Mercurial > hg > octave-shane > gnulib-hg
annotate lib/integer_length_l.c @ 17282:a4996fb12971
locale: port to Solaris 2.6 and 7 + GNU gettext
* lib/locale.in.h: Just include_next <locale.h> when
being invoked recursively. This prevents problems on Solaris 2.6 and 7
when combining the localename module with GNU gettext 0.18.2.
Problem reported by Tom G. Christensen in
<http://lists.gnu.org/archive/html/bug-gnulib/2013-01/msg00084.html>.
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Thu, 10 Jan 2013 13:24:13 -0800 |
| parents | e542fd46ad6f |
| children | 344018b6e5d7 |
| rev | line source |
|---|---|
| 15954 | 1 /* integer_length_l - find most significant bit in an 'unsigned long'. |
|
17249
e542fd46ad6f
maint: update all copyright year number ranges
Eric Blake <eblake@redhat.com>
parents:
16201
diff
changeset
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2 Copyright (C) 2011-2013 Free Software Foundation, Inc. |
| 15954 | 3 |
| 4 This program is free software: you can redistribute it and/or modify | |
| 5 it under the terms of the GNU General Public License as published by | |
| 6 the Free Software Foundation; either version 3 of the License, or | |
| 7 (at your option) any later version. | |
| 8 | |
| 9 This program is distributed in the hope that it will be useful, | |
| 10 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 GNU General Public License for more details. | |
| 13 | |
| 14 You should have received a copy of the GNU General Public License | |
| 15 along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
| 16 | |
| 17 /* Written by Bruno Haible <bruno@clisp.org>, 2011. */ | |
| 18 | |
| 19 #include <config.h> | |
| 20 | |
| 21 /* Specification. */ | |
| 22 #include "integer_length.h" | |
| 23 | |
| 24 #include <limits.h> | |
| 25 #include <stddef.h> | |
| 26 | |
| 27 #undef MIN | |
| 28 #define MIN(a,b) ((a) < (b) ? (a) : (b)) | |
| 29 | |
| 30 #ifdef USE_LONG_LONG | |
| 31 # define FUNC integer_length_ll | |
| 32 # define TYPE unsigned long long | |
| 33 # define GCC_BUILTIN __builtin_clzll | |
| 34 #else | |
| 35 # define FUNC integer_length_l | |
| 36 # define TYPE unsigned long | |
| 37 # define GCC_BUILTIN __builtin_clzl | |
| 38 #endif | |
| 39 | |
| 40 #define NBITS (sizeof (TYPE) * CHAR_BIT) | |
| 41 | |
| 42 /* Modify shift count to be in bounds, even in dead code, otherwise GCC | |
| 43 emits warnings "right shift count >= width of type". */ | |
| 44 #define MSC(i) MIN (i, NBITS - 1) | |
| 45 | |
| 46 int | |
| 47 FUNC (TYPE x) | |
| 48 { | |
| 49 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) | |
| 50 if (x == 0) | |
| 51 return 0; | |
| 52 else | |
| 53 return NBITS - GCC_BUILTIN (x); | |
| 54 #else | |
| 55 /* Split x into chunks, and look at one chunk after the other. */ | |
| 56 if (sizeof (TYPE) > 2 * sizeof (unsigned int)) | |
| 57 { | |
| 58 /* Generic loop. */ | |
| 59 size_t i; | |
| 60 | |
| 61 for (i = (sizeof (TYPE) - 1) / sizeof (unsigned int); i >= 2; i--) | |
| 62 { | |
| 63 unsigned int y = x >> (i * sizeof (unsigned int) * CHAR_BIT); | |
| 64 if (y != 0) | |
| 65 return i * sizeof (unsigned int) * CHAR_BIT + integer_length (y); | |
| 66 } | |
| 67 } | |
| 68 | |
| 69 /* Unrolled the last 2 loop rounds. */ | |
| 70 /* i = 1 */ | |
| 71 if (sizeof (TYPE) > 1 * sizeof (unsigned int)) | |
| 72 { | |
| 73 unsigned int y = x >> MSC (1 * sizeof (unsigned int) * CHAR_BIT); | |
| 74 if (y != 0) | |
| 75 return 1 * sizeof (unsigned int) * CHAR_BIT + integer_length (y); | |
| 76 } | |
| 77 | |
| 78 /* i = 0 */ | |
| 79 return integer_length ((unsigned int) x); | |
| 80 #endif | |
| 81 } |