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129 lines
3.4 KiB
ArmAsm
129 lines
3.4 KiB
ArmAsm
/* Optimized strncmp implementation for PowerPC476.
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Copyright (C) 2010-2013 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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/* strncmp
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Register Use
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r0:temp return equality
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r3:source1 address, return equality
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r4:source2 address
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r5:byte count
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Implementation description
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Touch in 3 lines of D-cache.
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If source1 or source2 is unaligned copy 0-3 bytes to make source1 aligned
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Check 2 words from src1 and src2. If unequal jump to end and
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return src1 > src2 or src1 < src2.
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If null check bytes before null and then jump to end and
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return src1 > src2, src1 < src2 or src1 = src2.
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If count = zero check bytes before zero counter and then jump to end and
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return src1 > src2, src1 < src2 or src1 = src2.
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If src1 = src2 and no null, repeat. */
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EALIGN (strncmp,5,0)
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neg r7,r3
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clrlwi r7,r7,20
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neg r8,r4
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clrlwi r8,r8,20
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srwi. r7,r7,3
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beq L(prebyte_count_loop)
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srwi. r8,r8,3
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beq L(prebyte_count_loop)
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cmplw r7,r8
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mtctr r7
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ble L(preword2_count_loop)
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mtctr r8
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L(preword2_count_loop):
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srwi. r6,r5,3
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beq L(prebyte_count_loop)
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mfctr r7
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cmplw r6,r7
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bgt L(set_count_loop)
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mtctr r6
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clrlwi r5,r5,29
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L(word2_count_loop):
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lwz r10,0(r3)
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lwz r6,4(r3)
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addi r3,r3,0x08
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lwz r8,0(r4)
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lwz r9,4(r4)
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addi r4,r4,0x08
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dlmzb. r12,r10,r6
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bne L(end_check)
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cmplw r10,r8
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bne L(st1)
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cmplw r6,r9
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bne L(st1)
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bdnz L(word2_count_loop)
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L(prebyte_count_loop):
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addi r5,r5,1
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mtctr r5
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bdz L(end_strncmp)
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L(byte_count_loop):
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lbz r6,0(r3)
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addi r3,r3,1
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lbz r7,0(r4)
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addi r4,r4,1
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cmplw r6,r7
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bne L(st1)
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cmpwi r6,0
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beq L(end_strncmp)
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bdnz L(byte_count_loop)
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b L(end_strncmp)
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L(set_count_loop):
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slwi r7,r7,3
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subf r5,r7,r5
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b L(word2_count_loop)
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L(end_check):
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subfic r12,r12,4
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blt L(end_check2)
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rlwinm r12,r12,3,0,31
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srw r10,r10,r12
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srw r8,r8,r12
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cmplw r10,r8
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bne L(st1)
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b L(end_strncmp)
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L(end_check2):
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addi r12,r12,4
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cmplw r10,r8
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rlwinm r12,r12,3,0,31
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bne L(st1)
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srw r6,r6,r12
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srw r9,r9,r12
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cmplw r6,r9
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bne L(st1)
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L(end_strncmp):
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addi r3,r0,0
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blr
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L(st1):
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mfcr r3
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blr
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END (strncmp)
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libc_hidden_builtin_def (strncmp)
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