FFmpeg: libavutil/intmath.h Source File

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libavutil

intmath.h

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1 /*

3 *

4 * This file is part of FFmpeg.

5 *

6 * FFmpeg is free software; you can redistribute it and/or

7 * modify it under the terms of the GNU Lesser General Public

8 * License as published by the Free Software Foundation; either

9 * version 2.1 of the License, or (at your option) any later version.

10 *

11 * FFmpeg is distributed in the hope that it will be useful,

12 * but WITHOUT ANY WARRANTY; without even the implied warranty of

13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

14 * Lesser General Public License for more details.

15 *

16 * You should have received a copy of the GNU Lesser General Public

17 * License along with FFmpeg; if not, write to the Free Software

18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

19 */

21 #ifndef AVUTIL_INTMATH_H

22 #define AVUTIL_INTMATH_H

24 #include <stdint.h>

26 #include "config.h"

27 #include "attributes.h"

29 #if ARCH_ARM

30 # include "arm/intmath.h"

31 #endif

32 #if ARCH_X86

33 # include "x86/intmath.h"

34 #endif

36 /**

37 * @addtogroup lavu_internal

38 * @{

39 */

41 #if HAVE_FAST_CLZ

42 #if AV_GCC_VERSION_AT_LEAST(3,4)

43 #ifndef ff_log2

44 # define ff_log2(x) (31 - __builtin_clz((x)|1))

45 # ifndef ff_log2_16bit

46 # define ff_log2_16bit av_log2

47 # endif

48 #endif /* ff_log2 */

49 #elif defined( __INTEL_COMPILER )

50 #ifndef ff_log2

51 # define ff_log2(x) (_bit_scan_reverse((x)|1))

52 # ifndef ff_log2_16bit

53 # define ff_log2_16bit av_log2

54 # endif

55 #endif /* ff_log2 */

56 #endif

57 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */

59 extern const uint8_t ff_log2_tab[256];

61 #ifndef ff_log2

62 #define ff_log2 ff_log2_c

63 #if !defined( _MSC_VER )

64 static av_always_inline av_const int ff_log2_c(unsigned int v)

65 {

66 int n = 0;

67 if (v & 0xffff0000) {

68 v >>= 16;

69 n += 16;

70 }

71 if (v & 0xff00) {

72 v >>= 8;

73 n += 8;

74 }

75 n += ff_log2_tab[v];

77 return n;

78 }

79 #else

80 static av_always_inline av_const int ff_log2_c(unsigned int v)

81 {

82 unsigned long n;

83 _BitScanReverse(&n, v|1);

84 return n;

85 }

86 #define ff_log2_16bit av_log2

87 #endif

88 #endif

90 #ifndef ff_log2_16bit

91 #define ff_log2_16bit ff_log2_16bit_c

92 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)

93 {

94 int n = 0;

95 if (v & 0xff00) {

96 v >>= 8;

97 n += 8;

98 }

99 n += ff_log2_tab[v];

100

101 return n;

102 }

103 #endif

104

105 #define av_log2 ff_log2

106 #define av_log2_16bit ff_log2_16bit

107

108 /**

109 * @}

110 */

111

112 /**

113 * @addtogroup lavu_math

114 * @{

115 */

116

117 #if HAVE_FAST_CLZ

118 #if AV_GCC_VERSION_AT_LEAST(3,4)

119 #ifndef ff_ctz

120 #define ff_ctz(v) __builtin_ctz(v)

121 #endif

122 #elif defined( __INTEL_COMPILER )

123 #ifndef ff_ctz

124 #define ff_ctz(v) _bit_scan_forward(v)

125 #endif

126 #endif

127 #endif

128

129 #ifndef ff_ctz

130 #define ff_ctz ff_ctz_c

131 #if !defined( _MSC_VER )

132 static av_always_inline av_const int ff_ctz_c(int v)

133 {

134 int c;

135

136 if (v & 0x1)

137 return 0;

138

139 c = 1;

140 if (!(v & 0xffff)) {

141 v >>= 16;

142 c += 16;

143 }

144 if (!(v & 0xff)) {

145 v >>= 8;

146 c += 8;

147 }

148 if (!(v & 0xf)) {

149 v >>= 4;

150 c += 4;

151 }

152 if (!(v & 0x3)) {

153 v >>= 2;

154 c += 2;

155 }

156 c -= v & 0x1;

157

158 return c;

159 }

160 #else

161 static av_always_inline av_const int ff_ctz_c( int v )

162 {

163 unsigned long c;

164 _BitScanForward(&c, v);

165 return c;

166 }

167 #endif

168 #endif

169

170 /**

171 * Trailing zero bit count.

172 *

173 * @param v input value. If v is 0, the result is undefined.

174 * @return the number of trailing 0-bits

175 */

176 int av_ctz(int v);

177

178 /**

179 * @}

180 */

181 #endif /* AVUTIL_INTMATH_H */

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