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Diffstat (limited to 'sysdeps/powerpc/powerpc32/power7/strchr.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc32/power7/strchr.S | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc32/power7/strchr.S b/sysdeps/powerpc/powerpc32/power7/strchr.S new file mode 100644 index 0000000..55b754f --- /dev/null +++ b/sysdeps/powerpc/powerpc32/power7/strchr.S @@ -0,0 +1,203 @@ +/* Optimized strchr implementation for PowerPC32 using cmpb. + Copyright (C) 2010 Free Software Foundation, Inc. + Contributed by Luis Machado <luisgpm@br.ibm.com>. + 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, write to the Free + Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA + 02110-1301 USA. */ + +#include <sysdep.h> +#include <bp-sym.h> +#include <bp-asm.h> + +/* int [r3] strchr (char *s [r3], int c [r4]) */ + .machine power7 +ENTRY (BP_SYM(strchr)) + CALL_MCOUNT + dcbt 0,r3 + clrrwi r8,r3,2 /* Align the address to word boundary. */ + cmpwi cr7,r4,0 + lwz r12,0(r8) /* Load word from memory. */ + li r0,0 /* Word with null chars to use + with cmpb. */ + + rlwinm r6,r3,3,27,28 /* Calculate padding. */ + + beq cr7,L(null_match) + + /* Replicate byte to word. */ + rlwimi r4,r4,8,16,23 + rlwimi r4,r4,16,0,15 + + /* Now r4 has a word of c bytes and r0 has + a word of null bytes. */ + + cmpb r10,r12,r4 /* Compare each byte against c byte. */ + cmpb r11,r12,r0 /* Compare each byte against null byte. */ + + /* Move the words left and right to discard the bits that are + not part of the string and to bring them back as zeros. */ + + slw r10,r10,r6 + slw r11,r11,r6 + srw r10,r10,r6 + srw r11,r11,r6 + or r5,r10,r11 /* OR the results to speed things up. */ + cmpwi cr7,r5,0 /* If r5 == 0, no c or null bytes + have been found. */ + bne cr7,L(done) + + mtcrf 0x01,r8 + + /* Are we now aligned to a doubleword boundary? If so, skip to + the main loop. Otherwise, go through the alignment code. */ + + bt 29,L(loop) + + /* Handle WORD2 of pair. */ + lwzu r12,4(r8) + cmpb r10,r12,r4 + cmpb r11,r12,r0 + or r5,r10,r11 + cmpwi cr7,r5,0 + bne cr7,L(done) + b L(loop) /* We branch here (rather than falling through) + to skip the nops due to heavy alignment + of the loop below. */ + + .p2align 5 +L(loop): + /* Load two words, compare and merge in a + single register for speed. This is an attempt + to speed up the null-checking process for bigger strings. */ + lwz r12,4(r8) + lwzu r9,8(r8) + cmpb r10,r12,r4 + cmpb r11,r12,r0 + cmpb r6,r9,r4 + cmpb r7,r9,r0 + or r12,r10,r11 + or r9,r6,r7 + or r5,r12,r9 + cmpwi cr7,r5,0 + beq cr7,L(loop) + + /* OK, one (or both) of the words contains a c/null byte. Check + the first word and decrement the address in case the first + word really contains a c/null byte. */ + + cmpwi cr6,r12,0 + addi r8,r8,-4 + bne cr6,L(done) + + /* The c/null byte must be in the second word. Adjust the address + again and move the result of cmpb to r10 so we can calculate the + pointer. */ + + mr r10,r6 + mr r11,r7 + addi r8,r8,4 + + /* r5 has the output of the cmpb instruction, that is, it contains + 0xff in the same position as the c/null byte in the original + word from the string. Use that to calculate the pointer. */ +L(done): + cntlzw r4,r10 /* Count leading zeroes before c matches. */ + cntlzw r0,r11 /* Count leading zeroes before null matches. */ + cmplw cr7,r4,r0 + bgt cr7,L(no_match) + srwi r0,r4,3 /* Convert leading zeroes to bytes. */ + add r3,r8,r0 /* Return address of the matching c byte + or null in case c was not found. */ + blr + + .align 4 +L(no_match): + li r3,0 + blr + +/* We are here because strchr was called with a null byte. */ + .align 4 +L(null_match): + /* r0 has a word of null bytes. */ + + cmpb r5,r12,r0 /* Compare each byte against null bytes. */ + + /* Move the words left and right to discard the bits that are + not part of the string and to bring them back as zeros. */ + + slw r5,r5,r6 + srw r5,r5,r6 + cmpwi cr7,r5,0 /* If r10 == 0, no c or null bytes + have been found. */ + bne cr7,L(done_null) + + mtcrf 0x01,r8 + + /* Are we now aligned to a doubleword boundary? If so, skip to + the main loop. Otherwise, go through the alignment code. */ + + bt 29,L(loop_null) + + /* Handle WORD2 of pair. */ + lwzu r12,4(r8) + cmpb r5,r12,r0 + cmpwi cr7,r5,0 + bne cr7,L(done_null) + b L(loop_null) /* We branch here (rather than falling through) + to skip the nops due to heavy alignment + of the loop below. */ + + /* Main loop to look for the end of the string. Since it's a + small loop (< 8 instructions), align it to 32-bytes. */ + .p2align 5 +L(loop_null): + /* Load two words, compare and merge in a + single register for speed. This is an attempt + to speed up the null-checking process for bigger strings. */ + lwz r12,4(r8) + lwzu r11,8(r8) + cmpb r5,r12,r0 + cmpb r10,r11,r0 + or r6,r5,r10 + cmpwi cr7,r6,0 + beq cr7,L(loop_null) + + /* OK, one (or both) of the words contains a null byte. Check + the first word and decrement the address in case the first + word really contains a null byte. */ + + cmpwi cr6,r5,0 + addi r8,r8,-4 + bne cr6,L(done_null) + + /* The null byte must be in the second word. Adjust the address + again and move the result of cmpb to r10 so we can calculate the + pointer. */ + + mr r5,r10 + addi r8,r8,4 + + /* r5 has the output of the cmpb instruction, that is, it contains + 0xff in the same position as the null byte in the original + word from the string. Use that to calculate the pointer. */ +L(done_null): + cntlzw r0,r5 /* Count leading zeros before the match. */ + srwi r0,r0,3 /* Convert leading zeros to bytes. */ + add r3,r8,r0 /* Return address of the matching null byte. */ + blr +END (BP_SYM (strchr)) +weak_alias (BP_SYM (strchr), BP_SYM (index)) +libc_hidden_builtin_def (strchr) |