String Instructions (x86 Assembly Language Reference Manual)

x86 Assembly Language Reference Manual

String Instructions

The string instructions operate on strings of bytes. Operations include storing strings in memory, loading strings from memory, comparing strings, and scanning strings for substrings.

Note –

The Solaris mnemonics for certain instructions differ slightly from the Intel/AMD mnemonics. Alphabetization of the table below is by the Solaris mnemonic. All string operations default to long (doubleword).

Table 3–8 String Instructions


Solaris Mnemonic	Intel/AMD Mnemonic	Description	Notes
`cmps{q}`	`CMPS`	compare string	`cmpsq` valid only under `-xarch=amd64`
`cmpsb`	`CMPSB`	compare byte string
`cmpsl`	`CMPSD`	compare doubleword string
`cmpsw`	`CMPSW`	compare word string
`lods{q}`	`LODS`	load string	`lodsq` valid only under `-xarch=amd64`
`lodsb`	`LODSB`	load byte string
`lodsl`	`LODSD`	load doubleword string
`lodsw`	`LODSW`	load word string
`movs{q}`	`MOVS`	move string	`movsq` valid only under `-xarch=amd64`
`movsb`	`MOVSB`	move byte string	`movsb` is not `movsb{wlq}`. See Table 3–1
`movsl`, `smovl`	`MOVSD`	move doubleword string
`movsw`, `smovw`	`MOVSW`	move word string	`movsw` is not `movsw{lq}`. See Table 3–1
`rep`	`REP`	repeat while `%ecx` not zero
`repnz`	`REPNE`	repeat while not equal
`repnz`	`REPNZ`	repeat while not zero
`repz`	`REPE`	repeat while equal
`repz`	`REPZ`	repeat while zero
`scas{q}`	`SCAS`	scan string	`scasq` valid only under `-xarch=amd64`
`scasb`	`SCASB`	scan byte string
`scasl`	`SCASD`	scan doubleword string
`scasw`	`SCASW`	scan word string
`stos{q}`	`STOS`	store string	`stosq` valid only under `-xarch=amd64`
`stosb`	`STOSB`	store byte string
`stosl`	`STOSD`	store doubleword string
`stosw`	`STOSW`	store word string