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Diffstat (limited to 'sysdeps/arm/armv6/strchr.S')
| -rw-r--r-- | sysdeps/arm/armv6/strchr.S | 143 |
1 files changed, 0 insertions, 143 deletions
diff --git a/sysdeps/arm/armv6/strchr.S b/sysdeps/arm/armv6/strchr.S deleted file mode 100644 index bfd0a6b237..0000000000 --- a/sysdeps/arm/armv6/strchr.S +++ /dev/null @@ -1,143 +0,0 @@ -/* strchr -- find the first instance of C in a nul-terminated string. - Copyright (C) 2013-2017 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> - - .syntax unified - .text - -ENTRY (strchr) - @ r0 = start of string - @ r1 = character to match - @ returns NULL for no match, or a pointer to the match - ldrb r2, [r0] @ load the first byte asap - uxtb r1, r1 - - @ To cater to long strings, we want to search through a few - @ characters until we reach an aligned pointer. To cater to - @ small strings, we don't want to start doing word operations - @ immediately. The compromise is a maximum of 16 bytes less - @ whatever is required to end with an aligned pointer. - @ r3 = number of characters to search in alignment loop - and r3, r0, #7 - rsb r3, r3, #15 @ 16 - 1 peeled loop iteration - cmp r2, r1 @ Found C? - it ne - cmpne r2, #0 @ Found EOS? - beq 99f - - @ Loop until we find ... -1: ldrb r2, [r0, #1]! - subs r3, r3, #1 @ ... the aligment point - it ne - cmpne r2, r1 @ ... or the character - it ne - cmpne r2, #0 @ ... or EOS - bne 1b - - @ Disambiguate the exit possibilites above - cmp r2, r1 @ Found the character - it ne - cmpne r2, #0 @ Found EOS - beq 99f - add r0, r0, #1 - - @ So now we're aligned. Now we actually need a stack frame. - push { r4, r5, r6, r7 } - cfi_adjust_cfa_offset (16) - cfi_rel_offset (r4, 0) - cfi_rel_offset (r5, 4) - cfi_rel_offset (r6, 8) - cfi_rel_offset (r7, 12) - - ldrd r2, r3, [r0], #8 - orr r1, r1, r1, lsl #8 @ Replicate C to all bytes -#ifdef ARCH_HAS_T2 - movw ip, #0x0101 - pld [r0, #64] - movt ip, #0x0101 -#else - ldr ip, =0x01010101 - pld [r0, #64] -#endif - orr r1, r1, r1, lsl #16 - - @ Loop searching for EOS or C, 8 bytes at a time. -2: - @ Subtracting (unsigned saturating) from 1 means result of 1 for - @ any byte that was originally zero and 0 otherwise. Therefore - @ we consider the lsb of each byte the "found" bit. - uqsub8 r4, ip, r2 @ Find EOS - eor r6, r2, r1 @ Convert C bytes to 0 - uqsub8 r5, ip, r3 - eor r7, r3, r1 - uqsub8 r6, ip, r6 @ Find C - pld [r0, #128] @ Prefetch 2 lines ahead - uqsub8 r7, ip, r7 - orr r4, r4, r6 @ Combine found for EOS and C - orr r5, r5, r7 - orrs r6, r4, r5 @ Combine the two words - it eq - ldrdeq r2, r3, [r0], #8 - beq 2b - - @ Found something. Disambiguate between first and second words. - @ Adjust r0 to point to the word containing the match. - @ Adjust r2 to the contents of the word containing the match. - @ Adjust r4 to the found bits for the word containing the match. - cmp r4, #0 - sub r0, r0, #4 - itte eq - moveq r4, r5 - moveq r2, r3 - subne r0, r0, #4 - - @ Find the bit-offset of the match within the word. -#if defined(__ARMEL__) - @ For LE, swap the found word so clz searches from the little end. - rev r4, r4 -#else - @ For BE, byte swap the word to make it easier to extract the byte. - rev r2, r2 -#endif - @ We're counting 0x01 (not 0x80), so the bit offset is 7 too high. - clz r3, r4 - sub r3, r3, #7 - lsr r2, r2, r3 @ Shift down found byte - uxtb r1, r1 @ Undo replication of C - uxtb r2, r2 @ Extract found byte - add r0, r0, r3, lsr #3 @ Adjust the pointer to the found byte - - pop { r4, r5, r6, r7 } - cfi_adjust_cfa_offset (-16) - cfi_restore (r4) - cfi_restore (r5) - cfi_restore (r6) - cfi_restore (r7) - - @ Disambiguate between EOS and C. -99: - cmp r2, r1 - it ne - movne r0, #0 @ Found EOS, return NULL - bx lr - -END (strchr) - -weak_alias (strchr, index) -libc_hidden_builtin_def (strchr) |