diff options
Diffstat (limited to 'sysdeps/powerpc/powerpc32/power7/rawmemchr.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc32/power7/rawmemchr.S | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc32/power7/rawmemchr.S b/sysdeps/powerpc/powerpc32/power7/rawmemchr.S new file mode 100644 index 0000000000..09bc1c24b2 --- /dev/null +++ b/sysdeps/powerpc/powerpc32/power7/rawmemchr.S @@ -0,0 +1,102 @@ +/* Optimized rawmemchr implementation for PowerPC32/POWER7 using cmpb insn. + 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] rawmemchr (void *s [r3], int c [r4]) */ + .machine power7 +ENTRY (BP_SYM(__rawmemchr)) + CALL_MCOUNT + dcbt 0,r3 + clrrwi r8,r3,2 /* Align the address to word boundary. */ + + /* Replicate byte to word. */ + rlwimi r4,r4,8,16,23 + rlwimi r4,r4,16,0,15 + + /* Now r4 has a word of c bytes. */ + + rlwinm r6,r3,3,27,28 /* Calculate padding. */ + lwz r12,0(r8) /* Load word from memory. */ + cmpb r5,r12,r4 /* Compare each byte against c byte. */ + slw r5,r5,r6 /* Move left to discard ignored bits. */ + srw r5,r5,r6 /* Bring the bits back as zeros. */ + cmpwi cr7,r5,0 /* If r5 == 0, no c 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 r5,r12,r4 + 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. */ + + /* 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): + /* Load two words, compare and merge in a + single register for speed. This is an attempt + to speed up the byte-checking process for bigger strings. */ + lwz r12,4(r8) + lwzu r11,8(r8) + cmpb r5,r12,r4 + cmpb r6,r11,r4 + or r7,r5,r6 + cmpwi cr7,r7,0 + beq cr7,L(loop) + + /* OK, one (or both) of the words contains a 'c' byte. Check + the first word and decrement the address in case the first + word really contains a c byte. */ + + cmpwi cr6,r5,0 + addi r8,r8,-4 + bne cr6,L(done) + + /* The 'c' 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,r6 + addi r8,r8,4 + + /* r5 has the output of the cmpb instruction, that is, it contains + 0xff in the same position as the 'c' byte in the original + word from the string. Use that fact to find out what is + the position of the byte inside the string. */ +L(done): + cntlzw r0,r5 /* Count leading zeros before the match. */ + srwi r0,r0,3 /* Convert leading zeroes to bytes. */ + add r3,r8,r0 /* Return address of the matching char. */ + blr +END (BP_SYM (__rawmemchr)) +weak_alias (__rawmemchr,rawmemchr) +libc_hidden_builtin_def (__rawmemchr) |