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Revision: 1.5
Committed: Thu May 26 17:27:15 2011 UTC (13 years ago) by root
Content type: text/plain
Branch: MAIN
Changes since 1.4: +11 -0 lines
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# User Rev Content
1 root 1.1 /*
2     * libecb
3     *
4 root 1.2 * Copyright (©) 2009-2011 Marc Alexander Lehmann
5 root 1.1 * 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 root 1.4 #ifndef __cplusplus
35     # if __STDC_VERSION__ >= 199901L
36     # define ECB_INLINE inline
37     typedef _Bool ecb_bool;
38     # else
39     # define ECB_INLINE inline /* yeah! */
40     typedef int ecb_bool;
41     # endif
42     #endif
43    
44     #define ECB_HEADER_INLINE static ECB_INLINE
45 root 1.3
46 root 1.1 #if ECB_GCC_VERSION(3,1)
47     # define ecb_attribute(attrlist) __attribute__(attrlist)
48     # define ecb_is_constant(c) __builtin_constant_p (c)
49     # define ecb_expect(expr,value) __builtin_expect ((expr),(value))
50     # define ecb_prefetch(addr,rw,locality) __builtin_prefetch (addr, rw, locality)
51     #else
52     # define ecb_attribute(attrlist)
53     # define ecb_is_constant(c) 0
54     # define ecb_expect(expr,value) (expr)
55     # define ecb_prefetch(addr,rw,locality)
56     #endif
57    
58 root 1.2 /* no emulation for ecb_decltype */
59 root 1.1 #if ECB_GCC_VERSION(4,5)
60     # define ecb_decltype(x) __decltype(x)
61     #elif ECB_GCC_VERSION(3,0)
62     # define ecb_decltype(x) typeof(x)
63     #endif
64    
65     #define ecb_noinline ecb_attribute ((noinline))
66     #define ecb_noreturn ecb_attribute ((noreturn))
67     #define ecb_unused ecb_attribute ((unused))
68     #define ecb_const ecb_attribute ((const))
69     #define ecb_pure ecb_attribute ((pure))
70 root 1.4 #define ecb_hot ecb_attribute ((hot)) /* 4.3 */
71     #define ecb_cold ecb_attribute ((cold)) /* 4.3 */
72 root 1.1
73     #if ECB_GCC_VERSION(4,5)
74     # define ecb_unreachable() __builtin_unreachable ()
75     #else
76 root 1.4 /* this seems to work fine, but gcc always emits a warning for it :/ */
77     ECB_HEADER_INLINE void ecb_unreachable () ecb_attribute ((noreturn));
78     ECB_HEADER_INLINE void ecb_unreachable () { }
79 root 1.1 #endif
80    
81 root 1.3 /* put into ifs if you are very sure that the expression */
82     /* is mostly true or mosty false. note that these return */
83     /* booleans, not the expression. */
84 root 1.1 #define ecb_expect_false(expr) ecb_expect ((expr) ? 1 : 0, 0)
85     #define ecb_expect_true(expr) ecb_expect ((expr) ? 1 : 0, 1)
86    
87 root 1.3 /* try to tell the compiler that some condition is definitely true */
88 root 1.1 #define ecb_assume(cond) do { if (!(cond)) unreachable (); } while (0)
89    
90 root 1.3 /* count trailing zero bits and count # of one bits */
91 root 1.1 #if ECB_GCC_VERSION(3,4)
92 root 1.4 ECB_HEADER_INLINE int ecb_ctz32 (unsigned int x) { return __builtin_ctz (x); }
93     ECB_HEADER_INLINE int ecb_popcount32 (unsigned int x) { return __builtin_popcount (x); }
94 root 1.1 #else
95 root 1.3 ECB_HEADER_INLINE
96 root 1.4 ecb_ctz32 (unsigned int x) ecb_const
97 root 1.1 {
98     int r = 0;
99    
100 root 1.4 x &= -x; /* this isolates the lowest bit */
101 root 1.1
102     if (x & 0xaaaaaaaa) r += 1;
103     if (x & 0xcccccccc) r += 2;
104     if (x & 0xf0f0f0f0) r += 4;
105     if (x & 0xff00ff00) r += 8;
106     if (x & 0xffff0000) r += 16;
107    
108     return r;
109     }
110    
111 root 1.3 ECB_HEADER_INLINE
112 root 1.4 ecb_popcount32 (unsigned int x) ecb_const
113 root 1.1 {
114     x -= (x >> 1) & 0x55555555;
115     x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
116     x = ((x >> 4) + x) & 0x0f0f0f0f;
117     x *= 0x01010101;
118    
119     return x >> 24;
120     }
121     #endif
122    
123 root 1.3 ECB_HEADER_INLINE unsigned char
124     ecb_byteorder_helper () ecb_const
125     {
126     const uint32_t u = 0x11223344;
127     return *(unsigned char *)&u;
128     }
129    
130 root 1.4 ECB_HEADER_INLINE ecb_bool ecb_big_endian () ecb_const { return ecb_byteorder_helper () == 0x11; };
131     ECB_HEADER_INLINE ecb_bool ecb_little_endian () ecb_const { return ecb_byteorder_helper () == 0x44; };
132 root 1.3
133 root 1.5 #if ecb_cplusplus_does_not_suck
134     // does not work for local types (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2657.htm)
135     template<typename T, int N>
136     static inline int array_length (const T (&arr)[N])
137     {
138     return N;
139     }
140     #else
141     #define ecb_array_length(name) (sizeof (name) / sizeof (name [0]))
142     #endif
143    
144 root 1.1 #endif
145