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145 lines
4.6 KiB
ArmAsm
145 lines
4.6 KiB
ArmAsm
/* Optimized strspn implementation for PowerPC64.
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Copyright (C) 2014-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* size_t [r3] strspn (const char *string [r3],
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const char *needleAccept [r4] */
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/* Performance gains are grabbed through following techniques:
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> hashing of needle.
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> hashing avoids scanning of duplicate entries in needle
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across the string.
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> unrolling when scanning for character in string
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across hash table. */
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/* Algorithm is as below:
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1. A empty hash table/dictionary is created comprising of
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256 ascii character set
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2. When hash entry is found in needle , the hash index
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is initialized to 1
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3. The string is scanned until end and for every character,
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its corresponding hash index is compared.
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4. initial length of string (count) until first hit of
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accept needle to be found is set to 0
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4. If hash index is set to 1 for the index of string,
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count is returned.
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5. Otherwise count is incremented and scanning continues
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until end of string. */
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#include <sysdep.h>
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EALIGN(strspn, 4, 0)
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CALL_MCOUNT 3
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/* PPC64 ELF ABI stack is aligned to 16 bytes. */
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addi r9,r1,-256
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/* Clear the table with 0 values */
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li r6, 0
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li r8, 4
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mtctr r8
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mr r10, r9
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.align 4
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L(zerohash):
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std r6, 0(r10)
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std r6, 8(r10)
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std r6, 16(r10)
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std r6, 24(r10)
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std r6, 32(r10)
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std r6, 40(r10)
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std r6, 48(r10)
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std r6, 56(r10)
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addi r10, r10, 64
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bdnz L(zerohash)
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lbz r10,0(r4)
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li r8, 1 /* r8=1, marker into hash if found in
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needle */
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cmpdi cr7, r10, 0 /* accept needle is NULL */
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beq cr7, L(skipHashing) /* if needle is NULL, skip hashing */
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.align 4 /* align section to 16 byte boundary */
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L(hashing):
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stbx r8, r9, r10 /* update hash with marker for the pivot of
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the needle */
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lbzu r10, 1(r4) /* load needle into r10 and update to next */
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cmpdi cr7, r10, 0 /* if needle is has reached NULL, continue */
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bne cr7, L(hashing) /* loop to hash the needle */
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L(skipHashing):
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li r10, 0 /* load counter = 0 */
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b L(beginScan)
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.align 4 /* align section to 16 byte boundary */
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L(scanUnroll):
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lbzx r8, r9, r8 /* load r8 with hash value at index */
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cmpwi cr7, r8, 0 /* if we hit marker in hash, we have found
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accept needle */
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beq cr7, L(ret1stIndex) /* we have hit accept needle, return the
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count */
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lbz r8, 1(r3) /* load string[1] into r8 */
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addi r10, r10, 4 /* increment counter */
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lbzx r8, r9, r8 /* load r8 with hash value at index */
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cmpwi cr7, r8, 0 /* if we hit marker in hash, we have found
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accept needle */
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beq cr7, L(ret2ndIndex) /* we have hit accept needle, return the
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count */
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lbz r8, 2(r3) /* load string[2] into r8 */
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lbzx r8, r9, r8 /* load r8 with hash value at index */
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cmpwi cr7, r8, 0 /* if we hit marker in hash, we have found
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accept needle */
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beq cr7, L(ret3rdIndex) /* we have hit accept needle, return the
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count */
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lbz r8, 3(r3) /* load string[3] into r8 */
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lbzx r8, r9, r8 /* load r8 with hash value at index */
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addi r3, r3, 4 /* unroll factor , increment string by 4 */
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cmpwi cr7, r8, 0 /* if we hit marker in hash, we have found
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accept needle */
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beq cr7,L(ret4thIndex) /* we have hit accept needle, return the
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count */
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L(beginScan):
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lbz r8, 0(r3) /* load string[0] into r8 */
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addi r6, r10, 1 /* place holder for counter + 1 */
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addi r5, r10, 2 /* place holder for counter + 2 */
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addi r4, r10, 3 /* place holder for counter + 3 */
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cmpdi cr7, r8, 0 /* if we hit marker in hash, we have found
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accept needle */
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bne cr7, L(scanUnroll) /* continue scanning */
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L(ret1stIndex):
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mr r3, r10 /* update r3 for return */
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blr /* return */
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L(ret2ndIndex):
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mr r3, r6 /* update r3 for return */
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blr /* return */
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L(ret3rdIndex):
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mr r3, r5 /* update r3 for return */
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blr /* return */
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L(ret4thIndex):
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mr r3, r4 /* update r3 for return */
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blr /* done */
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END(strspn)
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libc_hidden_builtin_def (strspn)
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