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Diffstat (limited to 'sysdeps/powerpc/powerpc64/power7/strchrnul.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/strchrnul.S | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc64/power7/strchrnul.S b/sysdeps/powerpc/powerpc64/power7/strchrnul.S new file mode 100644 index 0000000..fc0352c --- /dev/null +++ b/sysdeps/powerpc/powerpc64/power7/strchrnul.S @@ -0,0 +1,118 @@ +/* Optimized strchrnul implementation for PowerPC64 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] strchrnul (char *s [r3], int c [r4]) */ + .machine power7 +ENTRY (BP_SYM(__strchrnul)) + CALL_MCOUNT 2 + dcbt 0,r3 + clrrdi r8,r3,3 /* Align the address to doubleword boundary. */ + + /* Replicate byte to doubleword. */ + rlwimi r4,r4,8,16,23 + rlwimi r4,r4,16,0,15 + insrdi r4,r4,32,0 + + rlwinm r6,r3,3,26,28 /* Calculate padding. */ + ld r12,0(r8) /* Load doubleword from memory. */ + li r0,0 /* Doubleword with null chars to use + with cmpb. */ + + /* Now r4 has a doubleword of c bytes and r0 has + a doubleword of null bytes. */ + + cmpb r10,r12,r0 /* Compare each byte against c byte. */ + cmpb r9,r12,r4 /* Compare each byte against null byte. */ + + /* Move the doublewords left and right to discard the bits that are + not part of the string and to bring them back as zeros. */ + sld r10,r10,r6 + sld r9,r9,r6 + srd r10,r10,r6 + srd r9,r9,r6 + or r5,r9,r10 /* OR the results to speed things up. */ + cmpdi 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 quadword boundary? If so, skip to + the main loop. Otherwise, go through the alignment code. */ + + bt 28,L(loop) + + /* Handle DWORD2 of pair. */ + ldu r12,8(r8) + cmpb r10,r12,r0 + cmpb r9,r12,r4 + or r5,r9,r10 + cmpdi 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 doublewords, compare and merge in a + single register for speed. This is an attempt + to speed up the null-checking process for bigger strings. */ + ld r12,8(r8) + ldu r11,16(r8) + cmpb r10,r12,r0 + cmpb r9,r12,r4 + cmpb r6,r11,r0 + cmpb r7,r11,r4 + or r5,r9,r10 + or r10,r6,r7 + or r11,r5,r10 + cmpdi cr7,r11,0 + beq cr7,L(loop) + + /* OK, one (or both) of the doublewords contains a c/null byte. Check + the first doubleword and decrement the address in case the first + doubleword really contains a c/null byte. */ + + cmpdi cr6,r5,0 + addi r8,r8,-8 + bne cr6,L(done) + + /* The c/null byte must be in the second doubleword. Adjust the + address again and move the result of cmpb to r10 so we can calculate + the pointer. */ + mr r5,r10 + addi r8,r8,8 + + /* 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 + doubleword from the string. Use that to calculate the pointer. */ +L(done): + cntlzd r0,r5 /* Count leading zeros before the match. */ + srdi r0,r0,3 /* Convert leading zeros to bytes. */ + add r3,r8,r0 /* Return address of matching c/null byte. */ + blr +END (BP_SYM (__strchrnul)) +weak_alias (__strchrnul,strchrnul) +libc_hidden_builtin_def (__strchrnul) |