ASM 函數調用過程

MyData segment

MyData ends

MyCode segment
MyAdd proc
wArg2 = WORD ptr 8
wArg1 = WORD ptr 6
@wTest1 = WORD ptr -2
@wTest2 = WORD ptr -4
push bp;上一個函數的棧頂壓棧
mov bp, sp;儲存剛進入函數時，棧頂指標

sub sp, 4
push cx; cx, bx兩個數壓棧的作用是？儲存寄存器環境嗎
push bx

mov [bp + @wTest1], 6
mov [bp + @wTest2], 8

; L1 * arg1 + L2 * arg2
mov ax, [bp + wArg2]; [bp+wArg2]是cx,8
mul [bp + @wTest2] ; 結果是dx. ax，[bp+@wTest2]是
mov bx, ax
mov cx, dx

mov ax, [bp + wArg1]
mul [bp + @wTest1]

add ax, bx
adc dx, cx

pop bx ;
pop cx
mov sp, bp ;準備退出函數了，還原棧頂 為ret4做準備
pop bp ;
ret 4 ; pop ip / pop cs / add sp, 4 (__stdcall約定)
MyAdd endp
START:
mov ax, MyData
mov ds, ax
;MyAdd(0x32, 0x12);
mov ax, 12h
push ax
mov ax, 32h
push ax
call MyAdd

mov ax, 4c00h
int 21h
MyCode ends
end START