compare.asm

想学习汇编语言的

TITLE Comparing Strings                    (Compare.asm)

; Last update: 9/7/01

INCLUDE Irvine32.inc

Str_compare PROTO,
	string1:PTR BYTE,
	string2:PTR BYTE

.data
string_1 BYTE "ABCDEFG",0
string_2 BYTE "ABCDEFG",0
string_3 BYTE 0
string_4 BYTE 0

.code
main PROC
	call Clrscr

	INVOKE Str_compare,
	  ADDR string_4,
	  ADDR string_3
	Call DumpRegs

	exit
main ENDP

;-----------------------------------------------------
Str_compare PROC USES eax edx esi edi,
	string1:PTR BYTE,
	string2:PTR BYTE
;
; Compare two strings.
; Returns nothing, but the Zero and Carry flags are affected
; exactly as they would be by the CMP instruction.
;-----------------------------------------------------
    mov esi,string1
    mov edi,string2

L1: mov  al,[esi]
    mov  dl,[edi]
    cmp  al,0    			; end of string1?
    jne  L2      			; no
    cmp  dl,0    			; yes: end of string2?
    jne  L2      			; no
    jmp  L3      			; yes, exit with ZF = 1

L2: inc  esi      			; point to next
    inc  edi
    cmp  al,dl   			; chars equal?
    je   L1      			; yes: continue loop
                 			; no: exit with flags set
L3: ret
Str_compare ENDP

END main