汇编-CBW将有符号数字节转换为字

将AL寄存器中的有符号数扩展为AX中的有符号数。如果AL是正数，则AH会被设置为0；如果AL是负数，则AH会被设置为FFH

.386  
.model flat,stdcall 
option casemap:none
.stack 4096

Include Irvine32.inc
includelib Irvine32.lib

ExitProcess PROTO,dwExitCode:DWORD  
 
.data   
packed_1 WORD 4536h 
packed_2 WORD 7207h 
sum DWORD ?

 
.code   
main PROC   
    
    
    mov al,5h  ;ah=xxh   al=05h
    cbw        ;ax=0005h
    
    mov al,-90   ;al=A6h
    cbw         ;ax=FFFA6



    INVOKE ExitProcess,0  
main ENDP   
END main