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Text File | 1994-01-16 | 22.1 KB | 862 lines

***************************** DISK & FILE ******************************* ASM32 disk & file subroutines Copyright (C) 1993 Douglas Herr All rights reserved The DOS file attribute byte tells you whether a file is read-only, system, a subdirectory, or may provide other information. File attribute bits may be combined. Each bit of the file attribute means: 0 = normal files 1 = read-only 2 = hidden files 4 = system files 8 = volume label (only one per disk) 16 = subdirectories 32 = archive bit set Thus a file with an attribute of 18 is a hidden subdirectory (16 OR 2) ASM32 buffered file I/O system Several ASM32 subroutines are available for buffered file Input or Output. Files to be managed by the buffered I/O system must be opened by FOPEN or FCREATE, and must be closed by FCLOSE. Buffered file I/O will be much faster than unbuffered. ASM32's default buffer size is 4096 bytes; this can be changed by altering FBUFFER_SIZE in FOPEN.ASM and re-assembling. Up to 20 files can be managed by FOPEN; this can be changed by altering NUMBER_OF_FILES in $handle.asm and reassembling. Subroutines: FOPEN open file & initialize buffer FCREATE create file & initialize buffer FCLOSE flush & close output buffer; close file FSEEK move file pointer & update buffer FGETSTR read a string from buffer FGETCHR read a character from buffer FGET read specified number of bytes from buffer FPUTSTR write string to buffer FPUTCRLF write CR+LF to buffer FPUTCHR write character to buffer FPUT write specified number of bytes to buffer ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ DISKSIZE: determines total and free disk space Source: disksize.asm Call with: DL = drive number (drive A: = 0, default drive = -1) Returns: if CF = 0, EAX = total disk space EDX = free disk space if CF = 1, AX = DOS error code DiskSize does not trap "drive not ready" errors Uses: EAX, EDX, flags Supports: all DOS drives Example: public example_code extrn disksize:near include codeseg.inc ; code example_code proc near mov dl,0 call disksize jc disk_error ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ diskwp: determines if a floppy disk is write-protected Source: diskwp.asm Call with: DL = floppy disk number (drive A: = 0) Returns: AL = BIOS error code 0 = no error 1 = invalid disk number 3 = disk is write-protected or wrong media 128 = drive not ready Uses: EAX, flags Supports: physical drives A: and B: Example: public check_disk extrn diskwp:near include codeseg.inc ; code check_disk proc near . . . mov dl,1 ; drive B: call diskwp ; can I write to this disk? jnc short no_problem ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ DOTBAK: changes the file extension of an existing file to .BAK Source: dotbak.asm (strrchr.asm) Call with: ESI = address of a valid ASCIIZ filename in low memory dotbak deletes a previous .BAK file of this name and renames the input filename.ext to filename.bak. Returns: if CF = 0, no error if CF = 1, AL = DOS error code. If AL = 5, the previous .BAK filename is probably read-only. All other errors refer to the name change operation. Uses: AX, flags Example: extrn dotbak:near include dataseg.inc ; data disk_doc db 'DISK.DOC',0 @curseg ends include codeseg.inc ; code . . . mov esi,offset disk_doc call dotbak ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FCLOSE: close a file managed by ASM32's buffered file I/O system Source: fopen.asm ($handle.asm) Call with: BX = file handle The file must have been opened by FOPEN or FCREATE; If the file is not read-only, the output buffer will be written to the disk file before closing the file. Returns: if CF = 0, no error if CF = 1, AX = error code Uses: AX, flags Example: see FOPEN ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FCOPY: copy a file Source: fcopy.asm Call with: ESI = address of source filename EDI = address of destination filename Both filenames must be ASCIIZ strings. Drive and path need not be fully specified; filenames may not include * or ? wildcards. Returns: if CF = 0, no problem if CF = 1, AX = DOS error code Uses: EAX, CF Example: extrn fcopy:near include dataseg.inc ; data db 'b:' source db 'asm32cw.lib',0 ; copy the library to b: @curseg ends include codeseg.inc ; code . . lea esi,source mov edi,esi ; EDI also points to source sub edi,2 ; back the pointer to the 'B:' call fcopy jc oops ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FCOUNT: counts the number of files matching an ASCIIZ filespec string. The filespec string may include the '*' and '?' wildcards. Source: fcount.asm Call with: EDX pointing to filespec string CX = file attributes Returns: EAX = number of files matching the filespec string Uses: EAX Example: extrn fcount:near include dataseg.inc ; data filespec db '*.asm',0 @curseg ends include codeseg.inc ; code . . . lea edx,filespec ; address of filespec string xor cx,cx ; normal files only call fcount ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FCREATE: create new file and initialize output buffer Source: fcreate.asm ($handle.asm) Call with: EDX pointing to ASCIIZ filename The file is created with write-only access. If a file with the same name already exists, it is truncated to zero length by FCREATE. Returns: if CF = 0, AX = file handle if CF = 1, AX = error code Uses: AX, flags Example: public myprog extrn fcreate:near include dataseg.inc ; data file_name db 'ANYNEW.FIL',0 file_handle dw 0 @curseg ends include codeseg.inc ; code myprog proc near . . . lea edx,file_name call fcreate jc something_went_wrong ; go to error control code mov file_handle,ax ; save the handle . . . ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FEXIST: determines if a file exists and can be opened with read access Source: fexist.asm Call with: EDX pointing to ASCIIZ filename in low memory Returns: if CF = 0, file exists if CF = 1, AX = DOS error code Uses: AX, CF; all other flags and registers are saved Example: extrn fexist:near include dataseg.inc ; data filename db 'asm32.doc',0 @curseg ends include codeseg.inc ; code . . . lea edx,filename call fexist jnc got_the_file ; if CF = 0, go on jmp doserror ; else go to error handling code ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FFLUSH: flushes the ASM32 and DOS output buffers for specified handle Source: fflush.asm (fseek.asm) Call with: BX = file handle flushing the buffers guards against data loss in case of system failure, such as power loss Returns: if CF = 0, no error; function successful if CF = 1, AX = DOS error code Uses: AX, flags Example: include codeseg.inc extrn fflush:near ; code ; program opens file & writes to file . . . ; flush the buffers to disk mov bx,handle call fflush ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FGET: read specified number of bytes from file buffer Source: fget.asm ($handle.asm, $fget.asm) Call with: BX = file handle ECX = number of bytes requested (up to 4096 bytes) Returns: if CF = 0, EAX = number of bytes read EBX points to data in buffer if CF = 1, AX = DOS error code Uses: EAX, EBX, flags Example: extrn fopen:near, fget:near include dataseg.inc ; data file_name db 'asm32.doc',0 file_handle dw 0 @curseg ends include codeseg.inc ; code . . . lea edx,file_name call fopen jc fopen_problem mov file_handle,ax ; save for later mov bx,ax ; file handle mov ecx,8 ; I want 8 bytes call fget ; returned at [EBX] jc read_problem ; uh oh, trouble ... cmp eax,ecx ; did I get what I wanted? jne not_enough . . ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FGETCHR: read a character from a file buffer Source: fgetchr.asm ($handle.asm) Call with: BX = file handle Returns: if CF = 0, AL = next character from file buffer if CF = 1, AX = DOS error code AX = 0 if at end of file Uses: AX, flags Example: extrn fopen:near, fgetchr:near include dataseg.inc ; data file_name db 'asm32.doc',0 file_handle dw 0 @curseg ends include codeseg.inc ; code . . . lea edx,file_name call fopen jc fopen_problem mov file_handle,ax ; save for later mov bx,ax ; file handle call fgetchr ; character in AL jc read_problem . . ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FGETSTR: read an ASCII string from a file buffer Source: fgetstr.asm ($handle.asm, $fget.asm) Call with: BX = file handle ASCII strings may be terminated with either 0Dh or 0Dh+0Ah. After reading each string, FGetStr positions the buffer pointer to read the next string. String length should be less than the buffer size. See FOPEN. NOTE THAT THE STRING IN THE BUFFER IS NOT ZERO-TERMINATED. Returns: if CF = 0, EBX points to string in buffer ECX = length of ASCII string if ECX = byte length of buffer, string >= size of buffer if CF = 1, AX = DOS error code AX = 0 if end of file Uses: EBX, EAX, ECX, flags Example: extrn fopen:near, fgetstr:near include dataseg.inc ; data file_name db 'asm32.doc',0 file_handle dw 0 @curseg ends include codeseg.inc ; code . . . lea edx,file_name call fopen mov al,0 ; read-only access jc fopen_problem mov file_handle,ax ; save for later mov bx,ax ; file handle call fgetstr jc read_problem call strndup ; make a copy for later . . . ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ filelist: creates a list of file names matching a filespec mask Source: filelist.asm (fcount.asm) Call with: ESI pointing to filespec mask CX = file attribute mask Returns: if CF = 0: EDI = address of list buffer in low memory EAX = number of filenames in list ECX = list field width if CF = 1, AX = DOS error code You should use ASM32's HFREE to release the file list buffer when you're done with it. Uses: EAX, ECX, EDI, flags Example: public myproc extrn filelist:near include dataseg.inc ; data filespec db '*.*',0 @curseg ends include codeseg.inc ; code . . . lea esi,filespec mov cx,16 ; normal files and subdirectories call filelist jc cant_do_it ; oops ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FOPEN: opens existing file and initializes ASM32 buffered I/O Source: fopen.asm ($handle.asm) Call with: EDX pointing to name of file to be opened AL = access mode 0 = read-only access 1 = write-only access 2 = read-write access NOT SUPPORTED YET Returns: if CF = 0, AX = file handle if CF = 1, AX = ASM32 or DOS error code; file not opened if AX = 0, insufficient memory available if AX = 0FFFFh, no handles available in ASM32 I/O array; change NUMBER_OF_HANDLES in $handle.asm and re-assemble (default = 20 handles) Uses: AX, flags Example: public myprog extrn fopen:near, fclose:near include dataseg.inc ; data file_name db 'ASM32.DOC',0 file_handle dw 0 @curseg ends include codeseg.inc ; code myprog proc near . . . lea edx,file_name xor al,al ; read-only access call fopen jc something_went_wrong mov file_handle,ax ; save the handle . . . ; all done with this file mov bx,file_handle call fclose ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FPUT: write specified number of bytes to output file buffer Source: fput.asm ($handle.asm) Call with: BX = file handle EDI pointing to data to write ECX = number of bytes to write Returns: if CF = 0, no error if CF = 1, AX = error code Uses: EAX, flags Example: public myproc extrn fput:near extrn fputchr:near extrn fputcrlf:near include dataseg.inc ; data data1 db 'several bytes may be written at once' data_len equ $-data1 @curseg ends include codeseg.inc ; code . . . mov bx,output_handle lea edi,data1 ; EDI -> data1 mov ecx,data_len ; bytes to write call fput call fputcrlf ; write CR+LF for new line ; in ASCII text file mov al,26 ; End-of-File byte (optional) call fputchr ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FPUTCHR: write one character to output file buffer Source: fputchr.asm (fput.asm) Call with: BX = output file handle AL = character to write Returns: if CF = 1, AX = DOS error code if CF = 0, no error Uses: AX, flags Example: see FPUT ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FPUTCRLF: write CR+LF pair to output file buffer Source: fputcrlf.asm (fput.asm) Call with: BX = output file handle; file must have been opened by FOPEN or FCREATE Returns: if CF = 0, no error if CF = 1, AX = DOS error code Uses: AX, flags Example: see FPUT ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FPUTSTR: write an ASCIIZ string to output buffer Source: fputstr.asm (strlen.asm, fput.asm) Call with: BX = file handle EDI pointing to ASCIIZ string Returns: if CF = 0, EAX = bytes written if CF = 1, AX = DOS error code Uses: EAX, flags Example: public myproc extrn fputstr:near extrn fputcrlf:near include dataseg.inc ; data strptr dd 0 ; pointer to string, assigned by program @curseg ends include codeseg.inc ; code . . . mov bx,output_handle mov edi,strptr ; EDI -> string call fputstr call fputcrlf ; write CR+LF for new line ; in ASCII text file ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FSEEK: move file pointer for a file opened by FOPEN Source: fseek.asm ($handle.asm) Call with: BX = file handle AL = method code: 0 = absolute offset from start of file 1 = signed offset from current file pointer 2 = signed offset from end of file EDX = dword offset Returns: if CF = 1, AX = DOS error code if CF = 0, EAX = new location of file pointer Uses: EAX, flags Example: public whoknows extrn fopen:near, fseek:near include dataseg.inc ; data file0 db 'file0.dat',0 @curseg ends include codeseg.inc ; code whoknows proc near . . . mov edx,offset file0 mov al,1 ; write only call fopen jc error xor edx,edx ; zero offset mov al,2 ; relative to end of file call fseek ; move pointer to end of file ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ FSIZE: determines a file's size Source: fsize.asm Call with: BX = valid file handle Returns: if CF = 0, EAX = file size if CF = 1, AX = DOS error code Uses: EAX, CF Example: extrn fsize:near include dataseg.inc ; data filenam db 'ASM32.DOC',0 ; ASCIIZ filename @curseg ends include codeseg.inc ; code . . . lea edx,filenam ; point to filename in low memory mov al,0 ; read-only access (not required by FSIZE) call fopen ; open the file jc oops ; jump to error control ; else no problem - continue mov bx,ax ; file handle in BX call fsize ; returns file size in EAX ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ MLOAD: read a file into far memory, allocating new selector Source: mload.asm (fsize.asm) Call with: [EDX] pointing to ASCIIZ filename Returns: if CF = 0, BX = selector of memory block EAX = bytes loaded from disk if CF = 1, AX = DOS error code Uses: EAX, BX, CF Example: include model.inc public test_mload extrn mload:near include dataseg.inc filesel dw 0 fname db 'filename.txt',0 file_size dd 0 include codeseg.inc test_mload proc near . . lea edx,fname call mload ; read file into DOS memory jc short no_good ; jump if there was a problem mov filesel,bx ; save new selector of memory block mov file_size,eax ; save file size no_good: ; return with CF = 1 if error ret ; CF = 0 if no error test_mload endp end ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ MSAVE: write memory block to file Source: msave.asm Call with: [EDX] pointing to ASCIIZ filename ES:[EBX] -> first byte to write EAX = number of bytes to write Returns: if CF = 0, no error if CF = 1, AX = DOS error code Uses: EAX, flags Example: include model.inc public test_msave extrn msave:near include dataseg.inc filesel dw 0 fname db 'filename.txt',0 file_size dd 0 include codeseg.inc test_msave proc near . . lea edx,fname mov eax,file_size mov es,filesel ; selector of memory block xor ebx,ebx ; start at beginning of memory block call mload ; read file into DOS memory ; return with CF = 1 if error ret ; CF = 0 if no error test_msave endp end ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ QFNAME: qualifies a filename Source: qfname.asm Call with: EBX pointing to a filename; the filename may contain drive specification and/or complete or partial path name. Drive specification and path name not required. Returns: ESI pointing to the full DRIVESPEC:\PATH\FILENAME ECX = length of full filename Note that ESI points to QFName's buffer space; the next call to QFName will return a new filename at the same address. Uses: ESI, ECX, flags Example: include dataseg.inc ; data docs db '*.doc',0 ; search for .DOC files in current directory @curseg ends include codeseg.inc ; code . . . lea ebx,docs call qfname ; returns 'drive:\path\*.doc'