FFmpeg: libavutil/softfloat.h Source File

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libavutil

softfloat.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_SOFTFLOAT_H

22 #define AVUTIL_SOFTFLOAT_H

24 #include <stdint.h>

25 #include "common.h"

27 #define MIN_EXP -126

28 #define MAX_EXP 126

29 #define ONE_BITS 29

31 typedef struct SoftFloat{

32 int32_t exp;

33 int32_t mant;

34 }SoftFloat;

36 static av_const SoftFloat av_normalize_sf(SoftFloat a){

37 if(a.mant){

38 #if 1

39 while((a.mant + 0x20000000U)<0x40000000U){

40 a.mant += a.mant;

41 a.exp -= 1;

42 }

43 #else

44 int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));

45 a.exp -= s;

46 a.mant <<= s;

47 #endif

48 if(a.exp < MIN_EXP){

49 a.exp = MIN_EXP;

50 a.mant= 0;

51 }

52 }else{

53 a.exp= MIN_EXP;

54 }

55 return a;

56 }

58 static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){

59 #if 1

60 if(a.mant + 0x40000000 < 0){

61 a.exp++;

62 a.mant>>=1;

63 }

64 return a;

65 #elif 1

66 int t= a.mant + 0x40000000 < 0;

67 return (SoftFloat){a.exp+t, a.mant>>t};

68 #else

69 int t= (a.mant + 0x40000000U)>>31;

70 return (SoftFloat){a.exp+t, a.mant>>t};

71 #endif

72 }

74 /**

75 * @return Will not be more denormalized than a+b. So if either input is

76 * normalized, then the output will not be worse then the other input.

77 * If both are normalized, then the output will be normalized.

78 */

79 static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){

80 a.exp += b.exp;

81 a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;

82 return av_normalize1_sf(a);

83 }

85 /**

86 * b has to be normalized and not zero.

87 * @return Will not be more denormalized than a.

88 */

89 static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){

90 a.exp -= b.exp+1;

91 a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;

92 return av_normalize1_sf(a);

93 }

95 static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){

96 int t= a.exp - b.exp;

97 if(t<0) return (a.mant >> (-t)) - b.mant ;

98 else return a.mant - (b.mant >> t);

99 }

100

101 static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){

102 int t= a.exp - b.exp;

103 if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});

104 else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )});

105 }

106

107 static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){

108 return av_add_sf(a, (SoftFloat){b.exp, -b.mant});

109 }

110

111 //FIXME sqrt, log, exp, pow, sin, cos

112

113 static inline av_const SoftFloat av_int2sf(int v, int frac_bits){

114 return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});

115 }

116

117 /**

118 * Rounding is to -inf.

119 */

120 static inline av_const int av_sf2int(SoftFloat v, int frac_bits){

121 v.exp += frac_bits - ONE_BITS;

122 if(v.exp >= 0) return v.mant << v.exp ;

123 else return v.mant >>(-v.exp);

124 }

125

126 #endif /* AVUTIL_SOFTFLOAT_H */

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