STD set Director 将DF=1
MOVSB ES:[DI]=DS:[SI]
MUL IMUL
MUL SRC 无符号 IMUL SRC 有符号
MUL/IMUL reg/mem8 -> AX<-AL*reg/mem8
MUL/IMUL reg/mem16 -> DX:AX<-AX*reg/mem16
MUL/IMUL reg/mem32 -> EDX:EAX<-EAX*reg/mem32
IMUL: 改变CF，OF；CF=OF=1，高位不为0；CF=OF=0，高位为0，无符号数/有符号数没有进位
IMUL REG,SRC,IMM; REG<-REG*sign-extened IMM
16/32,16/32,8 ; 16,16,16(->extened) ; 32,32,16(->extened)
DIV IDIV
DIV SRC;无符号 IDIV SRC ;有符号
DIV/IDIV reg/mem8 ;AX/reg/mem8,余数->AH,商->AL
DIV/IDIV reg/mem16; DX:AX/reg/mem16,余数->DX，商->AX
DIV/IDIV reg/mem32; EDX:EAX/reg/mem32,余数->EDX,商->EAX
expend 被除数
CBW：AL->AX
CWD:AX->DX:AX
CWDE:AX->EAX
CDQ:EAX->EDX:EAX
e,g,1
<c>unsigned A=1020,B=1000;unsigned N1,N2;N1=A/B,N2=A%B
<a>
A WORD 1020
B WORD 1000
N1 WORD ?
N2 WORD ?
MOV AX A
MOV DX,0;将DX初始化为0
CWD
IDIV B
MOV N1,AX
MOV N2,DX
e.g.2
suppose X,Y,Z,V are 16-bit signed number,calculate (V-(X*Y+Z))/X.quotient in AX,remainder in DX
MOV AX,X
IMUL Y
MOV BX,AX
MOV CX,DX
MOV AX,Z
CWD
ADD BX,AX
ADC CX,DX
MOV AX,V
CWD
SUB AX,BX
SBB DX,CX
IDIV X
AAA
将2个unpacked BCD码的和生成一个unpacked BCD码
MOV AL,09H
MOV BL,04H
ADD AL,BL
AAA
改变AF：低8位向高8位进位，AF=1；AH<-(AH)+1
AAS
MOV AL,0106H
MOV BL,7H
SUB AL,BL
AAS
改变AF：低8位襄高8位借位，AF=1；AH<-(AH)-1
AAM
MOV AL,09H
MOV BL,07H
MUL BL
AAM
AAD
MOV AX,0208H
MOV BL,04H
AAD;AL<-(AL)+(AH)*10
DIV AX,BL
DAA
MOV AL,54H
MOV BL,43H
ADD AL,BL
DAA
DAS
A=4612;B=3576
MOV AL,A
SUB AL,B
DAS
MOV B,AL
MOV AL,A+1
SBB AL,B+1
DAS
MOV B+1,AL