/* File: codrle3.c   Author: David Bourgin   Creation date: 1/2/94   Last update: 24/7/95   Purpose: Example of RLE type 3 encoding with a file source to compress.*/#include <stdio.h>/* For routines printf,fputc,fread,fwrite and rewind */#include <memory.h>/* For routines memset,memcpy */#include <stdlib.h>/* For routine exit *//* Error codes sent to the caller */#define NO_ERROR      0#define BAD_FILE_NAME 1#define BAD_ARGUMENT  2/* Useful constants */#define FALSE 0#define TRUE  1#define MAX_FRAME_SIZE  256/* Global variables */FILE *source_file,*dest_file;unsigned int index=0,             buffer_read_size=0;unsigned char buffer_read[3*256];typedef struct { unsigned int array_size;                 unsigned char *array_val;               } t_tab;#define ARRAY_SIZE(array)  ((array).array_size)#define ARRAY_VAL(array)  ((array).array_val)#define ARE_EQUAL(array1,array2)  ((ARRAY_SIZE(array1)==ARRAY_SIZE(array2))&&(!memcmp(ARRAY_VAL(array1),ARRAY_VAL(array2),ARRAY_SIZE(array1))))/* Pseudo procedures */#define size_remaining_to_read() (buffer_read_size-index)#define read_block()  { if (!size_remaining_to_read())\                           { buffer_read_size=fread(buffer_read,1,sizeof(buffer_read),source_file);\                             index=0;\                           }\                      }#define move_index(i)  (index=(i))#define beginning_of_data()  { (void)rewind(source_file); buffer_read_size=0; index=0; }#define end_of_data()  (size_remaining_to_read()?FALSE:(index=0,!(buffer_read_size=fread(buffer_read,1,sizeof(buffer_read),source_file))))#define read_byte()  ((unsigned char)(end_of_data()?EOF:buffer_read[index++]))#define read_array(array,nb_to_read)  { ARRAY_SIZE(array)=(nb_to_read);\                                        ARRAY_VAL(array)= &(buffer_read[index]);\                                        index += (nb_to_read);\                                      }#define write_byte(x)  ((void)fputc((unsigned char)(x),dest_file))#define write_array(array)  ((void)fwrite(ARRAY_VAL(array),1,ARRAY_SIZE(array),dest_file))#define fill_block()  { (void)memcpy(buffer_read,&(buffer_read[index]),size_remaining_to_read());\                        buffer_read_size=fread(&(buffer_read[size_remaining_to_read()]),1,sizeof(buffer_read)-size_remaining_to_read(),source_file)+size_remaining_to_read();\                        index=0;\                      }void rle3look_for_occurr(frame_nb,frame_size,                         repetition_ok)/* Returned parameters: 'frame_nb', 'frame_size' and 'repetition_ok' are modified   Action: Looks in the byte buffer if there's a frame repetition   where size and repetition are respectively in 'frame_size' and 'frame_nb'.   Whenever a repetition is met, 'repetition_ok' returns 'TRUE' otherwise 'repetition_ok' returns 'FALSE'   Errors: Whenever there are no multiple frames then 'frame_nb' won't be modified   If there is a repetition such as (frame_nb-1)*frame_size>3 the buffer is   completed so that it contains only one occurrence of the frame a its beginning.   (The repetitions have been flushed by caliing 'fill_block').*/unsigned int *frame_nb,*frame_size;int *repetition_ok;{ int array_equality;  t_tab array1,array2;  *frame_size=1;  *repetition_ok=FALSE;  while ((*frame_size<=MAX_FRAME_SIZE)&&(size_remaining_to_read()>=(*frame_size << 1))&&(!*repetition_ok))        { read_array(array1,*frame_size);          read_array(array2,*frame_size);          if (array_equality=ARE_EQUAL(array1,array2))             { *frame_nb=2;               while ((size_remaining_to_read()>=*frame_size)&&(*frame_nb<=255)&&(array_equality))                     { if ((*frame_nb-1)*(*frame_size)>3)                          { if (*repetition_ok)                               move_index(*frame_size);                            else { *repetition_ok=TRUE;                                   move_index((*frame_nb-1)*(*frame_size));                                 }                            fill_block();                            move_index(*frame_size);                          }                       read_array(array2,*frame_size);                       if (array_equality=ARE_EQUAL(array1,array2))                          (*frame_nb)++;                     }               if ((*frame_nb-1)*(*frame_size)>3)                  { if (*repetition_ok)                       { if (array_equality)                            { move_index(*frame_size);                              fill_block();                            }                       }                    else { *repetition_ok=TRUE;                           move_index((*frame_nb-1)*(*frame_size));                           fill_block();                         }                    (*frame_size)--;                  }                             /* Specify to the caller there was a repetition */             }          (*frame_size)++;          move_index(0);        }}void rle3write_non_rep(header_byte,non_repeated_byte)/* Returned parameters: None   Action: Writes in the output compression stream the byte 'non_repeated_byte'   'header_byte' is used as marker as defined in RLE 3 method   Errors: An input/output error could disturb the running of the program*/unsigned char header_byte,non_repeated_byte;{ if (non_repeated_byte==header_byte)     { write_byte(header_byte);       write_byte(0);       write_byte(0);     }  else write_byte(non_repeated_byte);}void rle3write_rep(header_byte,frame,repetition)/* Returned parameters: None   Action: Writes in the output compression stream 'repetition' times 'frame' which size is given by 'frame_size'   'header_byte' is used as marker as defined in RLE 3 method   Errors: An input/output error could disturb the running of the program*/unsigned char header_byte;t_tab frame;unsigned int repetition;{ write_byte(header_byte);  write_byte(repetition-1);  write_byte(ARRAY_SIZE(frame)-1);  write_array(frame);}void rle3encoding()/* Returned parameters: None   Action: Compresses with RLE type 3 method all bytes read by the function 'read_byte'   Errors: An input/output error could disturb the running of the program*/{ register unsigned int i;  unsigned long int occurrence_table[256];  unsigned char header_byte;  t_tab frame;  unsigned int frame_nb,frame_size;  int repetition_valid;  if (!end_of_data())        /* Is there at least a byte to analyze? */     {                       /* Sets up the occurrence numbers of all bytes to 0 */       (void)memset((char *)occurrence_table,0,sizeof(occurrence_table));                             /* This is the same to fill 'occurrence_table' to 0.                                It's fastest than to loop 256 times */       while (!end_of_data())/* Valids the occurrences in 'occurrence_table' in regard to the data to compress */             { header_byte=read_byte();               occurrence_table[header_byte]++;             }       header_byte=0;       for (i=1;i<=255;i++)           if (occurrence_table[i]<occurrence_table[header_byte])              header_byte=i;       write_byte(header_byte);       beginning_of_data();       read_block();       while (size_remaining_to_read())             { rle3look_for_occurr(&frame_nb,&frame_size,&repetition_valid);               if (repetition_valid)                             /* Was there a repetition? */                  { read_array(frame,frame_size);                    rle3write_rep(header_byte,frame,frame_nb);                  }               else          /* No pattern repetition */                    rle3write_non_rep(header_byte,read_byte());               fill_block(); /* All new analysis must start at 0 in the buffer */             }     }}void help()/* Returned parameters: None   Action: Displays the help of the program and then stops its running   Errors: None*/{ printf("This utility enables you to compress a file by using RLE type 3 method\n");  printf("as given in 'La Video et Les Imprimantes sur PC'\n");  printf("\nUse: codrle3 source target\n");  printf("source: Name of the file to compress\n");  printf("target: Name of the compressed file\n");}int main(argc,argv)/* Returned parameters: Return an error code (0=None)   Action: Main procedure   Errors: Detected, handled and an error code is returned, if any*/int argc;char *argv[];{ if (argc!=3)     { help();       exit(BAD_ARGUMENT);     }  else if ((source_file=fopen(argv[1],"rb"))==NULL)          { help();            exit(BAD_FILE_NAME);          }       else if ((dest_file=fopen(argv[2],"wb"))==NULL)               { help();                 exit(BAD_FILE_NAME);               }            else { rle3encoding();                   fclose(source_file);                   fclose(dest_file);                 }  printf("Execution of codrle3 completed.\n");  return (NO_ERROR);}