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

#include <inttypes.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_unlikely(expr) ecb_expect ((expr) ? 1 : 0, 0)
#define ecb_likely(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      (uint32_t x) { return __builtin_ctz      (x); }
ECB_HEADER_INLINE int ecb_popcount32 (uint32_t x) { return __builtin_popcount (x); }
#else
ECB_HEADER_INLINE
ecb_ctz32 (uint32_t 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 (uint32_t 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

ECB_INLINE uint32_t
ecb_rotate32_right (uint32_t c, unsigned int count = 1)
{
  return (c << (32 - count)) | (c >> count);
}

ECB_INLINE uint32_t
ecb_rotate32_left (uint32_t c, unsigned int count = 1)
{
  return (c >> (32 - count)) | (c << count);
}

#endif

Revision:	1.6
Committed:	Thu May 26 17:35:47 2011 UTC (13 years ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.5:	+20 -6 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	root	1.6	#include <inttypes.h>
33
34	root	1.1	#define ECB_GCC_VERSION(major,minor) (__GNUC__ > (major) \|\| (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))
35
36	root	1.4	#ifndef __cplusplus
37			# if __STDC_VERSION__ >= 199901L
38			# define ECB_INLINE inline
39			typedef _Bool ecb_bool;
40			# else
41			# define ECB_INLINE inline /* yeah! */
42			typedef int ecb_bool;
43			# endif
44			#endif
45
46			#define ECB_HEADER_INLINE static ECB_INLINE
47	root	1.3
48	root	1.1	#if ECB_GCC_VERSION(3,1)
49			# define ecb_attribute(attrlist) __attribute__(attrlist)
50			# define ecb_is_constant(c) __builtin_constant_p (c)
51			# define ecb_expect(expr,value) __builtin_expect ((expr),(value))
52			# define ecb_prefetch(addr,rw,locality) __builtin_prefetch (addr, rw, locality)
53			#else
54			# define ecb_attribute(attrlist)
55			# define ecb_is_constant(c) 0
56			# define ecb_expect(expr,value) (expr)
57			# define ecb_prefetch(addr,rw,locality)
58			#endif
59
60	root	1.2	/* no emulation for ecb_decltype */
61	root	1.1	#if ECB_GCC_VERSION(4,5)
62			# define ecb_decltype(x) __decltype(x)
63			#elif ECB_GCC_VERSION(3,0)
64			# define ecb_decltype(x) typeof(x)
65			#endif
66
67			#define ecb_noinline ecb_attribute ((noinline))
68			#define ecb_noreturn ecb_attribute ((noreturn))
69			#define ecb_unused ecb_attribute ((unused))
70			#define ecb_const ecb_attribute ((const))
71			#define ecb_pure ecb_attribute ((pure))
72	root	1.4	#define ecb_hot ecb_attribute ((hot)) /* 4.3 */
73			#define ecb_cold ecb_attribute ((cold)) /* 4.3 */
74	root	1.1
75			#if ECB_GCC_VERSION(4,5)
76			# define ecb_unreachable() __builtin_unreachable ()
77			#else
78	root	1.4	/* this seems to work fine, but gcc always emits a warning for it :/ */
79			ECB_HEADER_INLINE void ecb_unreachable () ecb_attribute ((noreturn));
80			ECB_HEADER_INLINE void ecb_unreachable () { }
81	root	1.1	#endif
82
83	root	1.3	/* put into ifs if you are very sure that the expression */
84			/* is mostly true or mosty false. note that these return */
85			/* booleans, not the expression. */
86	root	1.6	#define ecb_unlikely(expr) ecb_expect ((expr) ? 1 : 0, 0)
87			#define ecb_likely(expr) ecb_expect ((expr) ? 1 : 0, 1)
88	root	1.1
89	root	1.3	/* try to tell the compiler that some condition is definitely true */
90	root	1.1	#define ecb_assume(cond) do { if (!(cond)) unreachable (); } while (0)
91
92	root	1.3	/* count trailing zero bits and count # of one bits */
93	root	1.1	#if ECB_GCC_VERSION(3,4)
94	root	1.6	ECB_HEADER_INLINE int ecb_ctz32 (uint32_t x) { return __builtin_ctz (x); }
95			ECB_HEADER_INLINE int ecb_popcount32 (uint32_t x) { return __builtin_popcount (x); }
96	root	1.1	#else
97	root	1.3	ECB_HEADER_INLINE
98	root	1.6	ecb_ctz32 (uint32_t x) ecb_const
99	root	1.1	{
100			int r = 0;
101
102	root	1.4	x &= -x; /* this isolates the lowest bit */
103	root	1.1
104			if (x & 0xaaaaaaaa) r += 1;
105			if (x & 0xcccccccc) r += 2;
106			if (x & 0xf0f0f0f0) r += 4;
107			if (x & 0xff00ff00) r += 8;
108			if (x & 0xffff0000) r += 16;
109
110			return r;
111			}
112
113	root	1.3	ECB_HEADER_INLINE
114	root	1.6	ecb_popcount32 (uint32_t x) ecb_const
115	root	1.1	{
116			x -= (x >> 1) & 0x55555555;
117			x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
118			x = ((x >> 4) + x) & 0x0f0f0f0f;
119			x *= 0x01010101;
120
121			return x >> 24;
122			}
123			#endif
124
125	root	1.3	ECB_HEADER_INLINE unsigned char
126			ecb_byteorder_helper () ecb_const
127			{
128			const uint32_t u = 0x11223344;
129			return (unsigned char )&u;
130			}
131
132	root	1.4	ECB_HEADER_INLINE ecb_bool ecb_big_endian () ecb_const { return ecb_byteorder_helper () == 0x11; };
133			ECB_HEADER_INLINE ecb_bool ecb_little_endian () ecb_const { return ecb_byteorder_helper () == 0x44; };
134	root	1.3
135	root	1.5	#if ecb_cplusplus_does_not_suck
136			// does not work for local types (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2657.htm)
137			template<typename T, int N>
138			static inline int array_length (const T (&arr)[N])
139			{
140			return N;
141			}
142			#else
143			#define ecb_array_length(name) (sizeof (name) / sizeof (name [0]))
144			#endif
145
146	root	1.6	ECB_INLINE uint32_t
147			ecb_rotate32_right (uint32_t c, unsigned int count = 1)
148			{
149			return (c << (32 - count)) \| (c >> count);
150			}
151
152			ECB_INLINE uint32_t
153			ecb_rotate32_left (uint32_t c, unsigned int count = 1)
154			{
155			return (c >> (32 - count)) \| (c << count);
156			}
157
158	root	1.1	#endif
159