memicmp_asm

June 5, 2009 Code by sealplusplus

From Microsoft Visual Studio 9.0 

向微软学习，到代码中去，广阔天地大有作为

 

 

 

Matrix is everywhrer so you can load it, and creat it.

 

 

        page        ,132

        title        memicmp - compare blocks of memory, ignore case

 

;memicmp.asm - compare memory, ignore case

;

 

 

        .xlist

        include cruntime.inc

        .list

page

 

;

;********************************************************************

        CODESEG

        public  __ascii_memicmp

__ascii_memicmp proc /

        uses edi esi ebx, /

        first:ptr byte, /

        last:ptr byte, /

        count:IWORD

        mov     ecx,[count]     ; cx = count

        or      ecx,ecx

        jz      short toend     ; if count=0, nothing to do

        mov     esi,[first]     ; si = first

        mov     edi,[last]      ; di = last

        ; C locale

        mov     bh,'A'

        mov     bl,'Z'

        mov     dh,'a'-'A'      ; add to cap to make lower

        align   4

lupe:

        mov     ah,[esi]        ; ah = *first

        add     esi,1           ; first++

        mov     al,[edi]        ; al = *last

        add     edi,1           ; last++

        cmp     ah,al         ; test for equality BEFORE onverting case

        je      short dolupe

        cmp     ah,bh           ; ah < 'A' ??

        jb      short skip1

        cmp     ah,bl           ; ah > 'Z' ??

        ja      short skip1

        add     ah,dh           ; make lower case

skip1:

        cmp     al,bh           ; al < 'A' ??

        jb      short skip2

        cmp     al,bl           ; al > 'Z' ??

        ja      short skip2

        add     al,dh           ; make lower case

skip2:

        cmp     ah,al           ; *first == *last ??

        jne     short differ    ; nope, found mismatched chars

dolupe:

        sub     ecx,1

        jnz     short lupe

        jmp     short toend     ; cx = 0, return 0

differ:

        mov     ecx,-1          ; assume last is bigger

                                ; *** can't use "or ecx,-1" due to flags ***

        jb      short toend     ; last is, in fact, bigger (return -1)

        neg     ecx             ; first is bigger (return 1)

toend:

        mov     eax,ecx         ; move return value to ax

        ret                     ; _cdecl return

__ascii_memicmp endp

        end