Lionel Sambuc 0a6a1f1d05 NetBSD re-synchronization of the source tree
This brings our tree to NetBSD 7.0, as found on -current on the
10-10-2015.

This updates:
 - LLVM to 3.6.1
 - GCC to GCC 5.1
 - Replace minix/commands/zdump with usr.bin/zdump
 - external/bsd/libelf has moved to /external/bsd/elftoolchain/
 - Import ctwm
 - Drop sprintf from libminc

Change-Id: I149836ac18e9326be9353958bab9b266efb056f0
2016-01-13 20:32:14 +01:00

70 lines
1.1 KiB
ArmAsm

/*
* Written by J.T. Conklin <jtc@NetBSD.org>.
* Public domain.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: swab.S,v 1.14 2014/05/23 02:34:19 uebayasi Exp $")
#endif
/*
* On the i486, this code is negligibly faster than the code generated
* by gcc at about half the size. If my i386 databook is correct, it
* should be considerably faster than the gcc code on a i386.
*/
ENTRY(swab)
pushl %esi
pushl %edi
movl 12(%esp),%esi
movl 16(%esp),%edi
movl 20(%esp),%ecx
shrl $1,%ecx
testl $7,%ecx # copy first group of 1 to 7 words
jz L2 # while swapping alternate bytes.
_ALIGN_TEXT,0x90
L1: lodsw
rorw $8,%ax
stosw
decl %ecx
testl $7,%ecx
jnz L1
L2: shrl $3,%ecx # copy remainder 8 words at a time
jz L4 # while swapping alternate bytes.
_ALIGN_TEXT,0x90
L3: lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
lodsw
rorw $8,%ax
stosw
decl %ecx
jnz L3
L4: popl %edi
popl %esi
ret
END(swab)