Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1639

REP/REPE/REPZ/REPNE /REPNZ—Repeat String Operation Prefix
F3 6C
F3 6D
F3 6D
F3 A4
F3 A5
F3 A5
F3 6E
F3 6F
F3 6F
F3 AC
F3 AD
F3 AD
F3 AA
F3 AB
F3 AB
F3 A6
F3 A7
F3 A7
F3 AE
F3 AF
F3 AF
F2 A6
F2 A7
F2 A7
F2 AE
F2 AF
F2 AF
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.
Volume 4: Base IA-32 Instruction Reference
REP INS r/m8 , DX
REP INS r/m16 ,DX
REP INS r/m32 ,DX
REP MOVS m8,m8
REP MOVS m16,m16
REP MOVS m32,m32
REP OUTS DX, r/m8
REP OUTS DX, r/m16
REP OUTS DX, r/m32
REP LODS AL
REP LODS AX
REP LODS EAX
REP STOS m8
REP STOS m16
REP STOS m32
REPE CMPS m8,m8
REPE CMPS m16,m16
REPE CMPS m32,m32
REPE SCAS m8
REPE SCAS m16
REPE SCAS m32
REPNE CMPS m8,m8
REPNE CMPS m16,m16
REPNE CMPS m32,m32
REPNE SCAS m8
REPNE SCAS m16
REPNE SCAS m32
Input ECX bytes from port DX into ES:[EDI]
Input ECX words from port DX into ES:[EDI]
Input ECX doublewords from port DX into ES:[EDI]
Move ECX bytes from DS:[ESI] to ES:[EDI]
Move ECX words from DS:[ESI] to ES:[EDI]
Move ECX doublewords from DS:[ESI] to ES:[EDI]
Output ECX bytes from DS:[ESI] to port DX
Output ECX words from DS:[ESI] to port DX
Output ECX doublewords from DS:[ESI] to port DX
Load ECX bytes from DS:[ESI] to AL
Load ECX words from DS:[ESI] to AX
Load ECX doublewords from DS:[ESI] to EAX
Fill ECX bytes at ES:[EDI] with AL
Fill ECX words at ES:[EDI] with AX
Fill ECX doublewords at ES:[EDI] with EAX
Find nonmatching bytes in ES:[EDI] and DS:[ESI]
Find nonmatching words in ES:[EDI] and DS:[ESI]
Find nonmatching doublewords in ES:[EDI] and DS:[ESI]
Find non-AL byte starting at ES:[EDI]
Find non-AX word starting at ES:[EDI]
Find non-EAX doubleword starting at ES:[EDI]
Find matching bytes in ES:[EDI] and DS:[ESI]
Find matching words in ES:[EDI] and DS:[ESI]
Find matching doublewords in ES:[EDI] and DS:[ESI]
Find AL, starting at ES:[EDI]
Find AX, starting at ES:[EDI]
Find EAX, starting at ES:[EDI]
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