projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| ae6b8730 RH |
1 | /* Determine the length of a string. |
| 2 | For SPARC v7. | |
| 3 | Copyright (C) 1996, 1999 Free Software Foundation, Inc. | |
| 4 | Contributed by Jakub Jelinek <jj@ultra.linux.cz>. | |
| 5 | ||
| 6 | The GNU C Library is free software; you can redistribute it and/or | |
| 7 | modify it under the terms of the GNU Library General Public License as | |
| 8 | published by the Free Software Foundation; either version 2 of the | |
| 9 | License, or (at your option) any later version. | |
| 10 | ||
| 11 | The GNU C Library is distributed in the hope that it will be useful, | |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 | Library General Public License for more details. | |
| 15 | ||
| 16 | You should have received a copy of the GNU Library General Public | |
| 17 | License along with the GNU C Library; see the file COPYING.LIB. If not, | |
| 18 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
| 19 | Boston, MA 02111-1307, USA. */ | |
| 20 | ||
| 21 | #include <sysdep.h> | |
| 22 | ||
| 23 | /* Normally, this uses ((xword - 0x01010101) & 0x80808080) test | |
| 24 | to find out if any byte in xword could be zero. This is fast, but | |
| 25 | also gives false alarm for any byte in range 0x81-0xff. It does | |
| 26 | not matter for correctness, as if this test tells us there could | |
| 27 | be some zero byte, we check it byte by byte, but if bytes with | |
| 28 | high bits set are common in the strings, then this will give poor | |
| 29 | performance. You can #define EIGHTBIT_NOT_RARE and the algorithm | |
| 30 | will use one tick slower, but more precise test | |
| 31 | ((xword - 0x01010101) & (~xword) & 0x80808080), | |
| 32 | which does not give any false alarms (but if some bits are set, | |
| 33 | one cannot assume from it which bytes are zero and which are not). | |
| 34 | It is yet to be measured, what is the correct default for glibc | |
| 35 | in these days for an average user. | |
| 36 | */ | |
| 37 | ||
| 38 | .text | |
| 39 | .align 4 | |
| 40 | 10: ldub [%o0], %o5 | |
| 41 | cmp %o5, 0 | |
| 42 | be 1f | |
| 43 | add %o0, 1, %o0 | |
| 44 | andcc %o0, 3, %g0 | |
| 45 | be 4f | |
| 46 | or %o4, %lo(0x80808080), %o3 | |
| 47 | ldub [%o0], %o5 | |
| 48 | cmp %o5, 0 | |
| 49 | be 2f | |
| 50 | add %o0, 1, %o0 | |
| 51 | andcc %o0, 3, %g0 | |
| 52 | be 5f | |
| 53 | sethi %hi(0x01010101), %o4 | |
| 54 | ldub [%o0], %o5 | |
| 55 | cmp %o5, 0 | |
| 56 | be 3f | |
| 57 | add %o0, 1, %o0 | |
| 58 | b 11f | |
| 59 | or %o4, %lo(0x01010101), %o2 | |
| 60 | 1: retl | |
| 61 | mov 0, %o0 | |
| 62 | 2: retl | |
| 63 | mov 1, %o0 | |
| 64 | 3: retl | |
| 65 | mov 2, %o0 | |
| 66 | ||
| 67 | ENTRY(strlen) | |
| 68 | mov %o0, %o1 | |
| 69 | andcc %o0, 3, %g0 | |
| 70 | bne 10b | |
| 71 | sethi %hi(0x80808080), %o4 | |
| 72 | or %o4, %lo(0x80808080), %o3 | |
| 73 | 4: sethi %hi(0x01010101), %o4 | |
| 74 | 5: or %o4, %lo(0x01010101), %o2 | |
| 75 | 11: ld [%o0], %o5 | |
| 76 | 12: sub %o5, %o2, %o4 | |
| 77 | #ifdef EIGHTBIT_NOT_RARE | |
| 78 | andn %o4, %o5, %o4 | |
| 79 | #endif | |
| 80 | andcc %o4, %o3, %g0 | |
| 81 | be 11b | |
| 82 | add %o0, 4, %o0 | |
| 83 | ||
| 84 | srl %o5, 24, %g5 | |
| 85 | andcc %g5, 0xff, %g0 | |
| 86 | be 13f | |
| 87 | add %o0, -4, %o4 | |
| 88 | srl %o5, 16, %g5 | |
| 89 | andcc %g5, 0xff, %g0 | |
| 90 | be 13f | |
| 91 | add %o4, 1, %o4 | |
| 92 | srl %o5, 8, %g5 | |
| 93 | andcc %g5, 0xff, %g0 | |
| 94 | be 13f | |
| 95 | add %o4, 1, %o4 | |
| 96 | andcc %o5, 0xff, %g0 | |
| 97 | bne,a 12b | |
| 98 | ld [%o0], %o5 | |
| 99 | add %o4, 1, %o4 | |
| 100 | 13: retl | |
| 101 | sub %o4, %o1, %o0 | |
| 102 | END(strlen) |