1 /* Optimized strchr implementation for PowerPC.
2 Copyright (C) 1997, 1999, 2000, 2003 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/>. */
23 /* See strlen.s for comments on how this works. */
25 /* char * [r3] strchr (const char *s [r3] , int c [r4] ) */
27 ENTRY (BP_SYM (strchr))
30 #define rRTN r3 /* outgoing result */
31 #if __BOUNDED_POINTERS__
33 # define rCHR r5 /* byte we're looking for, spread over the whole word */
34 # define rWORD r8 /* the current word */
36 # define rSTR r8 /* current word pointer */
37 # define rCHR r4 /* byte we're looking for, spread over the whole word */
38 # define rWORD r5 /* the current word */
40 #define rCLZB rCHR /* leading zero byte count */
41 #define rFEFE r6 /* constant 0xfefefeff (-0x01010101) */
42 #define r7F7F r7 /* constant 0x7f7f7f7f */
44 #define rIGN r10 /* number of bits we should ignore in the first word */
45 #define rMASK r11 /* mask with the bits to ignore set to 0 */
48 CHECK_BOUNDS_LOW (rSTR, rTMP1, rTMP2)
49 STORE_RETURN_BOUNDS (rTMP1, rTMP2)
51 rlwimi rCHR, rCHR, 8, 16, 23
53 rlwimi rCHR, rCHR, 16, 0, 15
54 rlwinm rIGN, rRTN, 3, 27, 28
58 addi rFEFE, rFEFE, -0x101
59 addi r7F7F, r7F7F, 0x7f7f
60 /* Test the first (partial?) word. */
62 srw rMASK, rMASK, rIGN
63 orc rWORD, rWORD, rMASK
64 add rTMP1, rFEFE, rWORD
65 nor rTMP2, r7F7F, rWORD
66 and. rTMP1, rTMP1, rTMP2
67 xor rTMP3, rCHR, rWORD
68 orc rTMP3, rTMP3, rMASK
73 L(loop):lwzu rWORD, 4(rSTR)
74 and. rTMP1, rTMP1, rTMP2
76 add rTMP1, rFEFE, rWORD
77 nor rTMP2, r7F7F, rWORD
79 and. rTMP1, rTMP1, rTMP2
80 /* Start test for the bytes we're looking for. */
81 xor rTMP3, rCHR, rWORD
83 add rTMP1, rFEFE, rTMP3
84 nor rTMP2, r7F7F, rTMP3
86 /* There is a zero byte in the word, but may also be a matching byte (either
87 before or after the zero byte). In fact, we may be looking for a
88 zero byte, in which case we return a match. We guess that this hasn't
91 and. rTMP1, rTMP1, rTMP2
93 STORE_RETURN_VALUE (rSTR)
95 /* It did happen. Decide which one was first...
96 I'm not sure if this is actually faster than a sequence of
97 rotates, compares, and branches (we use it anyway because it's shorter). */
98 and rFEFE, r7F7F, rWORD
99 or rMASK, r7F7F, rWORD
100 and rTMP1, r7F7F, rTMP3
101 or rIGN, r7F7F, rTMP3
102 add rFEFE, rFEFE, r7F7F
103 add rTMP1, rTMP1, r7F7F
104 nor rWORD, rMASK, rFEFE
105 nor rTMP2, rIGN, rTMP1
110 add rRTN, rSTR, rCLZB
111 CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
112 STORE_RETURN_VALUE (rSTR)
116 and rTMP1, r7F7F, rTMP3
117 or rIGN, r7F7F, rTMP3
118 add rTMP1, rTMP1, r7F7F
119 nor rTMP2, rIGN, rTMP1
123 add rRTN, rSTR, rCLZB
124 CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
125 STORE_RETURN_VALUE (rSTR)
127 END (BP_SYM (strchr))
129 weak_alias (BP_SYM (strchr), BP_SYM (index))
130 libc_hidden_builtin_def (strchr)