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426 lines
11 KiB
ArmAsm
426 lines
11 KiB
ArmAsm
/* Optimized memcpy implementation for PowerPC32 on PowerPC64.
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Copyright (C) 2003, 2006, 2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <bp-sym.h>
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#include <bp-asm.h>
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/* __ptr_t [r3] memcpy (__ptr_t dst [r3], __ptr_t src [r4], size_t len [r5]);
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Returns 'dst'.
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Memcpy handles short copies (< 32-bytes) using a binary move blocks
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(no loops) of lwz/stw. The tail (remaining 1-3) bytes is handled
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with the appropriate combination of byte and halfword load/stores.
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There is minimal effort to optimize the alignment of short moves.
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Longer moves (>= 32-bytes) justify the effort to get at least the
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destination word (4-byte) aligned. Further optimization is
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possible when both source and destination are word aligned.
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Each case has an optimized unrolled loop. */
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.machine power4
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EALIGN (BP_SYM (memcpy), 5, 0)
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CALL_MCOUNT
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stwu 1,-32(1)
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cfi_adjust_cfa_offset(32)
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stw 30,20(1)
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cfi_offset(30,(20-32))
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mr 30,3
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cmplwi cr1,5,31
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stw 31,24(1)
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cfi_offset(31,(24-32))
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neg 0,3
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andi. 11,3,3 /* check alignment of dst. */
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clrlwi 0,0,30 /* Number of bytes until the 1st word of dst. */
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clrlwi 10,4,30 /* check alignment of src. */
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cmplwi cr6,5,8
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ble- cr1,.L2 /* If move < 32 bytes use short move code. */
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cmplw cr6,10,11
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mr 12,4
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srwi 9,5,2 /* Number of full words remaining. */
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mtcrf 0x01,0
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mr 31,5
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beq .L0
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subf 31,0,5
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/* Move 0-3 bytes as needed to get the destination word aligned. */
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1: bf 31,2f
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lbz 6,0(12)
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addi 12,12,1
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stb 6,0(3)
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addi 3,3,1
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2: bf 30,0f
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lhz 6,0(12)
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addi 12,12,2
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sth 6,0(3)
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addi 3,3,2
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0:
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clrlwi 10,12,30 /* check alignment of src again. */
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srwi 9,31,2 /* Number of full words remaining. */
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/* Copy words from source to destination, assuming the destination is
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aligned on a word boundary.
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At this point we know there are at least 25 bytes left (32-7) to copy.
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The next step is to determine if the source is also word aligned.
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If not branch to the unaligned move code at .L6. which uses
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a load, shift, store strategy.
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Otherwise source and destination are word aligned, and we can use
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the optimized word copy loop. */
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.L0:
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clrlwi 11,31,30 /* calculate the number of tail bytes */
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mtcrf 0x01,9
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bne- cr6,.L6 /* If source is not word aligned. */
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/* Move words where destination and source are word aligned.
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Use an unrolled loop to copy 4 words (16-bytes) per iteration.
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If the copy is not an exact multiple of 16 bytes, 1-3
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words are copied as needed to set up the main loop. After
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the main loop exits there may be a tail of 1-3 bytes. These bytes are
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copied a halfword/byte at a time as needed to preserve alignment. */
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srwi 8,31,4 /* calculate the 16 byte loop count */
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cmplwi cr1,9,4
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cmplwi cr6,11,0
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mr 11,12
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bf 30,1f
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lwz 6,0(12)
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lwz 7,4(12)
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addi 11,12,8
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mtctr 8
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stw 6,0(3)
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stw 7,4(3)
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addi 10,3,8
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bf 31,4f
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lwz 0,8(12)
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stw 0,8(3)
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blt cr1,3f
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addi 11,12,12
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addi 10,3,12
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b 4f
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.align 4
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1:
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mr 10,3
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mtctr 8
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bf 31,4f
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lwz 6,0(12)
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addi 11,12,4
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stw 6,0(3)
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addi 10,3,4
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.align 4
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4:
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lwz 6,0(11)
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lwz 7,4(11)
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lwz 8,8(11)
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lwz 0,12(11)
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stw 6,0(10)
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stw 7,4(10)
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stw 8,8(10)
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stw 0,12(10)
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addi 11,11,16
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addi 10,10,16
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bdnz 4b
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3:
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clrrwi 0,31,2
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mtcrf 0x01,31
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beq cr6,0f
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.L9:
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add 3,3,0
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add 12,12,0
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/* At this point we have a tail of 0-3 bytes and we know that the
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destination is word aligned. */
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2: bf 30,1f
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lhz 6,0(12)
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addi 12,12,2
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sth 6,0(3)
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addi 3,3,2
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1: bf 31,0f
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lbz 6,0(12)
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stb 6,0(3)
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0:
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/* Return original dst pointer. */
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mr 3,30
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lwz 30,20(1)
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lwz 31,24(1)
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addi 1,1,32
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blr
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/* Copy up to 31 bytes. This is divided into two cases 0-8 bytes and
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9-31 bytes. Each case is handled without loops, using binary
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(1,2,4,8) tests.
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In the short (0-8 byte) case no attempt is made to force alignment
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of either source or destination. The hardware will handle the
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unaligned load/stores with small delays for crossing 32- 64-byte, and
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4096-byte boundaries. Since these short moves are unlikely to be
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unaligned or cross these boundaries, the overhead to force
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alignment is not justified.
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The longer (9-31 byte) move is more likely to cross 32- or 64-byte
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boundaries. Since only loads are sensitive to the 32-/64-byte
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boundaries it is more important to align the source than the
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destination. If the source is not already word aligned, we first
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move 1-3 bytes as needed. While the destination and stores may
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still be unaligned, this is only an issue for page (4096 byte
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boundary) crossing, which should be rare for these short moves.
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The hardware handles this case automatically with a small delay. */
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.align 4
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.L2:
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mtcrf 0x01,5
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neg 8,4
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clrrwi 11,4,2
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andi. 0,8,3
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ble cr6,.LE8 /* Handle moves of 0-8 bytes. */
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/* At least 9 bytes left. Get the source word aligned. */
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cmplwi cr1,5,16
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mr 10,5
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mr 12,4
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cmplwi cr6,0,2
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beq .L3 /* If the source is already word aligned skip this. */
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/* Copy 1-3 bytes to get source address word aligned. */
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lwz 6,0(11)
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subf 10,0,5
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add 12,4,0
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blt cr6,5f
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srwi 7,6,16
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bgt cr6,3f
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sth 6,0(3)
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b 7f
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.align 4
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3:
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stb 7,0(3)
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sth 6,1(3)
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b 7f
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.align 4
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5:
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stb 6,0(3)
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7:
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cmplwi cr1,10,16
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add 3,3,0
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mtcrf 0x01,10
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.align 4
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.L3:
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/* At least 6 bytes left and the source is word aligned. */
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blt cr1,8f
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16: /* Move 16 bytes. */
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lwz 6,0(12)
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lwz 7,4(12)
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stw 6,0(3)
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lwz 6,8(12)
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stw 7,4(3)
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lwz 7,12(12)
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addi 12,12,16
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stw 6,8(3)
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stw 7,12(3)
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addi 3,3,16
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8: /* Move 8 bytes. */
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bf 28,4f
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lwz 6,0(12)
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lwz 7,4(12)
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addi 12,12,8
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stw 6,0(3)
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stw 7,4(3)
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addi 3,3,8
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4: /* Move 4 bytes. */
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bf 29,2f
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lwz 6,0(12)
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addi 12,12,4
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stw 6,0(3)
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addi 3,3,4
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2: /* Move 2-3 bytes. */
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bf 30,1f
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lhz 6,0(12)
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sth 6,0(3)
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bf 31,0f
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lbz 7,2(12)
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stb 7,2(3)
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mr 3,30
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lwz 30,20(1)
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addi 1,1,32
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blr
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1: /* Move 1 byte. */
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bf 31,0f
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lbz 6,0(12)
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stb 6,0(3)
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0:
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/* Return original dst pointer. */
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mr 3,30
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lwz 30,20(1)
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addi 1,1,32
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blr
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/* Special case to copy 0-8 bytes. */
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.align 4
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.LE8:
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mr 12,4
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bne cr6,4f
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lwz 6,0(4)
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lwz 7,4(4)
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stw 6,0(3)
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stw 7,4(3)
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/* Return original dst pointer. */
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mr 3,30
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lwz 30,20(1)
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addi 1,1,32
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blr
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.align 4
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4: bf 29,2b
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lwz 6,0(4)
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stw 6,0(3)
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6:
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bf 30,5f
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lhz 7,4(4)
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sth 7,4(3)
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bf 31,0f
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lbz 8,6(4)
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stb 8,6(3)
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mr 3,30
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lwz 30,20(1)
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addi 1,1,32
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blr
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.align 4
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5:
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bf 31,0f
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lbz 6,4(4)
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stb 6,4(3)
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.align 4
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0:
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/* Return original dst pointer. */
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mr 3,30
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lwz 30,20(1)
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addi 1,1,32
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blr
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.align 4
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.L6:
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/* Copy words where the destination is aligned but the source is
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not. Use aligned word loads from the source, shifted to realign
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the data, to allow aligned destination stores.
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Use an unrolled loop to copy 4 words (16-bytes) per iteration.
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A single word is retained for storing at loop exit to avoid walking
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off the end of a page within the loop.
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If the copy is not an exact multiple of 16 bytes, 1-3
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words are copied as needed to set up the main loop. After
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the main loop exits there may be a tail of 1-3 bytes. These bytes are
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copied a halfword/byte at a time as needed to preserve alignment. */
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cmplwi cr6,11,0 /* are there tail bytes left ? */
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subf 5,10,12 /* back up src pointer to prev word alignment */
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slwi 10,10,3 /* calculate number of bits to shift 1st word left */
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addi 11,9,-1 /* we move one word after the loop */
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srwi 8,11,2 /* calculate the 16 byte loop count */
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lwz 6,0(5) /* load 1st src word into R6 */
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mr 4,3
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lwz 7,4(5) /* load 2nd src word into R7 */
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mtcrf 0x01,11
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subfic 9,10,32 /* number of bits to shift 2nd word right */
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mtctr 8
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bf 30,1f
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/* there are at least two words to copy, so copy them */
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slw 0,6,10 /* shift 1st src word to left align it in R0 */
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srw 8,7,9 /* shift 2nd src word to right align it in R8 */
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or 0,0,8 /* or them to get word to store */
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lwz 6,8(5) /* load the 3rd src word */
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stw 0,0(4) /* store the 1st dst word */
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slw 0,7,10 /* now left align 2nd src word into R0 */
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srw 8,6,9 /* shift 3rd src word to right align it in R8 */
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or 0,0,8 /* or them to get word to store */
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lwz 7,12(5)
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stw 0,4(4) /* store the 2nd dst word */
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addi 4,4,8
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addi 5,5,16
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bf 31,4f
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/* there is a third word to copy, so copy it */
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slw 0,6,10 /* shift 3rd src word to left align it in R0 */
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srw 8,7,9 /* shift 4th src word to right align it in R8 */
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or 0,0,8 /* or them to get word to store */
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stw 0,0(4) /* store 3rd dst word */
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mr 6,7
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lwz 7,0(5)
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addi 5,5,4
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addi 4,4,4
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b 4f
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.align 4
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1:
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slw 0,6,10 /* shift 1st src word to left align it in R0 */
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srw 8,7,9 /* shift 2nd src word to right align it in R8 */
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addi 5,5,8
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or 0,0,8 /* or them to get word to store */
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bf 31,4f
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mr 6,7
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lwz 7,0(5)
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addi 5,5,4
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stw 0,0(4) /* store the 1st dst word */
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addi 4,4,4
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.align 4
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4:
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/* copy 16 bytes at a time */
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slw 0,6,10
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srw 8,7,9
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or 0,0,8
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lwz 6,0(5)
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stw 0,0(4)
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slw 0,7,10
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srw 8,6,9
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or 0,0,8
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lwz 7,4(5)
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stw 0,4(4)
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slw 0,6,10
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srw 8,7,9
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or 0,0,8
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lwz 6,8(5)
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stw 0,8(4)
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slw 0,7,10
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srw 8,6,9
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or 0,0,8
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lwz 7,12(5)
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stw 0,12(4)
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addi 5,5,16
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addi 4,4,16
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bdnz+ 4b
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8:
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/* calculate and store the final word */
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slw 0,6,10
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srw 8,7,9
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or 0,0,8
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stw 0,0(4)
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3:
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clrrwi 0,31,2
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mtcrf 0x01,31
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bne cr6,.L9 /* If the tail is 0 bytes we are done! */
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/* Return original dst pointer. */
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mr 3,30
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lwz 30,20(1)
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lwz 31,24(1)
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addi 1,1,32
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blr
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END (BP_SYM (memcpy))
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libc_hidden_builtin_def (memcpy)
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