1 /* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
2 Copyright (C) 2014-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
21 /* int [r3] strrchr (char *s [r3], int c [r4]) */
26 clrrdi r8,r3,3 /* Align the address to doubleword boundary. */
28 ld r12,0(r8) /* Load doubleword from memory. */
29 li r9,0 /* used to store last occurence */
30 li r0,0 /* Doubleword with null chars to use
33 rlwinm r6,r3,3,26,28 /* Calculate padding. */
37 /* Replicate byte to doubleword. */
42 /* r4 is changed now ,if its passed as more chars
43 check for null again */
46 /* Now r4 has a doubleword of c bytes and r0 has
47 a doubleword of null bytes. */
49 cmpb r10,r12,r4 /* Compare each byte against c byte. */
50 cmpb r11,r12,r0 /* Compare each byte against null byte. */
52 /* Move the doublewords left and right to discard the bits that are
53 not part of the string and bring them back as zeros. */
54 #ifdef __LITTLE_ENDIAN__
65 or r5,r10,r11 /* OR the results to speed things up. */
66 cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
73 /* Are we now aligned to a doubleword boundary? If so, skip to
74 the main loop. Otherwise, go through the alignment code. */
78 /* Handle WORD2 of pair. */
85 b L(loop) /* We branch here (rather than falling through)
86 to skip the nops due to heavy alignment
90 /* Load two doublewords, compare and merge in a
91 single register for speed. This is an attempt
92 to speed up the null-checking process for bigger strings. */
105 /* OK, one (or both) of the doublewords contains a c/null byte. Check
106 the first doubleword and decrement the address in case the first
107 doubleword really contains a c/null byte. */
112 /* The c/null byte must be in the second doubleword. Adjust the
113 address again and move the result of cmpb to r10 so we can calculate
120 /* r10/r11 have the output of the cmpb instructions, that is,
121 0xff in the same position as the c/null byte in the original
122 doubleword from the string. Use that to calculate the pointer. */
125 /* if there are more than one 0xff in r11, find the first pos of ff
126 in r11 and fill r10 with 0 from that position */
129 #ifdef __LITTLE_ENDIAN__
138 #ifdef __LITTLE_ENDIAN__
145 #ifdef __LITTLE_ENDIAN__
146 cntlzd r0,r10 /* Count leading zeros before c matches. */
154 addi r3,r10,-1 /* Count trailing zeros before c matches. */
160 srdi r0,r0,3 /* Convert trailing zeros to bytes. */
162 add r9,r8,r0 /* Return address of the matching c byte
163 or null in case c was not found. */
165 cmpdi cr7,r11,0 /* If r11 == 0, no null's have been found. */
173 /* We are here because strrchr was called with a null byte. */
176 /* r0 has a doubleword of null bytes. */
178 cmpb r5,r12,r0 /* Compare each byte against null bytes. */
180 /* Move the doublewords left and right to discard the bits that are
181 not part of the string and bring them back as zeros. */
182 #ifdef __LITTLE_ENDIAN__
189 cmpdi cr7,r5,0 /* If r10 == 0, no c or null bytes
195 /* Are we now aligned to a quadword boundary? If so, skip to
196 the main loop. Otherwise, go through the alignment code. */
200 /* Handle WORD2 of pair. */
205 b L(loop_null) /* We branch here (rather than falling through)
206 to skip the nops due to heavy alignment
207 of the loop below. */
209 /* Main loop to look for the end of the string. Since it's a
210 small loop (< 8 instructions), align it to 32-bytes. */
213 /* Load two doublewords, compare and merge in a
214 single register for speed. This is an attempt
215 to speed up the null-checking process for bigger strings. */
224 /* OK, one (or both) of the doublewords contains a null byte. Check
225 the first doubleword and decrement the address in case the first
226 doubleword really contains a null byte. */
232 /* The null byte must be in the second doubleword. Adjust the address
233 again and move the result of cmpb to r10 so we can calculate the
239 /* r5 has the output of the cmpb instruction, that is, it contains
240 0xff in the same position as the null byte in the original
241 doubleword from the string. Use that to calculate the pointer. */
243 #ifdef __LITTLE_ENDIAN__
248 cntlzd r0,r5 /* Count leading zeros before the match. */
250 srdi r0,r0,3 /* Convert trailing zeros to bytes. */
251 add r3,r8,r0 /* Return address of the matching null byte. */
254 weak_alias (strrchr, rindex)
255 libc_hidden_builtin_def (strrchr)