| /* Optimized strncmp implementation for PowerPC476. |
| Copyright (C) 2010-2014 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> |
| |
| /* strncmp |
| |
| Register Use |
| r0:temp return equality |
| r3:source1 address, return equality |
| r4:source2 address |
| r5:byte count |
| |
| Implementation description |
| Touch in 3 lines of D-cache. |
| If source1 or source2 is unaligned copy 0-3 bytes to make source1 aligned |
| Check 2 words from src1 and src2. If unequal jump to end and |
| return src1 > src2 or src1 < src2. |
| If null check bytes before null and then jump to end and |
| return src1 > src2, src1 < src2 or src1 = src2. |
| If count = zero check bytes before zero counter and then jump to end and |
| return src1 > src2, src1 < src2 or src1 = src2. |
| If src1 = src2 and no null, repeat. */ |
| |
| EALIGN (strncmp,5,0) |
| neg r7,r3 |
| clrlwi r7,r7,20 |
| neg r8,r4 |
| clrlwi r8,r8,20 |
| srwi. r7,r7,3 |
| beq L(prebyte_count_loop) |
| srwi. r8,r8,3 |
| beq L(prebyte_count_loop) |
| cmplw r7,r8 |
| mtctr r7 |
| ble L(preword2_count_loop) |
| mtctr r8 |
| |
| L(preword2_count_loop): |
| srwi. r6,r5,3 |
| beq L(prebyte_count_loop) |
| mfctr r7 |
| cmplw r6,r7 |
| bgt L(set_count_loop) |
| mtctr r6 |
| clrlwi r5,r5,29 |
| |
| L(word2_count_loop): |
| lwz r10,0(r3) |
| lwz r6,4(r3) |
| addi r3,r3,0x08 |
| lwz r8,0(r4) |
| lwz r9,4(r4) |
| addi r4,r4,0x08 |
| dlmzb. r12,r10,r6 |
| bne L(end_check) |
| cmplw r10,r8 |
| bne L(st1) |
| cmplw r6,r9 |
| bne L(st1) |
| bdnz L(word2_count_loop) |
| |
| L(prebyte_count_loop): |
| addi r5,r5,1 |
| mtctr r5 |
| bdz L(end_strncmp) |
| |
| L(byte_count_loop): |
| lbz r6,0(r3) |
| addi r3,r3,1 |
| lbz r7,0(r4) |
| addi r4,r4,1 |
| cmplw r6,r7 |
| bne L(st1) |
| cmpwi r6,0 |
| beq L(end_strncmp) |
| bdnz L(byte_count_loop) |
| b L(end_strncmp) |
| |
| L(set_count_loop): |
| slwi r7,r7,3 |
| subf r5,r7,r5 |
| b L(word2_count_loop) |
| |
| L(end_check): |
| subfic r12,r12,4 |
| blt L(end_check2) |
| rlwinm r12,r12,3,0,31 |
| srw r10,r10,r12 |
| srw r8,r8,r12 |
| cmplw r10,r8 |
| bne L(st1) |
| b L(end_strncmp) |
| |
| L(end_check2): |
| addi r12,r12,4 |
| cmplw r10,r8 |
| rlwinm r12,r12,3,0,31 |
| bne L(st1) |
| srw r6,r6,r12 |
| srw r9,r9,r12 |
| cmplw r6,r9 |
| bne L(st1) |
| |
| L(end_strncmp): |
| addi r3,r0,0 |
| blr |
| |
| L(st1): |
| mfcr r3 |
| blr |
| END (strncmp) |
| libc_hidden_builtin_def (strncmp) |
