226 lines
5.6 KiB
ArmAsm
226 lines
5.6 KiB
ArmAsm
/* Optimized strcmp implementation for PowerPC64.
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Copyright (C) 2003-2022 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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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#ifndef STRNCMP
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# define STRNCMP strncmp
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#endif
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/* See strlen.s for comments on how the end-of-string testing works. */
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/* int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t size [r5]) */
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ENTRY_TOCLESS (STRNCMP, 4)
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CALL_MCOUNT 3
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#define rTMP2 r0
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#define rRTN r3
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#define rSTR1 r3 /* first string arg */
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#define rSTR2 r4 /* second string arg */
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#define rN r5 /* max string length */
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#define rWORD1 r6 /* current word in s1 */
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#define rWORD2 r7 /* current word in s2 */
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#define rWORD3 r10
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#define rWORD4 r11
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#define rFEFE r8 /* constant 0xfefefefefefefeff (-0x0101010101010101) */
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#define r7F7F r9 /* constant 0x7f7f7f7f7f7f7f7f */
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#define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */
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#define rBITDIF r11 /* bits that differ in s1 & s2 words */
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#define rTMP r12
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dcbt 0,rSTR1
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or rTMP, rSTR2, rSTR1
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lis r7F7F, 0x7f7f
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dcbt 0,rSTR2
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clrldi. rTMP, rTMP, 61
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cmpldi cr1, rN, 0
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lis rFEFE, -0x101
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bne L(unaligned)
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/* We are doubleword aligned so set up for two loops. first a double word
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loop, then fall into the byte loop if any residual. */
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srdi. rTMP, rN, 3
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clrldi rN, rN, 61
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addi rFEFE, rFEFE, -0x101
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addi r7F7F, r7F7F, 0x7f7f
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cmpldi cr1, rN, 0
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beq L(unaligned)
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mtctr rTMP /* Power4 wants mtctr 1st in dispatch group. */
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ld rWORD1, 0(rSTR1)
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ld rWORD2, 0(rSTR2)
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sldi rTMP, rFEFE, 32
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insrdi r7F7F, r7F7F, 32, 0
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add rFEFE, rFEFE, rTMP
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b L(g1)
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L(g0):
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ldu rWORD1, 8(rSTR1)
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bne- cr1, L(different)
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ldu rWORD2, 8(rSTR2)
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L(g1): add rTMP, rFEFE, rWORD1
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nor rNEG, r7F7F, rWORD1
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bdz L(tail)
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and. rTMP, rTMP, rNEG
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cmpd cr1, rWORD1, rWORD2
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beq+ L(g0)
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/* OK. We've hit the end of the string. We need to be careful that
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we don't compare two strings as different because of gunk beyond
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the end of the strings... */
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#ifdef __LITTLE_ENDIAN__
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L(endstring):
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addi rTMP2, rTMP, -1
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beq cr1, L(equal)
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andc rTMP2, rTMP2, rTMP
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rldimi rTMP2, rTMP2, 1, 0
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and rWORD2, rWORD2, rTMP2 /* Mask off gunk. */
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and rWORD1, rWORD1, rTMP2
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cmpd cr1, rWORD1, rWORD2
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beq cr1, L(equal)
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xor rBITDIF, rWORD1, rWORD2 /* rBITDIF has bits that differ. */
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neg rNEG, rBITDIF
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and rNEG, rNEG, rBITDIF /* rNEG has LS bit that differs. */
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cntlzd rNEG, rNEG /* bitcount of the bit. */
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andi. rNEG, rNEG, 56 /* bitcount to LS byte that differs. */
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sld rWORD1, rWORD1, rNEG /* shift left to clear MS bytes. */
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sld rWORD2, rWORD2, rNEG
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xor. rBITDIF, rWORD1, rWORD2
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sub rRTN, rWORD1, rWORD2
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blt- L(highbit)
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sradi rRTN, rRTN, 63 /* must return an int. */
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ori rRTN, rRTN, 1
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blr
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L(equal):
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li rRTN, 0
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blr
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L(different):
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ld rWORD1, -8(rSTR1)
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xor rBITDIF, rWORD1, rWORD2 /* rBITDIF has bits that differ. */
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neg rNEG, rBITDIF
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and rNEG, rNEG, rBITDIF /* rNEG has LS bit that differs. */
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cntlzd rNEG, rNEG /* bitcount of the bit. */
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andi. rNEG, rNEG, 56 /* bitcount to LS byte that differs. */
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sld rWORD1, rWORD1, rNEG /* shift left to clear MS bytes. */
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sld rWORD2, rWORD2, rNEG
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xor. rBITDIF, rWORD1, rWORD2
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sub rRTN, rWORD1, rWORD2
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blt- L(highbit)
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sradi rRTN, rRTN, 63
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ori rRTN, rRTN, 1
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blr
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L(highbit):
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sradi rRTN, rWORD2, 63
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ori rRTN, rRTN, 1
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blr
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#else
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L(endstring):
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and rTMP, r7F7F, rWORD1
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beq cr1, L(equal)
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add rTMP, rTMP, r7F7F
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xor. rBITDIF, rWORD1, rWORD2
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andc rNEG, rNEG, rTMP
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blt- L(highbit)
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cntlzd rBITDIF, rBITDIF
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cntlzd rNEG, rNEG
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addi rNEG, rNEG, 7
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cmpd cr1, rNEG, rBITDIF
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sub rRTN, rWORD1, rWORD2
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blt- cr1, L(equal)
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sradi rRTN, rRTN, 63 /* must return an int. */
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ori rRTN, rRTN, 1
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blr
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L(equal):
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li rRTN, 0
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blr
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L(different):
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ld rWORD1, -8(rSTR1)
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xor. rBITDIF, rWORD1, rWORD2
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sub rRTN, rWORD1, rWORD2
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blt- L(highbit)
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sradi rRTN, rRTN, 63
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ori rRTN, rRTN, 1
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blr
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L(highbit):
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sradi rRTN, rWORD2, 63
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ori rRTN, rRTN, 1
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blr
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#endif
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/* Oh well. In this case, we just do a byte-by-byte comparison. */
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.align 4
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L(tail):
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and. rTMP, rTMP, rNEG
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cmpd cr1, rWORD1, rWORD2
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bne- L(endstring)
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addi rSTR1, rSTR1, 8
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bne- cr1, L(different)
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addi rSTR2, rSTR2, 8
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cmpldi cr1, rN, 0
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L(unaligned):
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mtctr rN /* Power4 wants mtctr 1st in dispatch group */
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ble cr1, L(ux)
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L(uz):
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lbz rWORD1, 0(rSTR1)
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lbz rWORD2, 0(rSTR2)
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.align 4
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L(u1):
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cmpdi cr1, rWORD1, 0
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bdz L(u4)
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cmpd rWORD1, rWORD2
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beq- cr1, L(u4)
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bne- L(u4)
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lbzu rWORD3, 1(rSTR1)
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lbzu rWORD4, 1(rSTR2)
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cmpdi cr1, rWORD3, 0
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bdz L(u3)
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cmpd rWORD3, rWORD4
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beq- cr1, L(u3)
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bne- L(u3)
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lbzu rWORD1, 1(rSTR1)
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lbzu rWORD2, 1(rSTR2)
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cmpdi cr1, rWORD1, 0
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bdz L(u4)
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cmpd rWORD1, rWORD2
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beq- cr1, L(u4)
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bne- L(u4)
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lbzu rWORD3, 1(rSTR1)
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lbzu rWORD4, 1(rSTR2)
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cmpdi cr1, rWORD3, 0
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bdz L(u3)
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cmpd rWORD3, rWORD4
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beq- cr1, L(u3)
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bne- L(u3)
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lbzu rWORD1, 1(rSTR1)
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lbzu rWORD2, 1(rSTR2)
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b L(u1)
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L(u3): sub rRTN, rWORD3, rWORD4
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blr
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L(u4): sub rRTN, rWORD1, rWORD2
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blr
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L(ux):
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li rRTN, 0
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blr
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END (STRNCMP)
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libc_hidden_builtin_def (strncmp)
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