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PsL Monthly 1993 December
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PSL Monthly Shareware CD-ROM (December 1993).iso
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prgmming
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stdlib1.exe
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PRINTF.ASM
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Assembly Source File
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1990-06-23
|
15KB
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707 lines
stdlib segment para public 'slcode'
assume cs:stdlib
extrn sl_Putc:far, sl_Puti:far, sl_ISize:far
extrn sl_Putw:far, sl_Puth:far
extrn sl_Putu:far, sl_PutUL:far, sl_ULSize:far
extrn sl_LSize:far, sl_USize:far, sl_PutL:far
;
putc equ sl_putc
puti equ sl_puti
ISize equ sl_ISize
putw equ sl_putw
puth equ sl_puth
putu equ sl_putu
putul equ sl_putul
ulsize equ sl_ulsize
lsize equ sl_lsize
usize equ sl_usize
putl equ sl_putl
;
;
; Printf- Like the "C" routine by the same name. Calling sequence:
;
; call printf
; db "format string",0
; dd item1, item2, ..., itemn
;
; The format string is identical to "C". Item1..Itemn are pointers to
; values to print for this string. Each item must be matched by the
; corresponding "%xxx" item in the format string.
;
; Format string format:
;
; 1) All characters, except the following, are printed to the standard
; output as-is.
;
; 2) "\" is the escape character. Anything following it is printed
; as-is except standard "C" values like \r, \n, \b, \t, etc. If
; a decimal digit follows the back-slash, printf assumes that this
; is a hexadecimal number and converts following three digits to
; an ASCII character and prints it. Other back-slash operators are
; just like those for "C".
;
; 3) Format Control Strings:
;
; General format: "%s\cn^f" where:
; s = -
; n = a decimal integer
; c = a fill character
; ^ = ^
; f = a format character
;
; All fields except "%" and "f" are optional.
;
; s = - Left justify value and use fill character.
; \c present Use "c" as fill character.
; n present Use "n" as the minimum field width.
; ^ present The address associated with f is the address of a
; pointer to the object, not the address of
; the object itself. The pointer is a far ptr.
;
; f is one of the following
;
; d - Print signed integer in decimal notation.
; i - Print signed integer in decimal notation.
; x - Print word value in hexadecimal notation.
; h - Print byte value in hexadecimal notation.
; u - Print unsigned integer in decimal notation.
; c - Print character.
; s - Print string.
;
; ld- Print long signed integer.
; li- Print long unsigned integer.
; lx- Print long hexadecimal number.
; lu- Print long unsigned number.
;
;
; Calling Sequence:
;
; call Printf
; db "Format String",0
; dd adrs1, adrs2, ..., adrsn
;
; Where the format string is ala "C" (and the descriptions above)
; and adrs1..adrsn are addresses (far ptr) to the items to print.
; Unless the "^" modifier is present, these addresses are the actual
; addresses of the objects to print.
;
;
;
cr equ 0dh
ff equ 0ch
lf equ 0ah
tab equ 09h
bs equ 08h
;
RtnAdrs equ 2[bp]
;
public sl_printf
sl_printf proc far
push bp
mov bp, sp
pushf
push ax
push bx
push cx
push dx
push di
push si
push es
push ds
;
; Get pointers to the return address (format string).
cld
les di, RtnAdrs
lds si, RtnAdrs
;
; Okay, search for the end of the format string. After these instructions,
; di points just beyond the zero byte at the end of the format string. This,
; of course, points at the first address beyond the format string.
;
mov al, 0
mov cx, 65535
repne scasb
;
PrintItems: lodsb ;Get char si points at.
cmp al, 0 ;EOS?
jz PrintfDone
cmp al, "%" ;Start of a format string?
jz FmtItem
cmp al, "\" ;Escape character?
jnz PrintIt
call GetEscChar
PrintIt: call Putc
jmp PrintItems
;
FmtItem: call GetFmtItem ;Process the format item here.
jmp PrintItems
;
PrintfDone: mov RtnAdrs, di ;Put out new return address.
pop ds
pop es
pop si
pop di
pop dx
pop cx
pop bx
pop ax
pop bp
popf
ret
sl_printf endp
;
; GetEscChar- Handles items immediately following the escape character "\".
;
; Special escape characters (upper/lower case is acceptable):
;
; n Newline (cr/lf)
; t tab
; b backspace
; r return
; l line feed
; f formfeed
; \ \
; % &
; 0xhh Char with hex character code hh. Must have exactly
; two hexadecimal digits.
;
GetEscChar proc near
lodsb ;Get next character
cmp al, 'n'
je RtnNL
cmp al, 'N'
je RtnNL
cmp al, 't'
je RtnTab
cmp al, 'T'
je RtnTab
cmp al, 'b'
je RtnBS
cmp al, 'B'
je RtnBS
cmp al, 'r'
je RtnRtn
cmp al, 'R'
je RtnRtn
cmp al, 'l'
je RtnLF
cmp al, 'L'
je RtnLF
cmp al, 'f'
je RtnFF
cmp al, 'F'
je RtnFF
;
; Check for the presence of a 0xhh value here:
;
cmp al, '0'
jne RtnChar
cmp byte ptr [si], 'x'
je GetHex
cmp byte ptr [si], 'X'
jne RtnChar
;
; Okay, process the hex value here. Note that exactly two hex digits must
; follow the 0x.
;
GetHex: inc si ;Point at first hex digit.
lodsb ;Get first hex digit.
and al, 05fh ;l.c. -> u.c.
cmp al, 'A'
jb GotIt
sub al, '7'
GotIt: shl al, 1 ;Put into H.O. nibble.
shl al, 1
shl al, 1
shl al, 1
mov ah, al ;Save for later
lodsb ;Get next char.
and al, 05fh
cmp al, 'A'
jb GotIt2
sub al, '7'
GotIt2: and al, 0fh
or al, ah
ret ;Return hex constant.
;
; RtnNL (return Newline) cheats. It needs to return two characters.
; Since GetEscChar only returns a single character, this code goes ahead
; and calls putc to output the CR and the returns the LF.
;
RtnNL: mov al, cr
call Putc
mov al, lf
ret
;
RtnTab: mov al, tab
ret
;
RtnBS: mov al, bs
ret
;
RtnRtn: mov al, cr
ret
;
RtnLF: mov al, lf
ret
;
RtnFF: mov al, ff
RtnChar: ret
;
GetEscChar endp
;
;
;
GetFmtItem proc near
lodsb ;Get char beyond "%"
;
mov cx, 1 ;Default field width is 1.
mov dl, 0 ;Default is right justified
mov dh, ' ' ;Default fill char is space.
mov ah, ' ' ;Assume straight ptr, not handle.
;
; See if the user wants the value left justified:
;
cmp al, '-'
jne NotLeftJust
inc dl ;Set to right justified
lodsb ;Get next character.
;
; See if the user wants to change the padding character.
;
NotLeftJust: cmp al, '\'
jne NoPadChange
lodsb ;Get Padding Character.
mov dh, al ;Save padding character.
lodsb ;Get next character
;
; See if the user wants a different field width:
;
NoPadChange: cmp al, '0'
jb NoFldWidth
cmp al, '9'
ja NoFldWidth
call GetDecVal
;
; See if the user wants to specify a handle rather than a straight pointer
;
NoFldWidth: cmp al, '^'
jne ChkFmtChars
mov ah, al
lodsb ;Skip "^" character
;
; Okay, process the format characters down here.
;
ChkFmtChars: and al, 05fh ;l.c. -> U.C.
cmp al, 'D'
je PrintDec
cmp al, 'I'
je PrintDec
cmp al, 'C'
je PrintChar
;
cmp al, 'X'
jne TryH
jmp PrintHexWord
;
TryH: cmp al, 'H'
jne TryU
jmp PrintHexByte
;
TryU: cmp al, 'U'
jne TryString
jmp PrintUDec
;
TryString: cmp al, 'S'
jne TryLong
jmp PrintString
;
TryLong: cmp al, 'L'
jne Default
;
; If we've got the "L" modifier, this is a long value to print, get the
; data type character as the next value:
;
lodsb
and al, 05fh ;l.c. -> U.C.
cmp al, 'D'
je JmpDec
cmp al, 'I'
jne TryLU
JmpDec: jmp LongDec
;
TryLU: cmp al, 'U'
jne TryX
jmp LongU
;
TryX: cmp al, 'X'
jne Default
jmp LongX
;
;
;
; If none of the above, simply return without printing anything.
;
Default: ret
;
;
;
;
;
; Print a signed decimal value here.
;
PrintDec: call GetPtr ;Get next pointer into ES:BX
mov ax, es:[bx] ;Get value to print.
call ISize ;Get the size of this guy.
sub cx, ax ;Compute padding
mov ax, es:[bx] ;Retrieve value to print.
js NoPadDec ;Is CX negative?
cmp dl, 0 ;Right justified?
jne LeftJustDec
call PrintPad ;Print padding characters
call Puti ;Print the integer
ret ;We're done!
;
; Print left justified value here.
;
LeftJustDec: call Puti
call PrintPad
ret
;
; Print non-justi