| 1 |
/* |
| 2 |
* libecb |
| 3 |
* |
| 4 |
* Copyright (©) 2009-2011 Marc Alexander Lehmann |
| 5 |
* All rights reserved. |
| 6 |
* |
| 7 |
* Redistribution and use in source and binary forms, with or without modifica- |
| 8 |
* tion, are permitted provided that the following conditions are met: |
| 9 |
* |
| 10 |
* 1. Redistributions of source code must retain the above copyright notice, |
| 11 |
* this list of conditions and the following disclaimer. |
| 12 |
* |
| 13 |
* 2. Redistributions in binary form must reproduce the above copyright |
| 14 |
* notice, this list of conditions and the following disclaimer in the |
| 15 |
* documentation and/or other materials provided with the distribution. |
| 16 |
* |
| 17 |
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 18 |
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
| 19 |
* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| 20 |
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
| 21 |
* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 22 |
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
| 23 |
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 24 |
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
| 25 |
* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 26 |
* OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 |
*/ |
| 28 |
|
| 29 |
#ifndef ECB_H |
| 30 |
#define ECB_H |
| 31 |
|
| 32 |
#define ECB_GCC_VERSION(major,minor) (__GNUC__ > (major) || (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor))) |
| 33 |
|
| 34 |
#if ECB_GCC_VERSION(3,1) |
| 35 |
# define ecb_attribute(attrlist) __attribute__(attrlist) |
| 36 |
# define ecb_is_constant(c) __builtin_constant_p (c) |
| 37 |
# define ecb_expect(expr,value) __builtin_expect ((expr),(value)) |
| 38 |
# define ecb_prefetch(addr,rw,locality) __builtin_prefetch (addr, rw, locality) |
| 39 |
#else |
| 40 |
# define ecb_attribute(attrlist) |
| 41 |
# define ecb_is_constant(c) 0 |
| 42 |
# define ecb_expect(expr,value) (expr) |
| 43 |
# define ecb_prefetch(addr,rw,locality) |
| 44 |
#endif |
| 45 |
|
| 46 |
/* no emulation for ecb_decltype */ |
| 47 |
#if ECB_GCC_VERSION(4,5) |
| 48 |
# define ecb_decltype(x) __decltype(x) |
| 49 |
#elif ECB_GCC_VERSION(3,0) |
| 50 |
# define ecb_decltype(x) typeof(x) |
| 51 |
#endif |
| 52 |
|
| 53 |
#define ecb_noinline ecb_attribute ((noinline)) |
| 54 |
#define ecb_noreturn ecb_attribute ((noreturn)) |
| 55 |
#define ecb_unused ecb_attribute ((unused)) |
| 56 |
#define ecb_const ecb_attribute ((const)) |
| 57 |
#define ecb_pure ecb_attribute ((pure)) |
| 58 |
#define ecb_hot ecb_attribute ((hot)) // 4.3 |
| 59 |
#define ecb_cold ecb_attribute ((cold)) // 4.3 |
| 60 |
|
| 61 |
#if ECB_GCC_VERSION(4,5) |
| 62 |
# define ecb_unreachable() __builtin_unreachable () |
| 63 |
#else |
| 64 |
// this seems to work fine, but gcc always emits a warning for it :/ |
| 65 |
static inline void ecb_unreachable () ecb_attribute ((noreturn)); |
| 66 |
static inline void ecb_unreachable () { } |
| 67 |
#endif |
| 68 |
|
| 69 |
// put into ifs if you are very sure that the expression |
| 70 |
// is mostly true or mosty false. note that these return |
| 71 |
// booleans, not the expression. |
| 72 |
#define ecb_expect_false(expr) ecb_expect ((expr) ? 1 : 0, 0) |
| 73 |
#define ecb_expect_true(expr) ecb_expect ((expr) ? 1 : 0, 1) |
| 74 |
|
| 75 |
// try to tell the compiler that some condition is definitely true |
| 76 |
#define ecb_assume(cond) do { if (!(cond)) unreachable (); } while (0) |
| 77 |
|
| 78 |
// count trailing zero bits and count # of one bits |
| 79 |
#if ECB_GCC_VERSION(3,4) |
| 80 |
static inline int ecb_ctz (unsigned int x) { return __builtin_ctz (x); } |
| 81 |
static inline int ecb_popcount (unsigned int x) { return __builtin_popcount (x); } |
| 82 |
#else |
| 83 |
static int ecb_ctz (unsigned int x) ecb_const |
| 84 |
{ |
| 85 |
int r = 0; |
| 86 |
|
| 87 |
x &= -x; // this isolates the lowest bit |
| 88 |
|
| 89 |
if (x & 0xaaaaaaaa) r += 1; |
| 90 |
if (x & 0xcccccccc) r += 2; |
| 91 |
if (x & 0xf0f0f0f0) r += 4; |
| 92 |
if (x & 0xff00ff00) r += 8; |
| 93 |
if (x & 0xffff0000) r += 16; |
| 94 |
|
| 95 |
return r; |
| 96 |
} |
| 97 |
|
| 98 |
static int ecb_popcount (unsigned int x) ecb_const |
| 99 |
{ |
| 100 |
x -= (x >> 1) & 0x55555555; |
| 101 |
x = ((x >> 2) & 0x33333333) + (x & 0x33333333); |
| 102 |
x = ((x >> 4) + x) & 0x0f0f0f0f; |
| 103 |
x *= 0x01010101; |
| 104 |
|
| 105 |
return x >> 24; |
| 106 |
} |
| 107 |
#endif |
| 108 |
|
| 109 |
#endif |
| 110 |
|
