src/external/tng_io/src/compression/vals16.c

   1 /* This code is part of the tng compression routines.
   2  *
   3  * Written by Daniel Spangberg
   4  * Copyright (c) 2010, 2013, The GROMACS development team.
   5  *
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the Revised BSD License.
   9  */
  10
  11
  12 #include "../../include/compression/vals16.h"
  13
  14 /* Coding 32 bit ints in sequences of 16 bit ints. Worst case
  15    the output is 3*nvals long. */
  16 void Ptngc_comp_conv_to_vals16(unsigned int *vals, const int nvals,
  17                                unsigned int *vals16, int *nvals16)
  18 {
  19   int i;
  20   int j=0;
  21   for (i=0; i<nvals; i++)
  22     {
  23       if (vals[i]<=0x7FFFU)
  24         vals16[j++]=vals[i];
  25       else
  26         {
  27           unsigned int lo=(vals[i]&0x7FFFU)|0x8000U;
  28           unsigned int hi=vals[i]>>15;
  29           vals16[j++]=lo;
  30           if (hi<=0x7FFFU)
  31             vals16[j++]=hi;
  32           else
  33             {
  34               unsigned int lohi=(hi&0x7FFFU)|0x8000U;
  35               unsigned int hihi=hi>>15;
  36               vals16[j++]=lohi;
  37               vals16[j++]=hihi;
  38             }
  39         }
  40     }
  41 #if 0
  42   /* Test that things that detect that this is bad really works. */
  43   vals16[0]=0;
  44 #endif
  45   *nvals16=j;
  46 }
  47
  48 void Ptngc_comp_conv_from_vals16(unsigned int *vals16, const int nvals16,
  49                                  unsigned int *vals, int *nvals)
  50 {
  51   int i=0;
  52   int j=0;
  53   while (i<nvals16)
  54     {
  55       if (vals16[i]<=0x7FFFU)
  56         vals[j++]=vals16[i++];
  57       else
  58         {
  59           unsigned int lo=vals16[i++];
  60           unsigned int hi=vals16[i++];
  61           if (hi<=0x7FFFU)
  62             vals[j++]=(lo&0x7FFFU)|(hi<<15);
  63           else
  64             {
  65               unsigned int hihi=vals16[i++];
  66               vals[j++]=(lo&0x7FFFU)|((hi&0x7FFFU)<<15)|(hihi<<30);
  67             }
  68         }
  69     }
  70   *nvals=j;
  71 }