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Cygwin: x86_64: import swab.S from NetBSD 

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2022-12-20 10:19:23 +01:00
parent 43743ed754
commit 2af7dd9567
2 changed files with 48 additions and 0 deletions
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1
winsup/cygwin/Makefile.am
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@ -58,6 +58,7 @@ TARGET_FILES= \
x86_64/memmove.S \
x86_64/mempcpy.S \
x86_64/memset.S \
x86_64/swab.S \
x86_64/wmemcpy.S \
x86_64/wmemmove.S \
x86_64/wmempcpy.S

47
winsup/cygwin/x86_64/swab.S Normal file
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@ -0,0 +1,47 @@
/*
* Written by J.T. Conklin <jtc@NetBSD.org>.
* Public domain.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: swab.S,v 1.4 2014/05/22 15:01:57 uebayasi Exp $")
#endif
#define LOAD_SWAP_STORE_WORD \
lodsw ; \
xchgb %al,%ah ; \
stosw
ENTRY3(swab)
xchgq %rdi,%rsi
cld # set direction forward
shrq $1,%rdx
testq $7,%rdx # copy first group of 1 to 7 words
jz L2 # while swapping alternate bytes.
L1: lodsw
rorw $8,%ax
stosw
decq %rdx
testq $7,%rdx
jnz L1
L2: shrq $3,%rdx # copy remainder 8 words at a time
jz L4 # while swapping alternate bytes.
L3:
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
LOAD_SWAP_STORE_WORD
decq %rdx
jnz L3
L4:
ret
END(swab)