libghost/lifting.c

   1 /**
   2    @file lifting.c
   3    @brief Lifting wavelet transform
   4  */
   5
   6 /* Copyright (C) 2005
   7
   8    This library 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    This library 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 this library; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  21 */
  22
  23
  24 #include "lifting.h"
  25
  26 void lifting_forward(float *x, struct LiftingBasis *basis, int len, int stride)
  27 {
  28    int i,j;
  29    float *r, *rstart; /* residue/modified value */
  30    float *y; /* prediction start */
  31    int stride2 = 2*stride;
  32    /* Prediction */
  33    if (basis->predict_delay > 1)
  34       rstart = x-stride2*(basis->predict_delay-1);
  35    else
  36       rstart = x;
  37    r = rstart;
  38    y = x + 1 - stride2*(basis->predict_length - basis->predict_delay);
  39
  40    for (i=0;i<len;i+=stride2)
  41    {
  42       float sum = 0;
  43       const float *p = basis->predict;
  44       float *y2 = y;
  45       for (j=0;j<basis->predict_length;j++)
  46       {
  47          sum += *p++ * *y2;
  48          y2 += stride2;
  49       }
  50       *r -= sum;
  51       r += stride2;
  52       y += stride2;
  53    }
  54    //return;
  55    /* Update */
  56    r = rstart + 1 - stride2*basis->update_delay;
  57    y = rstart - stride2*(basis->update_length - basis->update_delay);
  58
  59    for (i=0;i<len;i+=stride2)
  60    {
  61       float sum = 0;
  62       const float *p = basis->update;
  63       float *y2 = y;
  64       for (j=0;j<basis->update_length;j++)
  65       {
  66          sum += *p++ * *y2;
  67          y2 += stride2;
  68       }
  69       *r += sum;
  70       r += stride2;
  71       y += stride2;
  72    }
  73 }
  74
  75 void lifting_backward(float *x, struct LiftingBasis *basis, int len, int stride)
  76 {
  77    int i,j;
  78    float *r, *rstart, *ustart; /* residue/modified value */
  79    float *y; /* prediction start */
  80    int stride2 = 2*stride;
  81
  82    if (basis->predict_delay > 1)
  83       rstart = x-2*stride*(basis->predict_delay-1);
  84    else
  85       rstart = x;
  86
  87    /* De-update */
  88    ustart = rstart + 1 - stride2*basis->update_delay;
  89    y = rstart - stride2*(basis->update_length - basis->update_delay);
  90    r = ustart;
  91
  92    for (i=0;i<len;i+=stride2)
  93    {
  94       float sum = 0;
  95       const float *p = basis->update;
  96       float *y2 = y;
  97       for (j=0;j<basis->update_length;j++)
  98       {
  99          sum += *p++ * *y2;
 100          y2 += stride2;
 101       }
 102       *r -= sum;
 103       r += stride2;
 104       y += stride2;
 105    }
 106
 107    /* De-predict */
 108    if (basis->predict_delay > 1)
 109       rstart = ustart-stride2*(basis->predict_delay-1)-1;
 110    else
 111       rstart = ustart-1;
 112    r = rstart;
 113    y = ustart - stride2*(basis->predict_length - basis->predict_delay);
 114
 115    for (i=0;i<len;i+=stride2)
 116    {
 117       float sum = 0;
 118       const float *p = basis->predict;
 119       float *y2 = y;
 120       for (j=0;j<basis->predict_length;j++)
 121       {
 122          sum += *p++ * *y2;
 123          y2 += stride2;
 124       }
 125       *r += sum;
 126       r += stride2;
 127       y += stride2;
 128    }
 129
 130 }
 131