b6cbf7203b
This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
112 lines
2.1 KiB
ArmAsm
112 lines
2.1 KiB
ArmAsm
/*
|
|
* Written by J.T. Conklin <jtc@acorntoolworks.com>
|
|
* Public domain.
|
|
*/
|
|
|
|
#include <machine/asm.h>
|
|
|
|
#if defined(LIBC_SCCS)
|
|
RCSID("$NetBSD: strcpy.S,v 1.1 2005/12/20 19:28:51 christos Exp $")
|
|
#endif
|
|
|
|
/*
|
|
* This strcpy implementation copies a byte at a time until the
|
|
* source pointer is aligned to a word boundary, it then copies by
|
|
* words until it finds a word containing a zero byte, and finally
|
|
* copies by bytes until the end of the string is reached.
|
|
*
|
|
* While this may result in unaligned stores if the source and
|
|
* destination pointers are unaligned with respect to each other,
|
|
* it is still faster than either byte copies or the overhead of
|
|
* an implementation suitable for machines with strict alignment
|
|
* requirements.
|
|
*/
|
|
|
|
ENTRY(strcpy)
|
|
movq %rdi,%rax
|
|
movabsq $0x0101010101010101,%r8
|
|
movabsq $0x8080808080808080,%r9
|
|
|
|
/*
|
|
* Align source to a word boundary.
|
|
* Consider unrolling loop?
|
|
*/
|
|
_ALIGN_TEXT
|
|
.Lalign:
|
|
testb $7,%sil
|
|
je .Lword_aligned
|
|
movb (%rsi),%dl
|
|
incq %rsi
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl
|
|
jne .Lalign
|
|
ret
|
|
|
|
_ALIGN_TEXT
|
|
.Lloop:
|
|
movq %rdx,(%rdi)
|
|
addq $8,%rdi
|
|
.Lword_aligned:
|
|
movq (%rsi),%rdx
|
|
movq %rdx,%rcx
|
|
addq $8,%rsi
|
|
subq %r8,%rcx
|
|
testq %r9,%rcx
|
|
je .Lloop
|
|
|
|
/*
|
|
* In rare cases, the above loop may exit prematurely. We must
|
|
* return to the loop if none of the bytes in the word equal 0.
|
|
*/
|
|
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 1st byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 2nd byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 3rd byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 4th byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 5th byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 6th byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 7th byte == 0? */
|
|
je .Ldone
|
|
|
|
shrq $8,%rdx
|
|
movb %dl,(%rdi)
|
|
incq %rdi
|
|
testb %dl,%dl /* 8th byte == 0? */
|
|
jne .Lword_aligned
|
|
|
|
.Ldone:
|
|
ret
|