String Instructions
Name Description Code Operation operands operand size
movs Move string movs dest = source    
movsb
movsw
movsd		    
movs byte dest,source
movs word dest,source
movs dword dest,source		 [es:di],[s_reg:si]
[es:edi],[s_reg:esi]		 byte
word
dword
cmps Compare string cmps

dest - source,
ZF=1 if equal,
ZF=0 if not equal

(updat A,S,P,C,O)

   
cmpsb
cmpsw
cmpsd		    
cmps byte source,dest
cmps word source,dest
cmps dword source,dest		 [s_reg:si],[es:di]
[s_reg:esi],[es:edi]		 byte
word
dword
scas Scan string scas

dest - al/ax/eax,
ZF=1 if equal,
ZF=0 if not equal

(updat A,S,P,C,O)

    
scasb
scasw
scasd		    
scas byte dest
scas word dest
scas dword dest		 [di]
[edi]
[es:di]
[es:edi]		 byte
word
dword
lods Load string lods al/ax/eax = source    
lodsb
lodsw
lodsd		    
lods byte source
lods word source
lods dword source		 [s_reg:si]
[s_reg:esi]		 byte
word
dword
stos Store string stos dest = al/ax/eax    
stosb
stosw
stosd		    
stos byte dest
stos word dest
stos dword dest		 [di]
[edi]
[es:di]
[es:edi]		 byte
word
dword
ins Input string from port ins port -> dest    
insb
insw
insd		    
ins byte dest,port
ins word dest,port
ins dword dest,port		 [di],dx
[edi],dx		  
outs Output string to port outs source -> port    
outsb
outsw
outsd		    
outs port,byte source
outs port,word source
outs port,dword source		 dx,[si]
dx,[esi]
dx,[s_reg:si]
dx,[s_reg:esi]		  
rep Repeat while ECX not zero rep <string operation> dec cx/ecx,
repeat until cx/ecx=0 		   
repe
repz		 Repeat while equal
Repeat while zero		 repz <string operation>
repe <string operation>		 dec cx/ecx,
repeat until cx/ecx=0 or ZF=0		    
repne
repnz		 Repeat while not equal
Repeat while not zero		 repnz <string operation>
repne <string operation>		 dec cx/ecx,
repeat until cx/ecx=0 or ZF=1