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/* Optimized strcpy/stpcpy implementation for PowerPC64/POWER7.
Copyright (C) 2013-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* Implements the function
char * [r3] strcpy (char *dest [r3], const char *src [r4])
or
char * [r3] strcpy (char *dest [r3], const char *src [r4])
if USE_AS_STPCPY is defined. It tries to use aligned memory accesses
when possible using the following algorithm:
if (((((uintptr_t)dst & 0x7UL) == 0) && ((uintptr_t)src & 0x7UL) == 0))
goto aligned_doubleword_copy;
if (((uintptr_t)dst & 0x7UL) == ((uintptr_t)src & 0x7UL))
goto same_alignment;
goto unaligned;
The aligned comparison are made using cmpb instructions. */
#ifdef USE_AS_STPCPY
# define FUNC_NAME __stpcpy
#else
# define FUNC_NAME strcpy
#endif
.machine power7
EALIGN (FUNC_NAME, 4, 0)
CALL_MCOUNT 2
#define rTMP r0
#ifdef USE_AS_STPCPY
#define rRTN r3 /* pointer to previous word/doubleword in dest */
#else
#define rRTN r12 /* pointer to previous word/doubleword in dest */
#endif
#define rSRC r4 /* pointer to previous word/doubleword in src */
#define rMASK r5 /* mask 0xffffffff | 0xffffffffffffffff */
#define rWORD r6 /* current word from src */
#define rALT r7 /* alternate word from src */
#define rRTNAL r8 /* alignment of return pointer */
#define rSRCAL r9 /* alignment of source pointer */
#define rALCNT r10 /* bytes to read to reach 8 bytes alignment */
#define rSUBAL r11 /* doubleword minus unaligned displacement */
#ifndef USE_AS_STPCPY
/* Save the dst pointer to use as return value. */
mr rRTN, r3
#endif
or rTMP, rSRC, rRTN
clrldi. rTMP, rTMP, 61
bne L(check_alignment)
b L(aligned_doubleword_copy)
.align 4
L(check_alignment):
rldicl rRTNAL, rRTN, 0, 61
rldicl rSRCAL, rSRC, 0, 61
cmpld cr7, rSRCAL, rRTNAL
beq cr7, L(same_alignment)
b L(unaligned)
.align 4
L(same_alignment):
/* Src and dst with same alignment: align both to doubleword. */
mr rALCNT, rRTN
lbz rWORD, 0(rSRC)
subfic rSUBAL, rRTNAL, 8
addi rRTN, rRTN, 1
addi rSRC, rSRC, 1
cmpdi cr7, rWORD, 0
stb rWORD, 0(rALCNT)
beq cr7, L(s2)
add rALCNT, rALCNT, rSUBAL
subf rALCNT, rRTN, rALCNT
addi rALCNT, rALCNT, 1
mtctr rALCNT
b L(s1)
.align 4
L(s0):
addi rSRC, rSRC, 1
lbz rWORD, -1(rSRC)
cmpdi cr7, rWORD, 0
stb rWORD, -1(rALCNT)
beqlr cr7
mr rRTN, rALCNT
L(s1):
addi rALCNT, rRTN,1
bdnz L(s0)
b L(aligned_doubleword_copy)
.align 4
L(s2):
mr rRTN, rALCNT
blr
/* For doubleword aligned memory, operate using doubleword load and stores. */
.align 4
L(aligned_doubleword_copy):
li rMASK, 0
addi rRTN, rRTN, -8
ld rWORD, 0(rSRC)
b L(g2)
.align 4
L(g0): ldu rALT, 8(rSRC)
stdu rWORD, 8(rRTN)
cmpb rTMP, rALT, rMASK
cmpdi rTMP, 0
bne L(g1)
ldu rWORD, 8(rSRC)
stdu rALT, 8(rRTN)
L(g2): cmpb rTMP, rWORD, rMASK
cmpdi rTMP, 0 /* If rTMP is 0, no null's have been found. */
beq L(g0)
mr rALT, rWORD
/* We've hit the end of the string. Do the rest byte-by-byte. */
L(g1):
#ifdef __LITTLE_ENDIAN__
extrdi. rTMP, rALT, 8, 56
stbu rALT, 8(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 48
stbu rTMP, 1(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 40
stbu rTMP, 1(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 32
stbu rTMP, 1(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 24
stbu rTMP, 1(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 16
stbu rTMP, 1(rRTN)
beqlr-
extrdi. rTMP, rALT, 8, 8
stbu rTMP, 1(rRTN)
beqlr-
extrdi rTMP, rALT, 8, 0
stbu rTMP, 1(rRTN)
#else
extrdi. rTMP, rALT, 8, 0
stbu rTMP, 8(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 8
stbu rTMP, 1(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 16
stbu rTMP, 1(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 24
stbu rTMP, 1(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 32
stbu rTMP, 1(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 40
stbu rTMP, 1(rRTN)
beqlr
extrdi. rTMP, rALT, 8, 48
stbu rTMP, 1(rRTN)
beqlr
stbu rALT, 1(rRTN)
#endif
blr
.align 4
L(unaligned):
cmpdi rSRCAL, 0 /* Check src alignment */
beq L(srcaligndstunalign)
/* src is unaligned */
rlwinm r10, rSRC, 3,26,28 /* Calculate padding. */
clrrdi rSRC, rSRC, 3 /* Align the addr to dw boundary */
ld rWORD, 0(rSRC) /* Load doubleword from memory. */
li rTMP, 0
/* Discard bits not part of the string */
#ifdef __LITTLE_ENDIAN__
srd rALT, rWORD, r10
#else
sld rALT, rWORD, r10
#endif
cmpb rTMP, rALT, rTMP /* Compare each byte against null */
/* Discard bits not part of the string */
#ifdef __LITTLE_ENDIAN__
sld rTMP, rTMP, r10
#else
srd rTMP, rTMP, r10
#endif
cmpdi rTMP, 0
bne L(bytebybyte) /* if it has null, copy byte by byte */
subfic r8, r9, 8
rlwinm r5, rRTN, 3,26,28 /* Calculate padding in bits. */
rldicl r9, rRTN, 0, 61 /* Calculate padding in bytes. */
addi rRTN, rRTN, -1
cmpdi r5, 0 /* check dest alignment */
beq L(srcunaligndstalign)
/* both src and dst unaligned */
#ifdef __LITTLE_ENDIAN__
sld rWORD, rALT, r10
mr r11, r10
addi r11, r11, -8 /* Adjust byte pointer on loaded dw */
#else
srd rWORD, rALT, r10
subfic r11, r10, 64
#endif
/* dst alignment is greater then src alignment? */
cmpd cr7, r5, r10
blt cr7, L(dst_align_small)
/* src alignment is less than dst */
/* Calculate the dst alignment differnce */
subfic rALT, r9, 8
mtctr rALT
/* Write till dst is aligned */
cmpdi rTMP, rALT, 4
blt L(storebyte1) /* less than 4, store byte by byte */
beq L(equal1) /* if its 4, store word */
addi rTMP, rALT, -4 /* greater than 4, so stb and stw */
mtctr rTMP
L(storebyte1):
#ifdef __LITTLE_ENDIAN__
addi r11, r11, 8 /* Adjust byte pointer on loaded dw */
#else
addi r11, r11, -8
#endif
srd rALT, rWORD, r11
stbu rALT, 1(rRTN)
bdnz L(storebyte1)
subfic rALT, r9, 8 /* Check the remaining bytes */
cmpdi rTMP, rALT, 4
blt L(proceed)
.align 4
L(equal1):
#ifdef __LITTLE_ENDIAN__
addi r11, r11, 8 /* Adjust byte pointer on loaded dw */
srd rALT, rWORD, r11
#else
subfic r11, r11, 64
sld rALT, rWORD, r11
srdi rALT, rALT, 32
#endif
stw rALT, 1(rRTN)
addi rRTN, rRTN, 4
L(proceed):
mr rALT, rWORD
/* calculate the Left over bytes to be written */
subfic r11, r10, 64
subfic r5, r5, 64
subf r5, r5, r11 /* remaining bytes on second dw */
subfic r10, r5, 64 /* remaining bytes on first dw */
subfic r9, r9, 8
subf r8, r9, r8 /* recalculate padding */
L(srcunaligndstalign):
addi rRTN, rRTN, 1
subfic r5, r10, 64 /* remaining bytes on second dw */
addi rSRC, rSRC, 8
li rTMP,0
b L(storedouble)
.align 4
L(dst_align_small):
mtctr r8
/* Write till src is aligned */
L(storebyte2):
#ifdef __LITTLE_ENDIAN__
addi r11, r11, 8 /* Adjust byte pointer on dw */
#else
addi r11, r11, -8
#endif
srd rALT, rWORD, r11
stbu rALT, 1(rRTN)
bdnz L(storebyte2)
addi rSRC, rSRC, 8 /* Increment src pointer */
addi rRTN, rRTN, 1 /* Increment dst pointer */
rldicl r8, rRTN, 0, 61 /* Recalculate padding */
/* src is aligned */
L(srcaligndstunalign):
ld rWORD, 0(rSRC)
mr rALT, rWORD
li rTMP, 0 /* Check null */
cmpb rTMP, rWORD, rTMP
cmpdi rTMP, 0
bne L(bytebybyte) /* Do byte by byte if there is NULL */
rlwinm r5, rRTN, 3,26,28 /* Calculate padding */
addi rRTN, rRTN, -1
subfic r10, r8, 8
/* write byte by byte till aligned */
#ifdef __LITTLE_ENDIAN__
li r11, -8
#else
li r11, 64
#endif
mtctr r10
cmpdi rTMP, r10, 4
blt L(storebyte)
beq L(equal)
addi rTMP, r10, -4
mtctr rTMP
L(storebyte):
#ifdef __LITTLE_ENDIAN__
addi r11, r11, 8 /* Adjust byte pointer on dw */
#else
addi r11, r11, -8
#endif
srd rALT, rWORD, r11
stbu rALT, 1(rRTN)
bdnz L(storebyte)
cmpdi rTMP, r10, 4
blt L(align)
.align 4
L(equal):
#ifdef __LITTLE_ENDIAN__
addi r11, r11, 8
srd rALT, rWORD, r11
#else
subfic r11, r11, 64
sld rALT, rWORD, r11
srdi rALT, rALT, 32
#endif
stw rALT, 1(rRTN)
addi rRTN, rRTN, 4
L(align):
addi rRTN, rRTN, 1
addi rSRC, rSRC, 8 /* Increment src pointer */
subfic r10, r5, 64
li rTMP, 0
/* dst addr aligned to 8 */
L(storedouble):
ld rALT, 0(rSRC) /* load next dw */
cmpb rTMP, rALT, rTMP
cmpdi rTMP, 0 /* check for null on each new dw */
bne L(null)
#ifdef __LITTLE_ENDIAN__
srd r9, rWORD, r10 /* bytes from first dw */
sld r11, rALT, r5 /* bytes from second dw */
#else
sld r9, rWORD, r10
srd r11, rALT, r5
#endif
or r11, r9, r11 /* make as a single dw */
std r11, 0(rRTN) /* store as std on aligned addr */
mr rWORD, rALT /* still few bytes left to be written */
addi rRTN, rRTN, 8 /* increment dst addr */
addi rSRC, rSRC, 8 /* increment src addr */
b L(storedouble) /* Loop till NULL */
.align 4
/* We've hit the end of the string. Do the rest byte-by-byte. */
L(null):
addi rRTN, rRTN, -1
mr r10, r5
mtctr r8
#ifdef __LITTLE_ENDIAN__
subfic r10, r10, 64
addi r10, r10, -8
#endif
cmpdi rTMP, r8, 4
blt L(loop)
/* we can still use stw if leftover >= 4*/
#ifdef __LITTLE_ENDIAN__
addi r10, r10, 8
srd r11, rWORD, r10
#else
subfic r10, r10, 64
sld r11, rWORD, r10
srdi r11, r11, 32
#endif
stw r11, 1(rRTN)
addi rRTN, rRTN, 4
beq L(bytebybyte1)
addi r10, r10, 32
#ifdef __LITTLE_ENDIAN__
addi r10, r10, -8
#else
subfic r10, r10, 64
#endif
addi rTMP, r8, -4
mtctr rTMP
/* remaining byte by byte part of first dw */
L(loop):
#ifdef __LITTLE_ENDIAN__
addi r10, r10, 8
#else
addi r10, r10, -8
#endif
srd rTMP, rWORD, r10
stbu rTMP, 1(rRTN)
bdnz L(loop)
L(bytebybyte1):
addi rRTN, rRTN, 1
/* remaining byte by byte part of second dw */
L(bytebybyte):
addi rRTN, rRTN, -8
b L(g1)
END (FUNC_NAME)
#ifndef USE_AS_STPCPY
libc_hidden_builtin_def (strcpy)
#endif
|
