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Volume 4: Base IA-32 Instruction Reference
4:337
REP/REPE/REPZ/REPNE
/REPNZ—Repeat String Operation Prefix
Description
Repeats a string instruction the number of times specified in the count register (ECX) or
until the indicated condition of the ZF flag is no longer met. The REP (repeat), REPE
(repeat while equal), REPNE (repeat while not equal), REPZ (repeat while zero), and
REPNZ (repeat while not zero) mnemonics are prefixes that can be added to one of the
string instructions. The REP prefix can be added to the INS, OUTS, MOVS, LODS, and
STOS instructions, and the REPE, REPNE, REPZ, and REPNZ prefixes can be added to
the CMPS and SCAS instructions. (The REPZ and REPNZ prefixes are synonymous forms
of the REPE and REPNE prefixes, respectively.) The behavior of the REP prefix is
undefined when used with non-string instructions.
The REP prefixes apply only to one string instruction at a time. To repeat a block of
instructions, use the LOOP instruction or another looping construct.
F3 6C
REP INS
r/m8
, DX
Input ECX bytes from port DX into ES:[EDI]
F3 6D
REP INS
r/m16
,DX
Input ECX words from port DX into ES:[EDI]
F3 6D
REP INS
r/m32
,DX
Input ECX doublewords from port DX into ES:[EDI]
F3 A4
REP MOVS
m8,m8
Move ECX bytes from DS:[ESI] to ES:[EDI]
F3 A5
REP MOVS
m16,m16
Move ECX words from DS:[ESI] to ES:[EDI]
F3 A5
REP MOVS
m32,m32
Move ECX doublewords from DS:[ESI] to ES:[EDI]
F3 6E
REP OUTS DX,
r/m8
Output ECX bytes from DS:[ESI] to port DX
F3 6F
REP OUTS DX,
r/m16
Output ECX words from DS:[ESI] to port DX
F3 6F
REP OUTS DX,
r/m32
Output ECX doublewords from DS:[ESI] to port DX
F3 AC
REP LODS AL
Load ECX bytes from DS:[ESI] to AL
F3 AD
REP LODS AX
Load ECX words from DS:[ESI] to AX
F3 AD
REP LODS EAX
Load ECX doublewords from DS:[ESI] to EAX
F3 AA
REP STOS
m8
Fill ECX bytes at ES:[EDI] with AL
F3 AB
REP STOS
m16
Fill ECX words at ES:[EDI] with AX
F3 AB
REP STOS
m32
Fill ECX doublewords at ES:[EDI] with EAX
F3 A6
REPE CMPS
m8,m8
Find nonmatching bytes in ES:[EDI] and DS:[ESI]
F3 A7
REPE CMPS
m16,m16
Find nonmatching words in ES:[EDI] and DS:[ESI]
F3 A7
REPE CMPS
m32,m32
Find nonmatching doublewords in ES:[EDI] and DS:[ESI]
F3 AE
REPE SCAS
m8
Find non-AL byte starting at ES:[EDI]
F3 AF
REPE SCAS
m16
Find non-AX word starting at ES:[EDI]
F3 AF
REPE SCAS
m32
Find non-EAX doubleword starting at ES:[EDI]
F2 A6
REPNE CMPS
m8,m8
Find matching bytes in ES:[EDI] and DS:[ESI]
F2 A7
REPNE CMPS
m16,m16
Find matching words in ES:[EDI] and DS:[ESI]
F2 A7
REPNE CMPS
m32,m32
Find matching doublewords in ES:[EDI] and DS:[ESI]
F2 AE
REPNE SCAS
m8
Find AL, starting at ES:[EDI]
F2 AF
REPNE SCAS
m16
Find AX, starting at ES:[EDI]
F2 AF
REPNE SCAS
m32
Find EAX, starting at ES:[EDI]
Summary of Contents for ITANIUM ARCHITECTURE
Page 1: ......
Page 7: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 199: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 352: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 589: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 590: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 591: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 603: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...
Page 604: ......