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Assembly Source File | 1994-05-28 | 19.0 KB | 393 lines

;**************************************************************************** ; M A T H I O . A S M ;============================================================================ ; Functions to convert binary values to ASCII (displayable) format ; as decimal, hexadecimal or binary integers. ; Functions to convert ASCII strings, representing decimal, hexadecimal ; or binary integers, to binary values. ;--------------------------------------------------------------------------- ; Copyright (c) Simon Groes, 1994 ;--------------------------------------------------------------------------- ; Assemble with Borland Turbo Assembler v3.0 ;**************************************************************************** IDEAL DOSSEG MODEL small LOCALS ;----- Insert INCLUDE "filename" directives here INCLUDE "macro.inc" INCLUDE "common.inc" ;----- Insert EQU and = equates here hexBase = 10h binBase = 02h decBase = 0Ah DATASEG base dw 0 wordVal dw 0 ascDigit db '0123456789ABCDEF' ascBuffer db 20 DUP (0) ascBufLen = $ - ascBuffer ;----- Declare other variables with DB, DW, etc., here ;----- Specify any EXTRN variables here CODESEG ;----- Declare PUBLIC procedures here PUBLIC BinToAscii, AsciiToBin PUBLIC AsciiBinToBin, AsciiHexToBin, AsciiDecToBin ;----- Specify any EXTRN procedures here EXTRN strLength:proc, charToUpper:proc, strCopy:proc ;=============================================================== ; Procedure: =*=BinToAscii=*= ;--------------------------------------------------------------- ; Usage: Public - may be used by other asm files. ; Task: Convert 16-bit binary value to ascii format. ; Input: ax = 16-bit value ; bx = base (2,10,16) ; di = offset address of buffer to hold ascii string. ; cl = Minimum # of digits to output. ; ch = type of leading character, if cl > # digits output ; (usually '0' or SPACE). ; Output: none ; Registers: none ; Note: The buffer should be long enough to hold the ascii string ; representing the maximum value of a 1-word integer ; plus the appended 'H' plus NULL; ie 18 bytes. ;=============================================================== PROC BinToAscii SaveRegs <es,di,si,dx,cx,bx,ax> ; Save modified register(s). ;--------------------------------------------------------------- ; BinToAscii works by first dividing the original value in ax by the base. ; The remainder in dx then equals the value for the rightmost digit. ; Thereafter the quotients in ax are repeatedly divided by the base ; and the remainders in dx equal the digits from right to left. ;--------------------------------------------------------------- smove es, ds ; es -> data segment mov si, di ; si = di = calling buffer. mov di, OFFSET ascBuffer ; Address buffer. add di, ascBufLen-3 ; di -> last digit in buffer. mov [BYTE di+2], NULL ; String terminator. ;----- Valid base ? cmp bx, binBase ; Binary ? jne @@Dec ; No : Is it decimal ? mov [BYTE di+1], 'B' ; Yes: Append 'B' jmp NEAR @@Valid @@Dec: cmp bx, decBase ; Decimal ? jne @@Hex ; No : Is it hexadecimal ? mov [BYTE di+1], NULL ; Yes: Append NULL jmp NEAR @@Valid @@Hex: cmp bx, hexBase ; Hexadecimal ? jne @@Return ; No : Invalid number, end. mov [BYTE di+1], 'H' ; Yes: Append 'H'. @@Valid: mov [base], bx ; Base in 'base' variable. mov bx, OFFSET ascDigit ; Address 'ascDigit' table. std ; Auto-decrement. @@Rpt: or cl, cl ; cl = 0 ? jz @@Ra ; Yes: Don't decrement. dec cl @@Ra: cmp ax, [base] ; ax >= [base] ? jb @@Next ; No : Exit loop. xor dx, dx ; Clear dx. div [base] ; dxax/[base]; ax=quotient,dx=rest. xchg ax, dx ; ax=rest,dx=quotient. xlat ; al = ascii digit. stosb ; [es:di] = al; dec di. xchg ax, dx ; ax = quotient, dx = rest. jmp NEAR @@Rpt ; Repeat sequence. @@Next: xlat ; al = ascii digit. mov [BYTE es:di], al ; [es:di] = al. di -> string. or cl, cl ; cl = 0 ? jz @@Copy ; Yes: Copy buffer to input string. dec di ; No : di -> next char. mov al, ch ; al = '0', SPACE etc. xor ch, ch ; Now cx = cl. @@Rpt2: repnz stosb ; [es:di] = al; dec di. inc di ; di -> start of string in buffer. @@Copy: xchg di, si ; di -> call buffer; si -> string. call strCopy ; Copy to caller's buffer. @@Return: RestoreRegs <ax,bx,cx,dx,si,di,es> ret ENDP BinToAscii ;=============================================================== ; Procedure: =*=AsciiToBin=*= ;--------------------------------------------------------------- ; Usage: Public - may be used by other asm files. ; Task: Convert string of ascii numeric characters ; to 16-bit binary value. ; Input: di = offset address of ascii string. ; Note: If the string is not decimal, ; it must be terminated with the following letters: ; h or H - hexadecimal, b or B - binary. ; Output: If valid number, ax = 16-bit binary value, cf = 0. ; If invalid number, ax = 0, cf = 1. ; Registers: ax changed. ;=============================================================== PROC AsciiToBin ;----- Binary, Hexadecimal or Decimal ? call AsciiBinToBin ; Is it binary ? jnc @@Return ; Yes: cf = 0, ax = value, end. or ax, ax ; No : Not binary or invalid number? jnz @@Error ; Invalid: End with error. call AsciiHexToBin ; Is it hex ? jnc @@Return ; Yes: cf = 0, ax = value, end. or ax, ax ; No : Not hex or invalid number ? jnz @@Error ; Invalid: End with error. call AsciiDecToBin ; Is it decimal ? jnc @@Return ; Yes: cf = 0, ax = value, end. @@Error: xor ax, ax ; ax = 0. stc ; Set carry flag - error. @@Return: ret ; Return to caller. ENDP AsciiToBin ;=============================================================== ; Procedure: =*=AsciiBinToBin=*= ;--------------------------------------------------------------- ; Usage: Public - available to other asm files. ; Task: Convert ascii binary digit string to 16-bit value. ; Input: di = offset address of ascii string. ; Output: If binary, ax = 16-bit value. ; If not binary, cf = 1. ; Registers: ax is changed. ; Note: A 'B' or 'b' must be appended to all binary strings. ; If an error occurs, ax = errorcode. ; If ax = 0, a 'B' or 'b' was not appended (not binary). ; If ax = 0FFFFh, a 'B' or 'b' was appended, but ; an invalid digit (not '1' or '0') was encountered. ;=============================================================== PROC AsciiBinToBin SaveRegs <bx,cx,dx,si> ; Save modified register(s). call strLength ; cx = length of string. mov si, di ; si -> ascii string. add si, cx ; si -> NULL. dec si ; si -> 'B' or 'b'. mov al, [BYTE si] ; al = 'B' or 'b'. call charToUpper ; al = 'B'. cmp al, 'B' ; al = 'B' ? jne @@NoBin ; No : End routine 'not binary'. ;--------------------------------------------------------------- ; Binary routine reads string of '1's and '0's, starting from the ; least significant (left-most) character. If a '1' is encountered, ; the bit in dx, corresponding to the position of the '1' in the string, ; is switched on. If a '0' is encountered, it is left off. ;--------------------------------------------------------------- dec cx ; cx = # of digits. cmp cx, 16 ; Too many digits ? ja @@Inval ; End, invalid number. dec si ; si -> last digit. xor ax, ax ; Clear ax. xor dx, dx ; Clear dx. mov bx, 0001h ; Bit 0 = 1, all other bits = 0. std ; Auto-decrement. ;----- Read sequence of digits and convert to single bits. @@Rpt1: lodsb ; al = [si], si-1. sub al, '0' ; al = 0 or 1. test al, 11111110b ; If not 1 or 0, jnz @@Inval ; end routine 'invalid digit'. or al, al ; al = 0 or 1 ? jz @@Bit0 ; If 0, do nothing. or dx, bx ; If 1, insert 1 into dx. @@Bit0: shl bx, 1 ; Move to next bit. loop @@Rpt1 ; Read next digit in string. cx-1. ;----- Conversion loop complete - binary value in dx. mov ax, dx ; Value in ax. clc ; cf = 0, no error. jmp NEAR @@Return ; End routine. @@NoBin: xor ax, ax ; ax = error code for 'not binary'. jmp NEAR @@Error @@Inval: mov ax, 0FFFFh ; ax = 'invalid digit' code. @@Error: stc ; Set carry flag. @@Return: RestoreRegs <si,dx,cx,bx> ; Restore register(s). ret ; Return to caller. ENDP AsciiBinToBin ;=============================================================== ; Procedure: =*=AsciiHexToBin=*= ;--------------------------------------------------------------- ; Usage: Public - available to other asm files. ; Task: Convert ascii hexadecimal digit string to 16-bit value. ; Input: di = offset address of ascii string. ; Output: If hexadecimal, ax = 16-bit value, cf = 0. ; If not hexadecimal, cf = 1, ax = 0. ; If invalid, cf = 1, ax = 0FFFFh. ; Registers: ax is changed. ; Note: An 'H' or 'h' must be appended to all hex strings. ; If an error occurs, ax = errorcode. ; If ax = 0, a 'H' or 'h' was not appended (not hex). ; If ax = 0FFFFh, a 'H' or 'h' was appended, but ; an invalid digit (not '0' to 'F') was encountered. ;=============================================================== PROC AsciiHexToBin SaveRegs <es,bx,cx,dx,si> ; Save modified register(s). smove es, ds ; es -> data segment. mov si, di ; si -> ascii string. call strLength ; cx = length of string. add si, cx ; si -> NULL. dec si ; si -> 'H' or 'h'. std ; Auto-decrement si. lodsb ; ax = [si], si -> last digit. dec cx ; cx = # digits. call charToUpper ; al = 'H'. cmp al, 'H' ; al = 'H' ? jne @@NoHex ; No : End routine 'not hex'. ;--------------------------------------------------------------- ; The hexadecimal routine converts the character placed in al ; into a 4-bit binary value. The value is then shifted to the ; nibble (4-bit unit) corresponding to the position of the ascii ; digit in the string. This value is then 'or'd onto the dx register. ;--------------------------------------------------------------- cmp cx, 4 ; Too many digits ? ja @@Inval ; Yes: End, invalid number. xor ax, ax ; Clear ax. xor dx, dx ; Clear dl - counter. xor bx, bx ; To hold integer. std ; Auto-decrement. ; Read single digits and convert to 4-bit values. @@Rpt1: lodsb ; al = [si], si-1. cmp al, '0' ; digit >= '0' ? jb @@Inval ; No : Invalid digit, end. cmp al, '9' ; digit <= '9' ? jbe @@Sub0 ; Yes: Goto @@Sub0. call charToUpper ; Convert to uppercase. cmp al, 'A' ; digit >= 'A' ? jb @@Inval ; No : Invalid digit, end. cmp al, 'F' ; digit <= 'F' ? ja @@Inval ; No : Invalid digit, end. sub al, 'A'- ('9'+ 1) ; 'A'-('9'+1)=# chars between. @@Sub0: sub al, '0' ; Sub0: Subtract '0' from al. ; AL register now holds an increment into hex0toF table. or dl, dl ; dl = 0 ? jz @@R1a ; Yes: Don't shift ax. xchg cx, dx ; dx = cx; cx = dx. shl ax, cl ; Shift 4-bit value into position. xchg cx, dx ; Restore cx & dx. @@R1a: or bx, ax ; Insert 4-bit value into word. add dl, 4 ; dl = dl + 4. loop @@Rpt1 ; dec cx; If cx=0, exit loop. ; Conversion complete. mov ax, bx ; 16-bit value in ax. clc ; Reset (clear) carry flag. jmp NEAR @@Return ; End without error. @@NoHex: xor ax, ax ; ax = error code for 'not hex'. jmp NEAR @@Error @@Inval: mov ax, 0FFFFh ; ax = 'invalid digit' code. @@Error: stc ; Set carry flag. @@Return: RestoreRegs <si,dx,cx,bx,es> ; Restore register(s). ret ; Return to caller. ENDP AsciiHexToBin ;=============================================================== ; Procedure: =*=AsciiDecToBin=*= ;--------------------------------------------------------------- ; Usage: Public - available to other asm files. ; Task: Convert decimal digit string to 16-bit value. ; Input: di = offset address of string. ; Output: If decimal, ax = 16-bit value, cf = 0. ; If not decimal, cf = 1, ax = 0. ; If invalid digit, cf = 1, ax = 0FFFFh. ; Registers: ax is changed. ;=============================================================== PROC AsciiDecToBin SaveRegs <es,bx,cx,dx,si> ; Save modified register(s). smove es, ds ; es = data segment. mov si, di ; si -> ascii string. call strLength ; cx = length of string (# digits). add si, cx ; si -> NULL. dec si ; si -> last digit. std ; Auto-decrement si. lodsb ; al = '0'->'9', si->2nd last digit. dec cx ; cx = # digits - 1. cmp al, '0' ; al >= '0' ? jb @@NoDec ; No : Not decimal, end. cmp al, '9' ; al <= '9' ? ja @@NoDec ; No : Not decimal, end. ;----- String is decimal number. xor ah, ah ; Clear ah. xor dx, dx ; Clear dx. mov bx, 10 ; bx = 10^1. mov [wordVal], 0000h ; Clear [wordVal]. mov [base], 10 ; Base must be in word variable. sub al, '0' ; Convert to integer 0->9. or [wordVal], ax ; OR 1st (leftmost) digit onto var. @@Rpt1: jcxz @@Success ; No need for loop if only 1 digit. xor ax, ax ; Clear ax. lodsb ; al = [si], dec si. cmp al, '0' ; al >= '0' ? jb @@Inval ; No : Invalid digit, end. cmp al, '9' ; al <= '9' ? ja @@Inval ; No : Invalid digit, end. sub al, '0' ; Yes: al = 0 to 9. mul bx ; axdx = ax * bx(10^x). or dx, dx ; dx > 0 (number too large) ? jnz @@Inval ; Yes: Invalid number, end. add [wordVal], ax ; [wordVal] = [wordVal] + ax. jc @@Inval ; Number too large (invalid), end. mov ax, bx ; ax = 10^x. mul [base] ; ax = 10^(x+1). mov bx, ax ; bx = 10^(x+1). loop @@Rpt1 ; dec cx; If cx=0, exit loop. ;----- Conversion complete. @@Success: mov ax, [wordVal] ; ax = 16-bit value. clc ; Reset carry flag. jmp NEAR @@Return ; End without error. @@NoDec: xor ax, ax ; ax = error code for 'not decimal'. jmp NEAR @@Error @@Inval: mov ax, 0FFFFh ; ax = 'invalid number' code. @@Error: stc ; Set carry flag. @@Return: RestoreRegs <si,dx,cx,bx,es> ; Restore register(s). ret ; Return to caller. ENDP AsciiDecToBin END ; End of module.