vp8/encoder/dct.c

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11
  12 #include <math.h>
  13
  14 void vp8_short_fdct4x4_c(short *input, short *output, int pitch)
  15 {
  16     int i;
  17     int a1, b1, c1, d1;
  18     short *ip = input;
  19     short *op = output;
  20
  21     for (i = 0; i < 4; i++)
  22     {
  23         a1 = ((ip[0] + ip[3])<<3);
  24         b1 = ((ip[1] + ip[2])<<3);
  25         c1 = ((ip[1] - ip[2])<<3);
  26         d1 = ((ip[0] - ip[3])<<3);
  27
  28         op[0] = a1 + b1;
  29         op[2] = a1 - b1;
  30
  31         op[1] = (c1 * 2217 + d1 * 5352 +  14500)>>12;
  32         op[3] = (d1 * 2217 - c1 * 5352 +   7500)>>12;
  33
  34         ip += pitch / 2;
  35         op += 4;
  36
  37     }
  38     ip = output;
  39     op = output;
  40     for (i = 0; i < 4; i++)
  41     {
  42         a1 = ip[0] + ip[12];
  43         b1 = ip[4] + ip[8];
  44         c1 = ip[4] - ip[8];
  45         d1 = ip[0] - ip[12];
  46
  47         op[0]  = ( a1 + b1 + 7)>>4;
  48         op[8]  = ( a1 - b1 + 7)>>4;
  49
  50         op[4]  =((c1 * 2217 + d1 * 5352 +  12000)>>16) + (d1!=0);
  51         op[12] = (d1 * 2217 - c1 * 5352 +  51000)>>16;
  52
  53         ip++;
  54         op++;
  55     }
  56 }
  57
  58 void vp8_short_fdct8x4_c(short *input, short *output, int pitch)
  59 {
  60     vp8_short_fdct4x4_c(input,   output,    pitch);
  61     vp8_short_fdct4x4_c(input + 4, output + 16, pitch);
  62 }
  63
  64 void vp8_short_walsh4x4_c(short *input, short *output, int pitch)
  65 {
  66     int i;
  67     int a1, b1, c1, d1;
  68     int a2, b2, c2, d2;
  69     short *ip = input;
  70     short *op = output;
  71
  72
  73     for (i = 0; i < 4; i++)
  74     {
  75         a1 = ((ip[0] + ip[2])<<2);
  76         d1 = ((ip[1] + ip[3])<<2);
  77         c1 = ((ip[1] - ip[3])<<2);
  78         b1 = ((ip[0] - ip[2])<<2);
  79
  80         op[0] = a1 + d1 + (a1!=0);
  81         op[1] = b1 + c1;
  82         op[2] = b1 - c1;
  83         op[3] = a1 - d1;
  84         ip += pitch / 2;
  85         op += 4;
  86     }
  87
  88     ip = output;
  89     op = output;
  90
  91     for (i = 0; i < 4; i++)
  92     {
  93         a1 = ip[0] + ip[8];
  94         d1 = ip[4] + ip[12];
  95         c1 = ip[4] - ip[12];
  96         b1 = ip[0] - ip[8];
  97
  98         a2 = a1 + d1;
  99         b2 = b1 + c1;
 100         c2 = b1 - c1;
 101         d2 = a1 - d1;
 102
 103         a2 += a2<0;
 104         b2 += b2<0;
 105         c2 += c2<0;
 106         d2 += d2<0;
 107
 108         op[0] = (a2+3) >> 3;
 109         op[4] = (b2+3) >> 3;
 110         op[8] = (c2+3) >> 3;
 111         op[12]= (d2+3) >> 3;
 112
 113         ip++;
 114         op++;
 115     }
 116 }