlib's printf routine doesn't care how those characters got there. In particular, you are not limited to using a single string after the printf call. The following is perfectly legal: printf db "This is a string",13,10 db "This is on a new line",13,10 db "Print a backspace at the end of this line:" db 8,13,10,0 Your code will run a tiny amount faster if you avoid the use of the escape character sequences. More importantly, the escape character sequences take at least two bytes. You can encode most of them as a single byte by simply embedding the ASCII code for that byte directly into the code stream. Don't forget, you cannot embed a zero byte into the code stream. A zero byte terminates the format string. Instead, use the "\0x00" escape sequence. Format sequences always between with "%". For each format sequence you must provide a far pointer to the associated data immediately following the format string, e.g., printf db "%i %i",0 dd i,j Format sequences take the general form "%s\cn^f" where: * "%" is always the "%" character. Use "\%" if you actually want to print a percent sign. * s is either nothing or a minus sign ("-"). * "\c" is also optional, it may or may not appear in the format item. "c" represents any printable character. * "n" represents a string of 1 or more decimal digits. * "^" is just the caret (up-arrow) character. * "f" represents one of the format characters: i, d, x, h, u, c, s, ld, li, lx, or lu. The "s", "\c", "n", and "^" items are optional, the "%" and "f" items must be present. Furthermore, the order of these items in the format item is very important. The "\c" entry, for example, cannot precede the "s" entry. Likewise, the "^" character, if present, must follow everything except the "f" character(s). The format characters i, d, x, h, u, c, s, ld, li, lx, and lu control the output format for the data. The i and d format characters perform identical functions, they tell printf to print the following value as a 16-bit signed decimal integer. The x and h format characters instruct printf to print the specified value as a 16-bit or 8-bit hexadecimal value (respectively). If you specify u, printf prints the value as a 16-bit unsigned decimal integer. Using c tells printf to print the value as a single character. S tells printf that you're supplying the address of a zero-terminated character string, printf prints that string. The ld, li, lx, and lu entries are long (32-bit) versions of d/i, x, and u. The corresponding address points at a 32-bit value which printf will format and print to the standard output. The following example demonstrates these format items: printf db "I= %i, U= %u, HexC= %h, HexI= %x, C= %c, " db "S= %s",13,10 db "L= %ld",13,10,0 dd i,u,c,i,c,s,l The number of far addresses (specified by operands to the "dd" pseudo-opcode) must match the number of "%" format items in the format string. Printf counts the number of "%" format items in the format string and skips over this many far addresses following the format string. If the number of items do not match, the return address for printf will be incorrect and the program will probably hang or otherwise malfunction. Likewise (as for the print routine), the format string must end with a zero byte. The addresses of the items following the format string must point directly at the memory locations where the specified data lies. When used in the format above, printf always prints the values using the minimum number of print positions for each operand. If you want to specify a minimum field width, you can do so using the "n" format option. A format item of the format "%10d" prints a decimal integer using at least ten print positions. Likewise, "%16s" prints a string using at least 16 print positions. If the value to print requires more than the specified number of print positions, printf will use however many are necessary. If the value to print requires fewer, printf will always print the specified number, padding the value with blanks. Printf will print the value right justified in the print field (regardless of the data's type). If you want to print the value left justified in the output file, use the "-" format character as a prefix to the field width, e.g., printf db "%-17s",0 dd string In this example, printf prints the string using a 17 character long field with the string left justified in the output field. By default, printf blank fills the output field if the value to print requires fewer print positions than specified by the format item. The "\c" format item allows you to change the padding character. For example, to print a value, right justified, using "*" as the padding character you would use the format item "%\*10d". To print it left justified you would use the format item "%-\*10d". Note that the "-" must precede the "\*". This is a limitation of the current version of the software. The operands must appear in this order. Normally, the address(es) following the printf format string must be far pointers to the actual data to print. On occasion, especially when allocating storage on the heap (using malloc), you may not know (at assembly time) the address of the object you want to print. You may have only a pointer to the data you want to print. The "^" format option tells printf that the far pointer following the format string is the address of a pointer to the data rather than the address of the data itself. This option lets you access the data indirectly. Note: unlike C, stdlib's printf routine does not support floating point output. There are two reasons for this: first, stdlib does not (yet) have a floating point library associated with it; second, adding floating point support would increase the size of printf by a tremendous amount, even if you don't use its floating point capabilities. Since most assembly language programmers don't use floating point arithmetic, I've intentionally left out floating point output. As soon as I add a floating point package to stdlib I will include floating point output. However, I will create a new routine, printf which includes floating point output. This will allow those who never use floating point I/O to keep their programs much smaller. Include: stdlib.a Conversion Routines ------------------- The stdlib conversion routines follow a uniform format of storing the data to be converted and returned. Most routines accept input and return data of either an ASCII string of characters, stored in the ES:DI register, or integers, stored in the DX:AX register. If a value is just a 16 or 8-bit value then it will be stored in AX or AL. Since there is a possibility of an error in the input values to be converted, such as it does not contain what is supposed to be converted, we use the carry flage to show error status. If the error flag is one then an error has occured and if it is zero no error occured. The routines which convert integers to strings of characters will automatically allocated storage. It allocates storage for the string on the heap via a call to the malloc routine. The string will hold the minimun number of characters required to hold the character representation of the value. It is up to the programmer to free the memory after it has been used. Routine: ATOL/ATOL2 -------------------- Category: Conversion Routine Registers on Entry: ES:DI- Points at string to convert Registers on Return: DX:AX- Long integer converted from string Flags Affected: Carry flag- Error status Examples of Usage: gets ;Get a string from user ATOL ;Convert to a value in DX:AX Description: ATOL converts the string of digits that ES:DI points at to a long (signed) integer value and returns this value in DX:AX. Note that the routine stops on the first non-digit. If the string does not begin with a digit, this routine returns zero. The only exception to the "string of digits" only rule is that the number can have a preceding minus sign to denote a negative number. Note that this routine does not allow leading spaces. ATOL2 works in a similar fashion except it doesn't preserve the DI register. That is, ATOL2 leaves DI pointing at the firsy character beyond the string of digits. ATOL/ATOL2 both return the carry flag clear if it translated the string of digits without error. It returns the carry flag set if overflow occurred. Include: stdlib.a Routine: AtoUL --------------- Category: Conversion Routine Register on entry: ES:DI (contains the address of the string to be converted) Register on return: DX:AX (contains the 32-bit unsigned integer) Flags affected: Carry flag (Carry flag = 1 if error) (Carry flag = 0 if no error) Examples of Usage: les InputString AtoUL Description: AtoUL converts the string pointed by ES:DI to a 32-bit unsigned integer. It places the 32-bit unsigned integer into the memory address pointed by DX:AX. If there is an error in conversion, the carry flag will set to one. If there is not an error, the carry flag will be set to zero. Include: stdlib.a Routine: AtoUL2 ---------------- Category: Conversion Routine Register on entry: ES:DI (contains the address of the string to be converted) Register on return: DX:AX (contains the 32-bit unsigned integer) DI (if error, DI will have the first character that is not a character) Flags affected: Carry flag (Carry = 0 if no error) (Carry = 1 if error) Example of Usage: les InputString AtoUL2 Description: AtoUL2 converts the string pointed by ES:DI to a 32-bit unsigned integer. It places the 32-bit unsigned integer into the memory address pointed by DX:AX. If there is an error in conversion, the carry flag will set to one, and DI will contain the first non-digit character in the string. If there is not an error, the carry flag will be clear. Include: stdlib.a Routine: ATOU/ATOU2 -------------------------- Category: Conversion Routine Register on entry: ES:DI points at string to convert Register on return: AX register - unsigned 16-bit integer Flags affected: carry flag - error status Example of Usage: Description: ATOU converts an ASCII string of digits, pointed to by ES:DI, to unsigned integer format. It places the unsigned 16-bit integer, converted from the string, into the AX register. ATOI works the same, except it handle unsigned 16-bit integers in the range 0..65535. Include: stdlib.a Routine: ATOH, ATOH2 -------------------- Category: Conversion Routine Registers on Entry: ES:DI- Points to string to convert Registers on Return: AX- Unsigned 16-bit integer converted from hex string DI (ATOH2)- First character beyond string of hex digits Flags Affected: Carry = Error status Example of Usage: les DI, Str2Convrt atoh ;Convert to value in AX. putw ;Print word in AX. Description: ATOH converts a string of hexadecimal digits, pointed to by ES:DI, into unsigned 16-bit numeric form. It returns the value in the AX register. If there is an error in conversion, the carry flag will set to one. If there is not an error, the carry flag will be clear. ATOH2 works the same except if an error occured DI points to the first character beyond the string of hex digits. Include: stdlib.a Routine: ATOLH, ATOLH2 ---------------------- Category: Conversion Routine Registers on Entry: ES:DI- Points to string to convert Registers on Return: DX:AX- Unsigned 32-bit integer converted from hex string DI (ATOLH2)- First character beyond string of hex digits Flags Affected: Carry = Error status Example of Usage: les DI, Str2Convrt atolh ;Convert to value in DX:AX Description: ATOLH converts a string of hexadecimal digits, pointed to by ES:DI, into unsigned 32-bit numeric form. It returns the value in the DX:AX register. If there is an error in conversion, the carry flag will set to one. If there is not an error, the carry flag will be clear. ATOLH2 works the same except if an error occured DI points to the first character beyond the string of hex digits. Include: stdlib.a Routine: ATOI --------------- Category: Conversion Routine Register on entry: ES:DI- Points at string to convert. Register on return: AX- Integer converted from string. DI (ATOI2)- First character beyond string of digits. Flags affected: Error status Examples of Usage: Description: Works just like ATOL except it translates the string to a signed 16-bit integer rather than a 32-bit long integer. Include: stdlib.a Routine ITOA ------------ Category: Conversion Routine Registers on Entry: AX- Signed 16-bit value to convert to a string Registers on Return: ES:DI- Pointer to string containing converted characters. Flags Affected: None Example of Usage: mov ax, -1234 ITOA ;Convert to string. puts ;Print it. free ;Deallocate string. Description: ITOA converts the signed integer value in AX to a string of characters which represents that value. It allocates storage for the string on the heap via a call to the malloc routine and returns a pointer to the string in ES:DI. The string contains the minimum number of characters required to hold the character representation of the value, which is always between one and six characters long. Include: stdlib.a Routine: UTOA --------------- Category: Conversion Routine Register on entry: AX - unsigned 16-bit integer to convert to a string Register on return: ES:DI register - pointer to a string containing converted characters Flags affected: None Example of Usage: mov ax, 65000 utoa puts free Description: UTOA converts a 16-bit unsigned integer value in AX to a string of characters which represents that value. It allocates storage for the string on the heap via a call to the malloc routine and returns a pointer to the string in ES:DI. The string contains the minimum number of characters required to hold the character representation of the value, which is always between one and five characters long. Include: stdlib.a Routine: HTOA --------------- Category: Conversion Routine Register on entry: AL - 8-bit integer to convert to a string Register on return: ES:DI register - pointer to a string containing converted characters Flags affected: None Description: HTOA converts an 8-bit value in AL to the two-character hexadecimal representation of that byte. It automatically allocates storage for the string on the heap via a call to the malloc routine and returns a pointer to the string in ES:DI. This routine always outputs exactly two hexadecimal digits, including a leading zero (if necessary). Include: stdlib.a Routine: WTOA -------------- Category: Conversion Routine Registers on Entry: AX- 16-bit value to convert to a string Registers on Return: ES:DI- Pointer to string containing converted characters. Flags Affected: None Example of Usage: Like HTOA above Description: WTOA converts the 16-bit value in AX to a string of four hexadecimal digits. It automatically allocates storage for the string on the heap via a call to the malloc routine and returns a pointer to the string in ES:DI. Outputs exactly four digits including leading zeros if necessary. Include: stdlib.a Routine: LtoA -------------- Category: Conversion Routine Register on entry: DX:AX (contains a signed 32 bit integer) Register on return: ES:DI (contains the address of the converted string) Flags affected: None Example of Usage: ltoa Description: LtoA converts a 32-bit signed integer pointed by DX:AX to a string pointed by ES:DI. Note: LtoA only converts from one to eleven characters. Include: stdlib.a Routine: ULTOA --------------- Category: Conversion Routine Registers on Entry: DX:AX- Unsigned 32-bit value to convert to a string Registers on Return: ES:DI- Pointer to string containing converted characters Flags Affected: None Example of Usage: Like LTOA Description: Like LTOA except this routine handles unsigned integer values. Automatically allocates storage for string converted characters. Include: stdlib.a Routine: SPrintf ----------------- Category: Conversion Routine In-Memory Formatting Routine Register on entry: CS:RET - Pointer to format string and operands of the sprintf routine Register on return: ES:DI register - pointer to a string containing output data Flags affected: None Example of Usage: sprintf db "I=%i, U=%u, S=%s",13,10,0 db i,u,s puts free Description: SPrintf is an in-memory formatting routine. It is similar to C's sprintf routine. It automatically allocates storage for the string on the heap. The programmer selects the maximum length of the output string. SPrintf works in a manner quite similar to printf, except sprintf writes its output to a string variable rather than to the stdlib standard output. Sprintf returns a pointer to the string (which is allocates on the heap) in the ES:DI registers. SPrintf, by default, allocates 2048 characters for this string and then deallocates any unnecessary storage. An external variable, sp_MaxBuf, holds the number of bytes to allocate upon entry into sprintf. If you wish to allocate more or less than 2048 bytes when calling sprintf, simply change the value of this public variable (type is word). Sprintf calls malloc to allocate the storage dynamically. You should call free to return this buffer to the heap when you are through with it. Include: stdlib.a Routine: BPrintf ------------------ Category: Conversion Routine In-Memory Formatting Routine Register on entry: CS:RET - Pointer to format string and operands of the sprintf routine ES:DI - Pointer to buffer area to store string data Register on return: None Flags affected: None Example of Usage: les di, BufferAdrs bprintf db "I=%i, U=%u, S=%s",13,10,0 db i,u,s puts Description: BPrintf works just like SPrintf except it does not automatically allocate storage for the output string. Instead, you must supply the address of an output buffer in the ES:DI registers. Include: stdlib.a Routine: SScanf ---------------- Category: Conversion Routine Formatted In-Memory Conversion Routine Registers on Entry: ES:DI - points at string containing values to convert Registers on return: None Flags affected: Example of Usage: ; this code reads the values for i, j, and s from the characters ; starting at memory location Buffer. les di, Buffer SScanf db "%i %i %s",0 dd i, j, s Description: SScanf provides formatted input in a fashion analogous to scanf. The difference is that scanf reads in a line of text from the stdlib standard input whereas you pass the address of a sequence of characters to SScanf in es:di. Include: stdlib.a Routine: ToLower ----------------- Category: Conversion Routine Register on entry: AL- Character to (possibly) convert to lower case. Register on return: AL- Converted character. Flags affected: None Example of usage: mov al, char ToLower Description: ToLower checks the character in the AL register, if it is upper case it converts it to lower case. If it is anything else, ToLower leaves the value in AL unchanged. For high performance this routine is implemented as a macro rather than as a procedure call. This routine is so short you would spend more time actually calling the routine than executing the code inside. However, the code is definitely longer than a (far) procedure call, so if space is critical and you're invoking this code several times, you may want to convert it to a procedure call to save a little space. Include: stdlib.a Routine: ToUpper ------------------ Category: Conversion Routine Registers on Entry: AL- Character to (possibly) convert to upper case Registers on Return: AL- Converted character Flags Affected: None Example of Usage: mov al, char ToUpper Description: ToUpper checks the character in the AL register, if it is lower case it converts it to upper case. If it is anything else, ToUpper leaves the value in AL unchanged. For high performance this routine is implemented as a macro rather than as a procedure call (see ToLower, above). Include: stdlib.a Utility Routines ---------------- The following 10 routines are all Utility Routines. The first routines listed below compute the number of print positions required by a 16-bit and 32-bit signed and unsigned integer value. UlSize is like the LSize except it treats the value in DX:AX as an unsigned long integer. The next set of routines in this section check the character in the AL register to see whether it is a hexidecimal digit, if it alphabetic, if it is a lower case alphabetic, if it is a upper case alphabetic, and if it is numeric. Routine: ISize --------------- Category: Utility Routine Register on entry: AX- 16-bit value to compute the output size for. Register on return: AX- Number of print positions required by this number (including the minus sign, if necessary). Flags affected: None Example of usage: mov ax, I ISize puti ;Prints positions ;req'd by I. Description: This routine computes the number of print positions required by a 16-bit signed integer value. ISize computes the minimum number of character positions it takes to print the signed decimal value in the AX register. If the number is negative, it will include space for the minus sign in the count. Include: stdlib.a Routine: USize --------------- Category: Utility Routine Register on entry: AX- 16 bit value to compute the output size for Register on return: AX- number of print positions required by this number (including the minus sign, if necessary) Flags affected: None Example of usage: mov ax, I USize puti ;prints position ;required by I Description: This routine computes the number of print positions required by a 16-bit signed integer value. It also computes the number of print positions required by a 16-bit unsigned value. USize computes the minimum number of character positions it will take to print an unsigned decimal value in the AX register. If the number is negative, it will include space for the minus sign in the count. Include: stdlib.a Routine: LSize --------------- Category: Utility Routine Register on entry: DX:AX - 32-bit value to compute the output size for. Register on return: AX - Number of print positions required by this number (including the minus sign, if necessary). Flags affected: None Example of Usage: mov ax, word ptr L mov dx, word ptr L+2 LSize puti ;Prints positions ;req'd by L. Description: This routine computes the number of print positions required by a 32-bit signed integer value. LSize computes the minimum number of character positions it will take to print the signed decimal value in the DX:AX registers. If the number is negative, it will include space for the minus sign in the count. Include: stdlib.a Routine: ULSize ---------------- Category: Utility Routine Registers on Entry: DX:AX - 32-bit value to compute the output size for. Registers on return: AX - number of print positions required by this number Flags affected: None Example of Usage: mov ax, word ptr L mov dx, word ptr L+2 ULSize puti ; Prints positions req'd by L Description: ULSize computes the minimum number of character positions it will take to print an unsigned decimal value in the DX:AX registers. Include: stdlib.a Routine: IsAlNum ----------------- Category: Utility routine Register on entry: AL - character to check. Register on return: None Flags affected: Zero flag - set if character is alpha- numeric, clear if not. Example of usage : mov al, char IsAlNum je IsAlNumChar Description : This routine checks the character in the AL register to see if it is in the range A-Z, a-z, or 0-9. Upon return, you can use the JE instruction to check to see if the character was in this range (or, conversely, you can use JNE to see if it is not in range). Include: stdlib.a Routine: IsXDigit ------------------ Category: Utility Routine Retgister on Entry: AL- character to check Registers on Return: None Flags Affected: Zero flag- Set if character is a hex digit, clear if not Example of Usage: mov al, char IsXDigit je IsXDigitChar Description: This routine checks the character in the AL register to see if it is in the range A-F, a-f, or 0-9. Upon return, you can use the JE instruction to check to see if the character was in this range (or, conversely, you can use jne to see if it is not in the range). Include: stdlib.a Routine: IsDigit ------------------ Category: Utility Routine Register on entry: AL- Character to check Register on return: Zero flag- set if character is numeric, clear if not. Flags affected: None Example of Usage: mov al, char IsDigit je IsDecChar Description: This routine checks the character in the AL register to see if it is in the range 0-9. Upon return, you can use the JE instruction to check to see if the character was in the range (or, conversely, you can use JNE to see if it is not in the range). Include: stdlib.a Routine: IsAlpha ------------------ Category: Utility Routine Register on entry: AL- Character to check Register on return: Zero flag- set if character is alphabetic, clear if not. Flags affected: None Example of Usage: mov al, char IsAlpha je IsAlChar Description: This routine checks the character in the AL register to see if it is in the range A-Z or a-z. Upon return, you can use the JE instruction to check to see if the character was in the range (or, conversely, you can use JNE to see if it is not in the range). Include: stdlib.a Routine: IsLower ---------------- Category: Utility Routine Registers on Entry: AL- character to test Registers on Return: None Flags Affected: Zero = 1 if character is a lower case alphabetic character Zero = 0 if character is not a lower case alphabetic character Example of Usage: mov AL, char ; put char in AL IsLower ; is char lower a-z? je IsLowerChar ; if yes, jump to IsLowerChar Description: This routine checks the character in the AL register to see if it is in the range a-z. Upon return, you can use the JE instruction to check and see if the character was in this range (or you can use JNE to check and see if the character was not in this range). This procedure is implemented as a macro for high performance. Include: stdlib.a Routine: IsUpper ----------------- Category: Utility Routine Registers on Entry: AL- character to check Registers on Return: None Flags Affected: Zero flag - set if character is uppercase alpha, clear if not. Example of Usage: mov al, char IsUpper je IsUpperChar Description: This routine checks the character in the AL register to see if it is in the ranger A-Z. Upon return, you can use the JE instruction to check to see if it not in the range). It uses macro implementation for high performance. Include: stdlib.a String Handling Routines ------------------------ Manipulating text is a major part of many computer applications. Typically, strings are inputed and interpreted. This interpretation may involve some chores such as extracting certain part of the text, copying it, or comparing with other strings. The string manipulation routines in C provides various functions. Therefore, the stdlib has some C-like string handling functions (e.g. strcpy, strcmp). In C a string is an array of characters; similarly, the string are terminated by a "0" as a null character. In general, the input strings of these routines are pointed by ES:DI. In some routines, the carry flag will be set to indicate an error. The file "stdlib.a" is necessary to be included and the routines are declared as extern. Routine: Strcpy, Strcpyl ------------------------- Category: String Handling Routine Registers on Entry: ES:DI - pointer to source string (Strcpy only) CS:RET - pointer to source string (Strcpy1 only) DX:SI - pointer to destination string Registers on return: ES:DI - points at the destination string Flags affected: Example of Usage: mov dx, seg target mov si, offset target Strcpy1 db "String for Strcpy1",0 ; Copy that string to ; Target2 as well, ; note that ES:DI ; already points at ; "Target". mov dx, seg Target2 mov si, offset Target2 Strcpy Description: Strcpy is used to copy a zero-terminated string from one location to another. ES:DI points at the source string, DX:SI points at the destination address. Strcpy copies all bytes, up to and including the zero byte, from the source address to the destination address. The target buffer must be large enough to hold the string. Strcpy performs no error checking on the size of the destination buffer. Strcpy1 copies the zero-terminated string immediately following the call instruction to the destination address specified by DX:SI. Again, this routine expects you to ensure that the taraget buffer is large enough to hold the result. Include: stdlib.a Routine: StrDup, StrDupl ------------------------- Category: String Handling Routine Register on entry: ES:dI - pointer to source string (StrDup only). CS:RET - Pointer to source string (StrDupl only). Register on return: ES:DI - Points at the destination string allocated on heap. Carry=0 if operation successful. Carry=0 if insufficient memory for new string. Flags affected: Carry flag Example of usage: StrDupl db "String for StrDupl",0 jc MallocError mov word ptr Dest1, di mov word ptr Dest1+2, es ;create another ;copy of this ;string. Note ;that es:di points ;at Dest1 upon ;entry to StrDup, ;but it points at ;the new string on ;exit StrDup jc MallocError mov word ptr Dest2, di mov word ptr Dest2+2, es Description: StrDup and StrDupl duplicate strings. You pass them a pointer to the string (in es:di for strdup, via the return address for strdupl) and they allocate sufficient storage on the heap for a copy of this string. Then these two routines copy their source strings to the newly allocated storage and return a pointer to the new string in ES:DI. Include: stdlib.a Routine: Strlen ---------------- Category: String Handling Routine Registers on entry: ES:DI - pointer to source string. Register on return: CX - length of specified string. Flags Affected: None Examples of Usage: les di, String strlen mov sl, cx printf db "Length of '%s' is %d\n",0 dd String, sl Description: Strlen computes the length of the string whose address appears in ES:DI. It returns the number of characters up to, but not including, the zero terminating byte. Include: stdlib.a Routine: Strcat, Strcat2, Strcatl, Strcat2l -------------------------------------------- Category: String Handling Routine Registers on Entry: ES:DI- Pointer to first string DX:SI- Pointer to second string (Strcat and Strcat2 only) Registers on Return: ES:DI- Pointer to new string (Strcat2 and Strcat2l only) Flags Affected: Carry = 0 if no error Carry = 1 if insufficient memory (Strcat2 and Strcat2l only) Example of Usage: les DI, String1 mov DX, seg String2 lea SI, String2 Strcat ; String1 <- String1 + String2 les DI, String1 Strcatl ; String1 <- String1 + db "Appended String",0 ; "Appended String",0 les DI, String1 mov DX, seg String2 lea SI, String2 Strcat2 ; NewString <- String1 + String2 puts free les DI, String1 Strcat2l ; NewString <- String1 + db "Appended String",0 ; "Appended String",0 puts free Description: These routines concatenate two strings together. They differ mainly in the location of their source and destination operands. Strcat concatenates the string pointed at by DX:SI to the end of the string pointed at by ES:DI in memory. Both strings must be zero-terminated. The buffer pointed at by ES:DI must be large enough to hold the resulting string. Strcat does NOT perform bounds checking on the data. ( continued on next page ) Routine: Strcat, Strcat2, Strcatl, Strcat2l ( continued ) -------------------------------------------- Strcat2 computes the length of the two strings pointed at by ES:DI and DX:SI and attempts to allocate this much storage on the heap. If it is not successful, Strcat2 returns with the Carry flag set, otherwise it copies the string pointed at by ES:DI to the heap, concatenates the string DX:SI points at to the end of this string on the heap, and returns with the Carry flag clear and ES:DI pointing at the new (concatenated) string on the heap. Strcatl and Strcat2l work just like Strcat and Strcat2 except you supply the second string as a literal constant immediately AFTER the call rather than pointing DX:SI at it (see examples above). Include: stdlib.a Routine: Strchr ---------------- Category: String Handling Routine Register on entry: ES:DI- Pointer to string. AL- Character to search for. Register on return: CX- Position (starting at zero) where Strchr found the character. Flags affected: Carry=0 if Strchr found the character. Carry=1 if the character was not present in the string. Example of usage: les di, String mov al, Char2Find Strchr jc NotPresent mov CharPosn, cx Description: Strchr locates the first occurrence of a character within a string. It searches through the zero-terminated string pointed at by es:di for the character passed in AL. If it locates the character, it returns the position of that character to the CX register. The first character in the string corresponds to the location zero. If the character is not in the string, Strchr returns the carry flag set. CX's value is undefined in that case. If Strchr locates the character in the string, it returns with the carry clear. Include: stdlib.a Routine: Strstr, Strstrl ------------------------- Category: String Handling Routine Register on entry: ES:DI - Pointer to string. DX:SI - Pointer to substring(strstr). CS:RET - Pointer to substring (strstrl). Register on return: CX - Position (starting at zero) where Strstr/Strstrl found the character. Carry=0 if Strstr/ Strstrl found the character. Carry=1 if the character was not present in the string. Flags affected: Carry flag Example of usage : les di, MainString lea si, Substring mov dx, seg Substring Strstr jc NoMAtch mov i, cx printf db "Found the substring '%s' at location %i\n",0 dd Substring, i jmp Done Description: Strstr searches for the position of a substring within another string. ES:DI points at the string to search through, DX:SI points at the substring. Strstr returns the index into ES:DI's string where DX:SI's string is found. If the string is found, Strstr returns with the carry flag clear and CX contains the (zero based) index into the string. If Strstr cannot locate the substring within the string ES:DI points at, it returns the carry flag set. Strstrl works just like Strstr except it excepts the substring to search for immediately after the call instruction (rather than passing this address in DX:SI). Include: stdlib.a Routine: Strcmp ---------------- Category: String Handling Routine Registers on entry: ES:DI (contains the address of the first string) DX:SI (contains the address of the second string) Register on return: CX (contains the position where the two strings differ) Flags affected: Carry flag and zero flag (string1 > string2 if C + Z = 0) (string1 < string2 if C = 1) Example of Usage: les di, String1 mov dx, seg String2 lea si, String2 strcmp Description: Strcmp compares the first strings pointed by ES:DI with the second string pointed by DX:SI. The carry and zero flag will contain the corresponding result. So unsigned branch instructions such as JA or JB is recommended. If string1 equals string2, strcmp will return with CX containing the offset of the zero byte in the two strings. Include: stdlib.a Routine: Strcmpl ---------------- Category: String Handling Routine Registers on entry: ES:DI (contains the address of the first string) CS:RET (contains the address of the substring) Registers on return: CX (contains the position where two strings differ) Flags affected: Carry flag and zero flag (string1 > string2 if C + Z = 0) (string1 < string2 if C = 1) Example of Usage: les di, String1 strcmpl db "Hello",0 jbe elsewhere Description: Strcmpl compares the first string pointed by ES:DI with the substring pointed by CS:RET. The carry and zero flag will contain the corresponding result. So unsigned branch instructions such as JA or JB is recommended. If string1 equals to the substring, strcmp will return with CX containing the offset of the zero byte in the two strings. Include: stdlib.a Routine: Strupr ---------------- Category: String Handling Routine Conversion Routine Register on entry: ES:DI (contains the pointer to input string) Register on return: ES:DI (contains the pointer to input string with characters converted to upper case) Flags affected: None Example of Usage: les di, lwrstr1 strupr print Description: Strupr converts the input string pointed by ES:DI to upper case. It will actually modify the string you pass to it. Include: stdlib.a Routine: Strupr2 ----------------- Category: String Handling Routine Conversion Routine Register on entry: ES:DI (contains the pointer to input string) Register on return: ES:DI (contains the pointer to newly created string) Flags affected: Carry flag (Carry = 0 if no error) (Carry = 1 if error) Example of Usage: les di, lwrstr1 strupr2 Description: Strupr2 calls Strdup to copy the input string to a new string, and converts the new string to upper case. ES:DI will contain the pointer to the new string on return. If there is an error in allocating space for the new string, the carry flag will set to 1; otherwise, it will remain 0. Include: stdlib.a Routine: Strlwr ---------------- Category: String Handling Routine Conversion Routine Register on entry: ES:DI (contains the pointer to input string) Register on return: ES:DI (contains the pointer to input string with characters converted to lower case). Flags affected: None Example of Usage: les di, uprstr1 strlwr print Description: Strlwr converts the input string pointed by ES:DI to lower case. It will actually modify the string you pass to it. Include: stdlib.a Routine: Strlwr2 ----------------- Category: String Handling Routine Conversion Routine Register on entry: ES:DI (contains the pointer to input string) Register on return: ES:DI (contains the pointer to newly created string) Flags affected: Carry flag (Carry = 0 if no error) (Carry = 1 if error) Example of Usage: les di, uprstr1 strlwr2 Description: Strlwr2 calls Strdup to copy the input string to a new string, and converts the new string to lower case. ES:DI will contain the pointer to the new string on return. If there is an error in allocating memory for the new string, the carry flag will set to 1; otherwise, it will remain 0. Include: stdlib.a Routine: Strset ---------------- Category: String Handling Routine Register on entry: ES:DI (contains the pointer to input string) AL (contains the character to copy) Register on return: None Flags affected: None Example of Usage: les di, string1 Strset Description: Strset overwrites the data on input string pointed by ES:DI with the character on AL. Include: stdlib.a Routine: Strset2 ----------------- Category: String Handling Routine Register on entry: AL (contains the character to copy) CX (contains the number of characters to copy) Register on return: ES:DI (contains the pointer to new string) Flags affected: Carry flag (Carry = 0 if no error) (Carry = 1 if error) Example of Usage: mov al,'#' mov cx, 5 strset2 puts Description: Strset2 calls Malloc to allocate space for the new string and initializes it with the character in AL. If there is an error from malloc, the carry will set to one; otherwise, it will set to zero. Include: stdlib.a Routine: Strspan, Strspanl --------------------------- Category: String Handling Routine Registers on Entry: ES:DI - Pointer to string to scan DX:SI - Pointer to character set (Strspan only) CS:RET- Pointer to character set (Strspanl only) Registers on Return: CX- First position in scanned string which does not contain one of the characters in the character set Flags Affected: None Example of Usage: les DI, String mov DX, seg CharSet lea SI, CharSet Strspan ; find first position in String with a mov i, CX ; char not in CharSet printf db "The first char which is not in CharSet " db "occurs at position %d in String.\n",0 dd i les DI, String db "aeiou",0 Strspanl ; find first position in String which mov j, CX ; is not a vowel printf db "The first char which is not a vowel " db "occurs at position %d in String.\n",0 dd j Description: Strspan(l) scans a string, counting the number of characters which are present in a second string (which represents a character set). ES:DI points at a zero-terminated string of characters to scan. DX:SI (strspan) or CS:RET (strspanl) points at another zero- terminated string containing the set of characters to compare against. The position of the first character in the string pointed to by ES:DI which is NOT in the character set is returned. If all the characters in the string are in the character set, the position of the zero-terminating byte will be returned. Although strspan and (especially) strspanl are very compact and convenient to use, they are not particularly efficient. The character set routines provide a much faster alternative at the expense of a little more space. Include: stdlib.a Routine: Strcspan, Strcspanl ----------------------------- Category: String Handling Routine Registers on Entry: ES:DI - Pointer to string to scan DX:SI - Pointer to character set (Strcspan only) CS:RET- Pointer to character set (Strcspanl only) Registers on Return: CX- First position in scanned string which contains one of the characters in the character set Flags Affected: None Example of Usage: les DI, String mov DX, seg CharSet lea SI, CharSet Strcspan ; find first position in String with a mov i, CX ; char in CharSet printf db "The first char which is in CharSet " db "occurs at position %d in String.\n",0 dd i les DI, String db "aeiou",0 Strcspanl ; find first position in String which mov j, CX ; is a vowel printf db "The first char which is a vowel occurs " db "at position %d in String.\n",0 dd j Description: Strcspan(l) scans a string, counting the number of characters which are NOT present in a second string (which represents a character set). ES:DI points at a zero-terminated string of characters to scan. DX:SI (strcspan) or CS:RET (strcspanl) points at another zero-terminated string containing the set of characters to compare against. The position of the first character in the string pointed to by ES:DI which is in the character set is returned. If all the characters in the string are not in the character set, the position of the zero-terminating byte will be returned. Although strcspan and strcspanl are very compact and convenient to use, they are not particularly efficient. The character set routines provide a much faster alternative at the expense of a little more space. Include: stdlib.a Routine: StrIns, StrIns2, StrInsl, StrIns2l -------------------------------------------- Category: String Handling Routine Registers on Entry: ES:DI - Pointer to destination string (to insert into) DX:SI - Pointer to string to insert (StrIns and StrIns2 only) CX - Insertion point in destination string Registers on Return: ES:DI - Pointer to new string (StrIns2 and StrIns2l only) Flags Affected: Carry = 0 if no error Carry = 1 if insufficient memory (StrIns2 and StrIns2l only) Example of Usage: les DI, DestStr mov DX, word ptr SrcStr+2 mov SI, word ptr SrcStr mov CX, 5 StrIns ; Insert SrcStr before the 6th char of DestStr les DI, DestStr mov CX, 2 StrInsl ; Insert "Hello" before the 3rd char of DestStr db "Hello",0 les DI, DestStr mov DX, word ptr SrcStr+2 mov SI, word ptr SrcStr mov CX, 11 StrIns2 ; Create a new string by inserting SrcStr ; before the 12th char of DestStr puts putcr Description: These routines insert one string into another string. ES:DI points at the string into which you want to insert another. CX contains the position (or index) where you want the string inserted. This index is zero-based, so if CX contains zero, the source string will be inserted before the first character in the destination string. If CX contains a value larger than the size of the destination string, the source string will be appended to the destination string. StrIns inserts the string pointed at by DX:SI into the string pointed at by ES:DI at position CX. The buffer pointed at by ES:DI must be large enough to hold the resulting string. StrIns does NOT perform bounds checking on the data. ( continued on next page ) Routine: StrIns, StrIns2, StrInsl, StrIns2l ( continued ) -------------------------------------------- StrIns2 does not modify the source or destination strings, but instead attempts to allocate a new buffer on the heap to hold the resulting string. If it is not successful, StrIns2 returns with the Carry flag set, otherwise the resulting string is created and its address is returned in the ES:DI registers. StrInsl and StrIns2l work just like StrIns and StrIns2 except you supply the second string as a literal constant immediately AFTER the call rather than pointing DX:SI at it (see examples above). Routine: StrDel, StrDel2 ------------------------- Category: String Handling Routine Registers on Entry: ES:DI - pointer to string CX - deletion point in string AX - number of characters to delete Registers on return: ES:DI - pointer to new string (StrDel2 only) Flags affected: Carry = 1 if memory allocation error, 0 if okay (StrDel2 only). Example of Usage: les di, Str2Del mov cx, 3 ; Delete starting at 4th char mov ax, 5 ; Delete five characters StrDel ; Delete in place les di, Str2Del2 mov cx, 5 mov ax, 12 StrDel2 puts free Description: StrDel deletes characters from a string. It works by computing the beginning and end of the deletion point. Then it copies all the characters from the end of the deletion point to the end of the string (including the zero byte) to the beginning of the deletion point. This covers up (thereby effectively deleting) the undesired characters in the string. Here are two degenerate cases to worry about -- 1) when you specify a deletion point which is beyond the end of the string; and 2) when the deletion point is within the string but the length of the deletion takes you beyond the end of the string. In the first case StrDel simply ignores the deletion request. It does not modify the original string. In the second case, StrDel simply deletes everything from the deletion point to the end of the string. StrDel2 works just like StrDel except it does not delete the characters in place. Instead, it creates a new string on the heap consisting of the characters up to the deletion point and those following the characters to delete. It returns a pointer to the new string on the heap in ES:DI, assuming that it properly allocated the storage on the heap. Include: stdlib.a Routine: StrRev, StrRev2 ------------------------- Author: Michael Blaszczak (.B ekiM) Category: String Handling Routine Registers on Entry: ES:DI - pointer to string Registers on return: ES:DI - pointer to new string (StrRev2 only). Flags affected: Carry = 1 if memory allocation error, 0 if okay (StrRev2 only). Example of Usage: Description: StrRev reverses the characters in a string. StrRev reverses, in place, the characters in the string that ES:SI points at. StrRev2 creates a new string on the heap (which contains the characters in the string ES:DI points at, only reversed) and returns a pointer to the new string in ES:DI. If StrRev2 cannot allocate sufficient memory for the string, it returns with the carry flag set. Include: stdlib.a Memory Management Routines -------------------------- The stdlib memory management routines let you dynamically allocate storage on the heap. These routines are somewhat similar to those provided by the "C" programming language. However, these routines do not perform garbage collection, as this would introduce too many restrictions and have a very adverse effect on speed. The following paragraph gives a description of how the memory management routines work. These routines may be updated in future revisions, however, so you should never make assumptions about the structure of the memory management record (described below) or else your code may not work on the next revision. The allocation/deallocation routines should be fairly fast. Malloc and free use a modified first/next fit algorithm which lets the system quickly find a memory block of the desired size without undue fragmentation problems (average case). The memory manager data structure has an overhead of eight bytes (meaning each malloc operation requires at least eight more bytes than you ask for) and a granularity of 16 bytes. The overhead (eight bytes) per allocated block may seem rather high, but that is part of the price to pay for faster malloc and free routines. All pointers are far pointers and each new item is allocated on a paragraph boundary. The current memory manager routines always allocate (n+8) bytes, rounding up to the next multiple of 16 if the result is not evenly divisible by sixteen. The first eight bytes of the structure are used by the memory management routines, the remaining bytes are available for use by the caller (malloc, et. al., return a pointer to the first byte beyond the memory management overhead structure). Routine: MemInit ----------------- Category: Memory Management Routine Registers on Entry: DX - number of paragraphs to reserve Globals Affected: zzzzzzseg - segment name of the last segment in your program PSP - public word variable which holds the PSP value for your program Registers on return: CX - number of paragraphs actually reserved by MemInit Flags affected: Carry = 0 if no error. Carry = 1 if error; AX contains DOS error code. Example of Usage: ; Don't forget to set up PSP ; and zzzzzzseg before calling ; MemInit mov dx, dx ; Allocate all available RAM MemInit jc MemoryError ; CX contains the number of ; paragraphs actually ; allocated Description: This routine initializes the memory manager system. You must call it before using any routines which call any of the memory manager procedures (since a good number of the stdlib routines call the memory manager, you should get in the habit of always calling this routine.) The system will "die a horrible death" if you call a memory manager routine (like malloc) without first calling MemInit. This routine expects you to define (and set up) two global names: zzzzzzseg and PSP. "zzzzzzseg" is a dummy segment which must be the name of the very last segment defined in your program. MemInit uses the name of this segment to determine the address of the last byte in your program. If you do not declare this segment last, the memory manager will overwrite anything which follows zzzzzzseg. The "shell.asm" file provides you with a template for your programs which properly defines this segment. PSP should be a word variable which contains the program segment prefix value for your program. MS-DOS passes the PSP value to your program in the DS and ES registers. You should save this value in the PSP variable. Don't forget to make PSP a public symbol in your main program's source file. The "shell.asm" file demonstrates how to properly set up this value. The DX register contnains the number of 16-byte paragraphs you want to reserve for the heap. If DX contains zero, MemInit will allocate all of the available memory to the heap. If your program is going to allow the user to run a copy of the command interpreter, or if your program is going to EXEC some other program, you should not allocate all storage to the heap. Instead, you should reserve some memory for those programs. By setting DX to some value other than zero, you can tell MemInit how much memory you want to reserve for the heap. All left over memory will be available for other system (or program) use. If the value in DX is larger than the amount of available RAM, MemInit will split the available memory in half and reserve half for the heap leaving the other half unallocated. If you want to force this situation (to leave half available memory for other purposes), simply load DX with 0FFFFH before calling MemInit. There will never be this much memory available, so this will force MemInit to split the available RAM between the heap and unallocated storage. On return from MemInit, the CX register contains the number of paragraphs actually allocated. You can use this value to see if MemInit has actually allocated the number of paragraphs you requested. You can also use this value to determine how much space is available when you elect to split the free space between the heap and the unallocated portions. If all goes well, this routine returns the carry flag clear. If a DOS memory manager error occurs, this routine returns the carry flag set and the DOS error code in the AX register. Include: stdlib.a Routine: Malloc ---------------- Category: Memory Management Routine Registers on Entry: CX - number of bytes to reserve Registers on return: CX - number of bytes actually reserved by Malloc ES:DI - ptr to 1st byte of memory allocated by Malloc Flags affected: Carry=0 if no error. Carry=1 if insufficient memory. Example of Usage: mov cx, 256 Malloc jnc GoodMalloc print db "Insufficient memory to continue.",cr,lf,0 jmp Quit GoodMalloc: mov es:[di], 0 ;Init string to NULL Description: Malloc is the workhorse routine you use to allocate a block of memory. You give it the numbmer of bytes you need and if it finds a block large enough, it will allocate the requested amount and return a pointer to that block. Most memory managers require a small amount of overhead for each block they allocate. Stdlib's (current) memory manager requires an overhead of eight bytes. Furthermore, the grainularity is 16 bytes. This means that Malloc always allocates blocks of memory in paragraph multiples. Therefore, Malloc may actually reserve more storage than you specify. Therefore, the value returned in CX may be somewhat greater than the requested value. By setting the minimum allocationn size to a paragraph, however, the overhead is reduced and the speed of Malloc is improved by a considerable amount. Stdlib's memory management does not do any garbage collection. Doing so would place too many demands on Malloc's users. Therefore, it is quite possible for you to fragment memory with multiple calls to maloc, realloc, and free. You could wind up in a situation where there is enough free memory to satisfy your request, but there isn't a single contiguous block large enough for the request. Malloc treats this as an insufficient memory error and returns with the carry flag set. If Malloc cannot allocate a block of the requested size, it returns with the carry flag set. In this situation, the contents of ES:DI is undefined. Attempting to dereference this pointer will produce erratic and, perhaps, disasterous results. Include: stdlib.a Routine: Realloc ----------------- Category: Memory Management Routine Registers on Entry: CX - number of bytes to reserve ES:DI - pointer to block to reallocate. Registers on return: CX - number of bytes actually reserved by Realloc. ES:DI - pointer to first byte of memory allocated by Realloc. Flags affected: Carry = 0 if no error. Carry = 1 if insufficient memory. Example of Usage: Description: Realloc lets you change the size of an allocated block in the heap. It allows you to make the block larger or smaller. If you make the block smaller, Realloc simply frees (returns to the heap) any leftover bytes at the end of the block. If you make the block larger, Realloc goes out and allocates a block of the requested size, copies the bytes form the old block to the beginning of the new block (leaving the bytes at the end of the new block uninitialized)), and then frees the old block. Include: stdlib.a Routine: Free -------------- Category: Memory Management Routine Registers on Entry: ES:DI - pointer to block to deallocate Registers on return: None Flags affected: Carry = 0 if no error. Carry = 1 if ES:DI doesn't point at a Free block. Example of Usage: les di, HeapPtr Free Description: Free (possibly) deallocates storage allocated on the heap by malloc or Realloc. Free returns this storage to heap so other code can reuse it later. Note, however, that Free doesn't always return storage to the heap. The memory manager data structure keeps track of the number of pointers currently pointing at a block on the heap (see DupPtr, below). If you've set up several pointers such that they point at the same block, Free will not deallocate the storage until you've freed all of the pointers which point at the block. Free usually returns an error code (carry flag = 1) if you attempt to Free a block which is not currently allocated or if you pass it a memory address which was not returned by malloc (or Realloc). By no means is this routine totally robust. If you start calling free with arbitrary pointers in es:di (which happen to be pointing into the heap) it is possible, under certain circumstances, to confuse Free and it will attempt to free a block it really should not. This problem could be solved by adding a large amount of extra code to the free routine, but it would slow it down considerably. Therefore, a little safety has been sacrificed for a lot of speed. Include: stdlib.a Routine: DupPtr ---------------- Category: Memory Manager Routine Registers on Entry: ES:DI - pointer to block Registers on return: None Flags affected: Carry = 0 if no error. Carry = 1 if es:di doesn't point at a free block. Example of Usage: les di, Ptr DupPtr Description: DupPtr increments the pointer count for the block at the specifiied address. Malloc sets this counter to one. Free decrements it by one. If free decrements the value and it becomes zero, free will release the storage to the heap for other use. By using DupPtr you can tell the memory manager that you have several pointers pointing at the same block and that it shouldn't deallocate the storage until you free all of those pointers. Include: stdlib.a Routine: IsInHeap ------------------ Category: Memory Management Routine Registers on Entry: ES:DI - pointer to a block Registers on return: None Flags affected: Carry = 0 if ES:DI is a valid pointer. Carry = 1 if not. Example of Usage: Description: This routine lets you know if es:di contains the address of a byte in the heap somewhere. It does not tell you if es:di contains a valid pointer returned by malloc (see IsPtr, below). For example, if es:di contains the address of some particular element of an array (not necessarily the first element) allocated on the heap, IsInHeap will return with the carry clear denoting that the es:di points somewhere in the heap. Keep in mind that calling this routine does not validate the pointer; it could be pointing at a byte which is part of the memory manager data structure rather than at actual data (since the memory manager maintains that informatnion within the bounds of the heap). This routine is mainly useful for seeing if something is allocated on the heap as opposed to somewhere else (like your code, data, or stack segment). Include: stdlib.a Routine: IsPtr --------------- Category: Memory Management Routine Registers on Entry: ES:DI - pointer to block Registers on return: None Flags affected: Carry = 0 if es:di is a valid pointer. Carry = 1 if not. Example of Usage: Description: IsPtr is much more specific than IsInHeap. This routine returns the carry flag clear if and only if es:di contains the address of a properly allocated (and currently allocated) block on the heap. This pointer must be a value returned by Malloc, Realloc, or DupPtr and that block must be currently allocated for IsPtr to return the carry flag clear. Include: stdlib.a Character Set Routines ---------------------- The character set routines let you deal with groups of characters as a set rather than a string. A set is an unordered collection of objects where membership (presence or absence) is the only important quality. The stdlib set routines were designed to let you quickly check if an ASCII character is in a set, to quickly add characters to a set or remove characters from a set. These operations are the ones most commonly used on character sets. The other operations (like union, intersection, difference, etc.) are useful, but are not as popular as the former routines. Therefore, the data structure has been optimized for sets to handle the membership and add/delete operations at the slight expense of the others. Character sets are implemented via bit vectors. A "1" bit means that an item is present in the set and a "0" bit means that the item is absent from the set. The most common implementation of a character set is to use thirty-two consecutive bytes, eight bytes per, giving 256 bits (one bit for each char- acter in the character set). While this makes certain operations (like assignment, union, intersection, etc.) fast and convenient, other operations (membership, add/remove items) run much slower. Since these are the more important operations, a different data structure is used to represent sets. A faster approach is to simply use a byte value for each item in the set. This offers a major advantage over the thirty-two bit scheme: for operations like membership it is very fast (since all you have got to do is index into an array and test the resulting value). It has two drawbacks: first, oper- ations like set assignment, union, difference, etc., require 256 operations rather than thirty-two; second, it takes eight times as much memory. The first drawback, speed, is of little consequence. You will rarely use the the operations so affected, so the fact that they run a little slower will be of little consequence. Wasting 224 bytes is a problem, however. Especially if you have a lot of character sets. The approach used here is to allocate 272 bytes. The first eight bytes con- tain bit masks, 1, 2, 4, 8, 16, 32, 64, 128. These masks tell you which bit in the following 264 bytes is associated with the set. This facilitates putting eight sets into 272 bytes (34 bytes per character set). This provides almost the speed of the 256-byte set with only a two byte overhead. In the stdlib.a file there is a macro that lets you define a group of character sets: set. The macro is used as follows: set set1, set2, set3, ... , set8 You must supply between one and eight labels in the operand field. These are the names of the sets you want to create. The set macro automatically attaches these labels to the appropriate mask bytes in the set. The actual bit patterns for the set begin eight bytes later (from each label). There- fore, the byte corresponding to chr(0) is staggered by one byte for each set (which explains the other eight bytes needed above and beyond the 256 required for the set). When using the set manipulation routines, you should always pass the address of the mask byte (i.e., the seg/offset of one of the labels above) to the particular set manipulation routine you are using. Passing the address of the structure created with the macro above will reference only the first set in the group. Note that you can use the set operations for fast pattern matching appli- cations. The set membership operation for example, is much faster that the strspan routine found in the string package. Proper use of character sets can produce a program which runs much faster than some of the equivalent string operations. Routine: Createsets -------------------- Category: Character Set Routine Registers on Entry: no parameters passed Registers on return: ES:DI - pointer to eight sets Flags affected: Carry = 0 if no error. Carry = 1 if insufficient memory to allocate storage for sets. Example of Usage: Createsets jc NoMemory mov word ptr SetPtr, di mov word ptr SetPtr+2, es Description: Createsets allocates 272 bytes on the heap. This is sufficient room for eight character sets. It then initializes the first eight bytes of this storage with the proper mask values for each set. Location es:0[di] gets set to 1, location es:1[di] gets 2, location es:2[di] gets 4, etc. The Createsets routine also initializes all of the sets to the empty set by clearing all the bits to zero. Include: stdlib.a Routine: EmptySet ------------------ Category: Character Set Routine Registers on Entry: ES:DI - pointer to first byte of desired set Registers on return: None Flags affected: Example of Usage: les di, SetPtr add di, 3 ; Point at 4th set in group. Emptyset Description: Emptyset clears out the bits in a character set to zero (thereby setting it to the empty set). Upon entry, es:di must point at the first byte of the character set you want to clear. Note that this is not the address returned by Createsets. The first eight bytes of a character set structure are the addresses of eight different sets. ES:DI must point at one of these bytes upon entry into Emptyset. Include: stdlib.a Routine: Rangeset ------------------ Category: Character Set Routine Registers on entry: ES:DI (contains the address of the first byte of the set) AL (contains the lower bound of the items) AH (contains the upper bound of the items) Registers on return: None Flags affected: None Example of Usage: lea di, SetPtr add di, 4 mov al, 'A' mov ah, 'Z' rangeset Description: This routine is to add a range of a set with ES:DI as the pointer of the set, AL as the lower bound of the set, and AH as the upper bound of the set (AH has to be greater than AL, otherwise, there will an error). Include: stdlib.a Routine: Addstr, Addstrl ------------------------- Category: Character Set Routine Registers on Entry: ES:DI- pointer to first byte of desired set DX:SI- pointer to string to add to set (Addstr only) CS:RET-pointer to string to add to set (Addstrl only) Registers on Return: None Flags Affected: None Example of Usage: les di, SetPtr add di, 1 ;Point at 2nd set in group. mov dx, seg CharStr ;Pointer to string lea si, CharStr ; chars to add to set. addstr ;Union in these characters. ; les di, SetPtr ;Point at first set in group. addstrl db "AaBbCcDdEeFf0123456789",0 ; Description: Addstr lets you add a group of characters to a set by specifying a string containing the characters you want in the set. To Addstr you pass a pointer to a zero-terminated string in dx:si. Addstr will add (union) each character from this string into the Include: stdlib.a Routine: Rmvstr ---------------- Category: Character Set Routine Registers on entry: ES:DI (contains the address of first byte of a set) DX:SI (contains the address of string to be removed from a set) Registers on return: None Flags affected: None Example of Usage: lea di, SetPtr add di, 1 mov dx, seg CharStr lea si, CharStr rmstr Description: This routine is to remove a string from a set with ES:DI pointing to its first byte, and DX:SI pointing to the string to be removed from the set. Include: stdlib.a Routine: AddChar ----------------- Category: Character Set Routine Registers on Entry: ES:DI- pointer to first byte of desired set AL- character to add to the set Registers on Return: None Flags affected: None Example of Usage: les di, SetPtr add di, 1 ;Point at 2nd set in group. mov al, Ch2Add ;Character to add to set. addchar Description: AddChar lets you add a single character (passed in AL) to a set. Include: stdlib.a Routine: Rmvchar ----------------- Category: Character Set Routine Registers on entry: ES:DI (contains the address of first byte of a set) AL (contains the character to be removed) Registers on return: None Flags affected: Zero flag (Zero = 1 if the character is in the set Zero = 0 if the character is not in the set) Example of Usage: lea di, SetPtr add di, 7 mov al, Ch2Chk member je IsInSet Description: This routine is to remove a character in AL from a set. ES:SI points to its mask byte. If the character is in the set, the zero flag is set to 1. If not, it is set to zero. Include: stdlib.a Routine: Member ---------------- Category: Character Set Routine Registers on entry: ES:DI (contains the address of first byte of a set) AL (contains the character to be compared) Registers on return: None Flags affected: Zero flag (Zero = 1 if the character is in the set Zero = 0 if the character is not in the set) Example of Usage: les di, SetPtr add di, 1 mov al, 'H' member je IsInSet Description: Member is used to find out if a character in AL is in a set with ES:DI pointing to its mask byte. If the character is in the set, the zero flag is set to 1. If not, the zero flag is set to zero. Include: stdlib.a Routine: CopySet ----------------- Category: Character Set Routine Register on entry: ES:DI- pointer to first byte of destination set. DX:SI- pointer to first bye of source set. Register on Return: None Flags affected: None Example of Usage: les di, SetPtr add di, 7 ;Point at 8th set in group. mov dx, seg SetPtr2 ;Point at first set in group. lea si, SetPtr2 copyset Description: CopySet copies the items from one set to another. This is a straight assignment, not a union operation. After the operation, the destination set is identical to the source set, both in terms of the element present in the set and absent from the set. Include: stdlib.a Routine: SetUnion ------------------ Category: Character Set Routine Register on entry: ES:DI - pointer to first byte of destination set. DX:SI - pointer to first byte of source set. Register on return: None Flags affected: None Example of Usage: les di, SetPtr add di, 7 ;point at 8th set in group. mov dx, seg SetPtr2 ;point at 1st set in group. lea si, sSetPtr2 unionset ; Description: The SetUnion routine computes the union of two sets. That is, it adds all of the items present in a source set to a destination set. This operation preserves items present in the destination set before the SetUnion operation. Include: stdlib.a Routine: SetIntersect ---------------------- Category: Character Set Routine Register on entry: ES:DI - pointer to first byte of destination set. DX:SI - pointer to first byte of source set. Register on return: None Flags affected: None Example of Usage: les di, SetPtr add di, 7 ;point at 8th set in group. mov dx, seg SetPtr2 ;point at 1st set in group. lea si, SetPtr2 setintersect Description: SetIntersect computes the intersection of two sets, leaving the result in the destination set. The new set consists only of those items which previously appeared in both the source and destination sets. Include: stdlib.a Routine: SetDifference ----------------------- Category: Character Set Routine Register on entry: ES:DI - pointer to the first byte of destination set. DX:SI - pointer to the first byte of the source set. Register on return: None Flags affected: None Example of Usage: les di, SetPtr add di, 7 ;point at 8th set in group. mov dx, seg SetPtr2 ;point at 1st set in group. lea si, SetPtr2 setdifference Discription: SetDifference computes the result of (ES:DI) := (ES:DI) - (DX:SI). The destination set is left with its original items minus those items which are also in the source set. Include: stdlib.a Routine: Nextitem ------------------ Category: Character Set Routine Registers on entry: ES:DI (contains the address of first byte of the set) Registers on return: AL (contains the first item in the set) Flags affected: None Example of Usage: les di, SetPtr add di, 7 nextitem Description: Nextitem is the routine to search the first character (item) in the set with ES:DI pointing to its mask byte. AL will return the character in the set. If the set is empty, AL will contain zero. Include: stdlib.a Routine: Rmvitem ----------------- Category: Character Set Routine Registers on entry: ES:DI (contains the address fo first byte of the set) Registers on return: AL (contains the first item in the set) Flags affected: None Example of Usage: les di, SetPtr add di, 7 rmvitem Description: Rmvitem locates the first available item in the set and removes it with ES:DI pointing to its mask byte. AL will return the item removed. If the set is empty, AL will return zero. Include: stdlib.a