NetBSD/lib/libc/arch/m68k/string/swab.S

/*	$NetBSD: swab.S,v 1.7 1999/10/25 23:48:16 thorpej Exp $	*/

#include <machine/asm.h>

ENTRY(swab)
	movl	%sp@(4),%a0		| source
	movl	%sp@(8),%a1		| destination
	movl	%sp@(12),%d0		| count
	lsrl	#1,%d0			| count is in bytes; we need words
	jeq	swdone

swloop:
	movw	%a0@+,%d1
	rorw	#8,%d1
	movw	%d1,%a1@+
	subql	#1,%d0
	jne	swloop

swdone:
	rts
Add register prefixes. 1999-10-26 03:48:07 +04:00			`/* $NetBSD: swab.S,v 1.7 1999/10/25 23:48:16 thorpej Exp $ */`
New style RCS ids, and employ the RCSID() macro. 1995-11-17 23:21:10 +03:00
#include <machine/asm.h> instead of "DEFS.h" 1997-01-04 06:26:18 +03:00			`#include <machine/asm.h>`
Assembler version. 1993-12-07 02:16:05 +03:00
			`ENTRY(swab)`
Add register prefixes. 1999-10-26 03:48:07 +04:00			`movl %sp@(4),%a0 \| source`
			`movl %sp@(8),%a1 \| destination`
			`movl %sp@(12),%d0 \| count`
			`lsrl #1,%d0 \| count is in bytes; we need words`
Use jCC instead of bCC, as the assembler will then use the (smaller, faster) byte-displacement form of the instruction if the offset will fit. This happens to be all occurances in this case, so I could have used bCCs. However, a quick survey of the rest of NetBSD's m68k code showed that jCC was used in similar cases. I did the same to be consistant. 1997-01-04 06:21:11 +03:00			`jeq swdone`
Assembler version. 1993-12-07 02:16:05 +03:00
			`swloop:`
Add register prefixes. 1999-10-26 03:48:07 +04:00			`movw %a0@+,%d1`
			`rorw #8,%d1`
			`movw %d1,%a1@+`
			`subql #1,%d0`
Use jCC instead of bCC, as the assembler will then use the (smaller, faster) byte-displacement form of the instruction if the offset will fit. This happens to be all occurances in this case, so I could have used bCCs. However, a quick survey of the rest of NetBSD's m68k code showed that jCC was used in similar cases. I did the same to be consistant. 1997-01-04 06:21:11 +03:00			`jne swloop`
Assembler version. 1993-12-07 02:16:05 +03:00
			`swdone:`
			`rts`