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Diffstat (limited to 'REORG.TODO/sysdeps/powerpc/powerpc32/power7/strnlen.S')
| -rw-r--r-- | REORG.TODO/sysdeps/powerpc/powerpc32/power7/strnlen.S | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/powerpc/powerpc32/power7/strnlen.S b/REORG.TODO/sysdeps/powerpc/powerpc32/power7/strnlen.S new file mode 100644 index 0000000000..6019d5be5b --- /dev/null +++ b/REORG.TODO/sysdeps/powerpc/powerpc32/power7/strnlen.S @@ -0,0 +1,176 @@ +/* Optimized strnlen implementation for PowerPC32/POWER7 using cmpb insn. + Copyright (C) 2010-2017 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, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + +/* int [r3] strnlen (char *s [r3], int size [r4]) */ + .machine power7 +ENTRY (__strnlen) + CALL_MCOUNT + dcbt 0,r3 + clrrwi r8,r3,2 /* Align the address to word boundary. */ + add r7,r3,r4 /* Calculate the last acceptable address. */ + cmplwi r4,16 + li r0,0 /* Word with null chars. */ + addi r7,r7,-1 + ble L(small_range) + + rlwinm r6,r3,3,27,28 /* Calculate padding. */ + lwz r12,0(r8) /* Load word from memory. */ + cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */ +#ifdef __LITTLE_ENDIAN__ + srw r10,r10,r6 + slw r10,r10,r6 +#else + slw r10,r10,r6 + srw r10,r10,r6 +#endif + cmplwi cr7,r10,0 /* If r10 == 0, no null's have been found. */ + bne cr7,L(done) + + clrrwi r7,r7,2 /* Address of last word. */ + 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_setup) + + /* Handle WORD2 of pair. */ + lwzu r12,4(r8) + cmpb r10,r12,r0 + cmplwi cr7,r10,0 + bne cr7,L(done) + +L(loop_setup): + /* The last word we want to read in the loop below is the one + containing the last byte of the string, ie. the word at + (s + size - 1) & ~3, or r7. The first word read is at + r8 + 4, we read 2 * cnt words, so the last word read will + be at r8 + 4 + 8 * cnt - 4. Solving for cnt gives + cnt = (r7 - r8) / 8 */ + sub r5,r7,r8 + srwi r6,r5,3 /* Number of loop iterations. */ + mtctr r6 /* Setup the counter. */ + + /* Main loop to look for the null byte in 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 null-checking process for bigger strings. */ + + lwz r12,4(r8) + lwzu r11,8(r8) + cmpb r10,r12,r0 + cmpb r9,r11,r0 + or r5,r9,r10 /* Merge everything in one word. */ + cmplwi cr7,r5,0 + bne cr7,L(found) + bdnz L(loop) + + /* We may have one more word to read. */ + cmplw cr6,r8,r7 + beq cr6,L(end_max) + + lwzu r12,4(r8) + cmpb r10,r12,r0 + cmplwi cr6,r10,0 + bne cr6,L(done) + +L(end_max): + mr r3,r4 + blr + + /* 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. */ + .align 4 +L(found): + cmplwi cr6,r10,0 + addi r8,r8,-4 + bne cr6,L(done) + + /* 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 + length. */ + + mr r10,r9 + addi r8,r8,4 + + /* r10 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 length. + We need to make sure the null char is *before* the end of the + range. */ +L(done): +#ifdef __LITTLE_ENDIAN__ + addi r0,r10,-1 + andc r0,r0,r10 + popcntw r0,r0 +#else + cntlzw r0,r10 /* Count leading zeros before the match. */ +#endif + sub r3,r8,r3 + srwi r0,r0,3 /* Convert leading/trailing zeros to bytes. */ + add r3,r3,r0 /* Length until the match. */ + cmplw r3,r4 + blelr + mr r3,r4 + blr + +/* Deals with size <= 16. */ + .align 4 +L(small_range): + cmplwi r4,0 + beq L(end_max) + + clrrwi r7,r7,2 /* Address of last word. */ + + rlwinm r6,r3,3,27,28 /* Calculate padding. */ + lwz r12,0(r8) /* Load word from memory. */ + cmpb r10,r12,r0 /* Check for null bytes in WORD1. */ +#ifdef __LITTLE_ENDIAN__ + srw r10,r10,r6 + slw r10,r10,r6 +#else + slw r10,r10,r6 + srw r10,r10,r6 +#endif + cmplwi cr7,r10,0 + bne cr7,L(done) + + cmplw r8,r7 + beq L(end_max) + + .p2align 5 +L(loop_small): + lwzu r12,4(r8) + cmpb r10,r12,r0 + cmplwi cr6,r10,0 + bne cr6,L(done) + cmplw r8,r7 + bne L(loop_small) + mr r3,r4 + blr + +END (__strnlen) +libc_hidden_def (__strnlen) +weak_alias (__strnlen, strnlen) +libc_hidden_builtin_def (strnlen) |