libecb/ecb.h

/*
 * libecb
 *
 * Copyright (©) 2009-2011 Marc Alexander Lehmann
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ECB_H
#define ECB_H

#define ECB_GCC_VERSION(major,minor) (__GNUC__ > (major) || (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))

#ifndef __cplusplus
# if __STDC_VERSION__ >= 199901L
#  define ECB_INLINE inline
typedef _Bool ecb_bool;
# else
#  define ECB_INLINE inline /* yeah! */
typedef int ecb_bool;
# endif
#endif

#define ECB_HEADER_INLINE static ECB_INLINE

#if ECB_GCC_VERSION(3,1)
# define ecb_attribute(attrlist)        __attribute__(attrlist)
# define ecb_is_constant(c)             __builtin_constant_p (c)
# define ecb_expect(expr,value)         __builtin_expect ((expr),(value))
# define ecb_prefetch(addr,rw,locality) __builtin_prefetch (addr, rw, locality)
#else
# define ecb_attribute(attrlist)
# define ecb_is_constant(c)             0
# define ecb_expect(expr,value)         (expr)
# define ecb_prefetch(addr,rw,locality)
#endif

/* no emulation for ecb_decltype */
#if ECB_GCC_VERSION(4,5)
# define ecb_decltype(x) __decltype(x)
#elif ECB_GCC_VERSION(3,0)
# define ecb_decltype(x) typeof(x)
#endif

#define ecb_noinline ecb_attribute ((noinline))
#define ecb_noreturn ecb_attribute ((noreturn))
#define ecb_unused   ecb_attribute ((unused))
#define ecb_const    ecb_attribute ((const))
#define ecb_pure     ecb_attribute ((pure))
#define ecb_hot      ecb_attribute ((hot))      /* 4.3 */
#define ecb_cold     ecb_attribute ((cold))     /* 4.3 */

#if ECB_GCC_VERSION(4,5)
# define ecb_unreachable() __builtin_unreachable ()
#else
/* this seems to work fine, but gcc always emits a warning for it :/ */
ECB_HEADER_INLINE void ecb_unreachable () ecb_attribute ((noreturn));
ECB_HEADER_INLINE void ecb_unreachable () { }
#endif

/* put into ifs if you are very sure that the expression */
/* is mostly true or mosty false. note that these return */
/* booleans, not the expression. */
#define ecb_expect_false(expr) ecb_expect ((expr) ? 1 : 0, 0)
#define ecb_expect_true(expr)  ecb_expect ((expr) ? 1 : 0, 1)

/* try to tell the compiler that some condition is definitely true */
#define ecb_assume(cond) do { if (!(cond)) unreachable (); } while (0)

/* count trailing zero bits and count # of one bits */
#if ECB_GCC_VERSION(3,4)
ECB_HEADER_INLINE int ecb_ctz32      (unsigned int x) { return __builtin_ctz      (x); }
ECB_HEADER_INLINE int ecb_popcount32 (unsigned int x) { return __builtin_popcount (x); }
#else
ECB_HEADER_INLINE
ecb_ctz32 (unsigned int x) ecb_const
{
  int r = 0;

  x &= -x; /* this isolates the lowest bit */

  if (x & 0xaaaaaaaa) r +=  1;
  if (x & 0xcccccccc) r +=  2;
  if (x & 0xf0f0f0f0) r +=  4;
  if (x & 0xff00ff00) r +=  8;
  if (x & 0xffff0000) r += 16;

  return r;
}

ECB_HEADER_INLINE
ecb_popcount32 (unsigned int x) ecb_const
{
  x -=  (x >> 1) & 0x55555555;
  x  = ((x >> 2) & 0x33333333) + (x & 0x33333333);
  x  = ((x >> 4) + x) & 0x0f0f0f0f;
  x *= 0x01010101;

  return x >> 24;
}
#endif

ECB_HEADER_INLINE unsigned char
ecb_byteorder_helper () ecb_const
{
  const uint32_t u = 0x11223344;
  return *(unsigned char *)&u;
}

ECB_HEADER_INLINE ecb_bool ecb_big_endian    () ecb_const { return ecb_byteorder_helper () == 0x11; };
ECB_HEADER_INLINE ecb_bool ecb_little_endian () ecb_const { return ecb_byteorder_helper () == 0x44; };

#if ecb_cplusplus_does_not_suck
// does not work for local types (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2657.htm)
template<typename T, int N>
static inline int array_length (const T (&arr)[N])
{
  return N;
}
#else
#define ecb_array_length(name) (sizeof (name) / sizeof (name [0]))
#endif

#endif

Revision:	1.5
Committed:	Thu May 26 17:27:15 2011 UTC (12 years, 11 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.4:	+11 -0 lines
Log Message:	* empty log message *
#	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