Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  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.  */
  20.  
  21. #ifndef AVUTIL_SOFTFLOAT_H
  22. #define AVUTIL_SOFTFLOAT_H
  23.  
  24. #include <stdint.h>
  25. #include "common.h"
  26.  
  27. #define MIN_EXP -126
  28. #define MAX_EXP  126
  29. #define ONE_BITS 29
  30.  
  31. typedef struct SoftFloat{
  32.     int32_t  exp;
  33.     int32_t mant;
  34. }SoftFloat;
  35.  
  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. }
  57.  
  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. }
  73.  
  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. }
  84.  
  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. }
  94.  
  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 */
  127.