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/* $OpenBSD: memmove.S,v 1.1 2014/12/04 12:10:26 deraadt Exp $ */
/* $NetBSD: memmove.S,v 1.3 2011/01/15 07:31:12 matt Exp $ */
/* stropt/memmove.S, pl_string_common, pl_linux 10/11/04 11:45:37
* ==========================================================================
* Optimized memmove implementation for IBM PowerPC 405/440.
*
* Copyright (c) 2003, IBM Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* * Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
* * Neither the name of IBM nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ==========================================================================
*/
#include <machine/asm.h>
.text
/* void *memcpy(void *to, const void *from, size_t len) */
// ENTRY(memcpy)
mr %r8, %r3 /* Save dst (return value) */
b fwd
/* void bcopy(void *, void *, size_t) */
ENTRY(bcopy)
mr %r6, %r3 /* swap src/dst */
mr %r3, %r4
mr %r4, %r6
/* void *memmove(void *, const void *, size_t) */
ENTRY(memmove)
mr %r8, %r3 /* Save dst (return value) */
cmpw %r4, %r8 /* Branch to reverse if */
blt reverse /* src < dest. Don't want to */
/* overwrite end of src with */
/* start of dest */
fwd:
addi %r4, %r4, -4 /* Back up src and dst pointers */
addi %r8, %r8, -4 /* due to auto-update of 'load' */
srwi. %r9,%r5,2 /* How many words in total cnt */
beq- last1 /* Handle byte by byte if < 4 */
/* bytes total */
mtctr %r9 /* Count of words for loop */
lwzu %r7, 4(%r4) /* Preload first word */
b g1
g0: /* Main loop */
lwzu %r7, 4(%r4) /* Load a new word */
stwu %r6, 4(%r8) /* Store previous word */
g1:
bdz- last /* Dec cnt, and branch if just */
/* one word to store */
lwzu %r6, 4(%r4) /* Load another word */
stwu %r7, 4(%r8) /* Store previous word */
bdnz+ g0 /* Dec cnt, and loop again if */
/* more words */
mr %r7, %r6 /* If word count -> 0, then... */
last:
stwu %r7, 4(%r8) /* ... store last word */
last1: /* Byte-by-byte copy */
clrlwi. %r5,%r5,30 /* If count -> 0, then ... */
beqlr /* we're done */
mtctr %r5 /* else load count for loop */
lbzu %r6, 4(%r4) /* 1st byte: update addr by 4 */
stbu %r6, 4(%r8) /* since we pre-adjusted by 4 */
bdzlr- /* in anticipation of main loop */
last2:
lbzu %r6, 1(%r4) /* But handle the rest by */
stbu %r6, 1(%r8) /* updating addr by 1 */
bdnz+ last2
blr
/* We're here since src < dest. Don't want to overwrite end of */
/* src with start of dest */
reverse:
add %r4, %r4, %r5 /* Work from end to beginning */
add %r8, %r8, %r5 /* so add count to string ptrs */
srwi. %r9,%r5,2 /* Words in total count */
beq- rlast1 /* Handle byte by byte if < 4 */
/* bytes total */
mtctr %r9 /* Count of words for loop */
lwzu %r7, -4(%r4) /* Preload first word */
b rg1
rg0: /* Main loop */
lwzu %r7, -4(%r4) /* Load a new word */
stwu %r6, -4(%r8) /* Store previous word */
rg1:
bdz- rlast /* Dec cnt, and branch if just */
/* one word to store */
lwzu %r6, -4(%r4) /* Load another word */
stwu %r7, -4(%r8) /* Store previous word */
bdnz+ rg0 /* Dec cnt, and loop again if */
/* more words */
mr %r7, %r6 /* If word count -> 0, then... */
rlast:
stwu %r7, -4(%r8) /* ... store last word */
rlast1: /* Byte-by-byte copy */
clrlwi. %r5,%r5,30 /* If count -> 0, then... */
beqlr /* ... we're done */
mtctr %r5 /* else load count for loop */
rlast2:
lbzu %r6, -1(%r4) /* Handle the rest, byte by */
stbu %r6, -1(%r8) /* byte */
bdnz+ rlast2 /* Dec ctr, and branch if more */
/* bytes left */
blr
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