sp_comm.c

常用的无损压缩算法源代码

/* = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = */

/*               S + P   I M A G E   C O M P R E S S I O N             */

/* = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = */
/*     > > > > >    ANSI C version  1.06  -  05/30/95    < < < < <     */

/*                File shared by the encoder and decoder               */

/*   Amir Said - [e-mail]                            */
/*   Faculty of Electrical Engineering                                 */
/*   University of Campinas (UNICAMP) - Campinas, SP 13081, Brazil     */

/*   William A. Pearlman - [e-mail]                       */
/*   Dept. of Electrical, Computer, and Systems Engineering            */
/*   Rensselaer Polytechnic Institute - Troy, NY 12180, USA            */

/*     Copyright (c) 1995 Amir Said & William A. Pearlman              */

/*
   This program is Copyright (c) by Amir Said and William A. Pearlman.
   It may be freely redistributed in its entirety provided that this
   copyright notice is not removed. It may not be sold for profit or
   incorporated in commercial programs without the written permission
   of the copyright holders. This program is provided as is, without
   any express or implied warranty, without even the warranty of
   fitness for a particular purpose.
*/



/* - - Inclusion - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#include <string.h>
#include <time.h>


/* - - Definitions - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define KEY_2 0x55
#define KEY_3 0x52

#ifndef CLOCKS_PER_SEC
#define CLOCKS_PER_SEC 1e6
#endif

#define NumbSets 28

typedef struct {

  int x, y;

} Image_Coord;

typedef struct {

  int bias, bits;

} Set_Data;


/* - - Static variables  - - - - - - - - - - - - - - - - - - - - - - - */

char * m_msg = "insufficient memory";

char line[80];

int * buffer[2], smooth_image = 0;

Set_Data set_table[NumbSets];


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* - - Functions - - - - - - - - - - - - - - - - - - - - - - - - - - - */

void Error(char * s)
{
  printf("\n\aError: %s\n", s);  exit(1);
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

void Construct_Set_Table(void)
{
  int i, k, b, m;

  set_table[0].bias = set_table[0].bits = 0;
  for (i = 1; i < 4; i++) {
    set_table[i].bias = i;  set_table[i].bits = 1; }

  m = 2;  k = 2;
  for (b = i = 4; i < NumbSets; i++, m++) {
    set_table[i].bias = b;  set_table[i].bits = m;
    set_table[++i].bias = b + k;  set_table[i].bits = m;
    k = b;  b <<= 1;  }
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

int Set(int n)
{
  int k;
  if (n < 0) n = -n;
  if (n < 4) return n;
  for (k = 5; n >= set_table[k].bias; ++k) ;
  return --k;
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

void Select_Quadrant(int q, Image_Coord s,
                     Image_Coord * min, Image_Coord * max)
{
  switch (q) {
    case 0 : min->x = min->y = 0;  break;
    case 1 : min->x = 0;  min->y = s.y;  break;
    case 2 : min->x = s.x;  min->y = 0;  break;
    case 3 : min->x = s.x;  min->y = s.y; }

  max->x = min->x + s.x;   max->y = min->y + s.y;
}


/* = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = */

/* end of file < sp_comm.c > */