testsuite/quant.c

   1
   2 #include <stdio.h>
   3 #include <math.h>
   4
   5 static int
   6 dequantise (int q, int quant_factor, int quant_offset)
   7 {
   8   if (q == 0) return 0;
   9   if (q < 0) {
  10     return ((q * quant_factor - quant_offset + 2)>>2);
  11   } else {
  12     return (q * quant_factor + quant_offset + 2)>>2;
  13   }
  14 }
  15
  16 static int
  17 quantise (int value, int quant_factor, int quant_offset)
  18 {
  19   unsigned int x;
  20
  21   if (value == 0) return 0;
  22   if (value < 0) {
  23     x = ((-value)<<2) - quant_offset + (quant_factor>>1);
  24     //x = (x*(uint64_t)inv_quant_factor)>>32;
  25     x /= quant_factor;
  26     value = -x;
  27   } else {
  28     x = (value<<2) - quant_offset + (quant_factor>>1);
  29     //x = (x*(uint64_t)inv_quant_factor)>>32;
  30     x /= quant_factor;
  31     value = x;
  32   }
  33   return value;
  34 }
  35
  36 int
  37 main (int argc, char *argv[])
  38 {
  39   int i;
  40   int quant_factor = 128;
  41   int quant_offset = 48;
  42   int q;
  43
  44   for(i=-1000;i<1000;i++){
  45     q = quantise(i,quant_factor,quant_offset);
  46     printf("%d %d\n", i, dequantise(q,quant_factor,quant_offset));
  47   }
  48
  49   return 0;
  50 }
  51