Category : Utilities for DOS and Windows Machines
Archive   : DUMP.ZIP
Filename : STRFILL.S

TITLE strfill: Fill a string with a single character for 8088/86.
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; pid=strfill version = 1.1 November 4, 1985
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; language: Xenix 8088/8086 assembly (DOS cross development system)
; sccs keywords - - @(#)8088/8086 C subroutine strfl86.s 1.1@(#)
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; change history
; 04 November 1985 - Initial release of strfill for 8088/8086 machines
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; strfill version 1.1; Copyright (c) 1985, by Eric Erickson
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;
; strfl86: fill a string for a specified length with a single padding character
;
; syntax:
; strfill(string, length, pad);
;
; char *string;
; int length;
; char pad;
;
; Memory Model: small, medium
;
; Stack offsets for parameters
;
; string=4 address of string
; length=6 length of string to fill
; pad=8 padding character to fill with
;
; Register usage
; bp: pointer to current top of stack (standard C linkage)
; sp: stack pointer
; al: byte character to fill string with
; si: counter for number of bytes filled
; di: number of bytes to fill in string
; bx: address of byte being filled
;
;
ASSUME CS:_TEXT
PUBLIC _strfill
_TEXT SEGMENT WORD PUBLIC 'CODE'
PUBLIC _strfill
_strfill PROC NEAR
push bp ; save current bp register
mov bp,sp ; set new bp register for stack access
push di ; save register about to be trashed
push si ; ditto for this one
push bx ; and this one also
;
; Do all variable initialization
;
mov si,1 ; initialize bytes filled counter
;
; Get all the initial values needed to do the work. The values retrieved are:
; length to fill
; character to fill with
; starting address of string to fill
;
mov di,[bp+6] ; get the length to fill
mov al,[bp+8] ; get the fill character
mov bx,[bp+4] ; get the starting address of the string
jmp check_limit ; check for zero length fill (why anyone would
; do this I don't know but lets check it anyway)
fill_loop:
mov [bx],al ; insert the fill character
inc si ; increment the count of bytes filled
inc bx ; increment the target pointer
check_limit:
cmp si,di ; check to see if we are done filling
jl fill_loop ; sorry, we're not; go back and continue
;
; All done filling string. Set EOS marker and leave
;
mov BYTE PTR [bx],0 ; set the end of string marker
xor ax,ax ; zero out return code parameter
pop bx ; restore all
pop si ; the registers
pop di ; we trashed doing work
mov sp,bp ; restore the stack pointer
pop bp ; get bp back also
ret
_strfill ENDP

_TEXT ENDS
END