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  1. /*
  2.  * portable IEEE float/double read/write functions
  3.  *
  4.  * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * portable IEEE float/double read/write functions
  26.  */
  27.  
  28. #include <stdint.h>
  29. #include "common.h"
  30. #include "mathematics.h"
  31. #include "intfloat_readwrite.h"
  32.  
  33. double av_int2dbl(int64_t v){
  34.     if((uint64_t)v+v > 0xFFEULL<<52)
  35.         return NAN;
  36.     return ldexp(((v&((1LL<<52)-1)) + (1LL<<52)) * (v>>63|1), (v>>52&0x7FF)-1075);
  37. }
  38.  
  39. float av_int2flt(int32_t v){
  40.     if((uint32_t)v+v > 0xFF000000U)
  41.         return NAN;
  42.     return ldexp(((v&0x7FFFFF) + (1<<23)) * (v>>31|1), (v>>23&0xFF)-150);
  43. }
  44.  
  45. double av_ext2dbl(const AVExtFloat ext){
  46.     uint64_t m = 0;
  47.     int e, i;
  48.  
  49.     for (i = 0; i < 8; i++)
  50.         m = (m<<8) + ext.mantissa[i];
  51.     e = (((int)ext.exponent[0]&0x7f)<<8) | ext.exponent[1];
  52.     if (e == 0x7fff && m)
  53.         return NAN;
  54.     e -= 16383 + 63;        /* In IEEE 80 bits, the whole (i.e. 1.xxxx)
  55.                              * mantissa bit is written as opposed to the
  56.                              * single and double precision formats. */
  57.     if (ext.exponent[0]&0x80)
  58.         m= -m;
  59.     return ldexp(m, e);
  60. }
  61.  
  62. int64_t av_dbl2int(double d){
  63.     int e;
  64.     if     ( !d) return 0;
  65.     else if(d-d) return 0x7FF0000000000000LL + ((int64_t)(d<0)<<63) + (d!=d);
  66.     d= frexp(d, &e);
  67.     return (int64_t)(d<0)<<63 | (e+1022LL)<<52 | (int64_t)((fabs(d)-0.5)*(1LL<<53));
  68. }
  69.  
  70. int32_t av_flt2int(float d){
  71.     int e;
  72.     if     ( !d) return 0;
  73.     else if(d-d) return 0x7F800000 + ((d<0)<<31) + (d!=d);
  74.     d= frexp(d, &e);
  75.     return (d<0)<<31 | (e+126)<<23 | (int64_t)((fabs(d)-0.5)*(1<<24));
  76. }
  77.  
  78. AVExtFloat av_dbl2ext(double d){
  79.     struct AVExtFloat ext= {{0}};
  80.     int e, i; double f; uint64_t m;
  81.  
  82.     f = fabs(frexp(d, &e));
  83.     if (f >= 0.5 && f < 1) {
  84.         e += 16382;
  85.         ext.exponent[0] = e>>8;
  86.         ext.exponent[1] = e;
  87.         m = (uint64_t)ldexp(f, 64);
  88.         for (i=0; i < 8; i++)
  89.             ext.mantissa[i] = m>>(56-(i<<3));
  90.     } else if (f != 0.0) {
  91.         ext.exponent[0] = 0x7f; ext.exponent[1] = 0xff;
  92.         if (!isinf(f))
  93.             ext.mantissa[0] = ~0;
  94.     }
  95.     if (d < 0)
  96.         ext.exponent[0] |= 0x80;
  97.     return ext;
  98. }
  99.