compilers/linux86-0.16.17/tests/ucomp.c

   1
   2 /*
   3  *  Uncompress program this is very very fast
   4  *
   5  */
   6
   7 #include <sys/types.h>
   8 #include <sys/stat.h>
   9 #include <fcntl.h>
  10 #include <stdio.h>
  11 #include <malloc.h>
  12
  13 #define MAXLEN 255
  14
  15 #define     maxno  61000U
  16 #define     USE_BSS
  17
  18 #ifdef USE_BSS
  19 unsigned char  fptr[maxno];
  20 #else
  21 unsigned char *fptr;
  22 #endif
  23 FILE *      fd;
  24 int         key;
  25
  26 main(argc, argv)
  27 int argc;
  28 char ** argv;
  29 {
  30 #ifndef USE_BSS
  31    fptr = (unsigned char * ) malloc(maxno);
  32
  33    if( fptr == 0 )
  34    {
  35       perror("Cannot allocate memory");
  36       exit(1);
  37    }
  38 #endif
  39
  40    if( argc < 2 )
  41    {
  42       fd = stdin;
  43       key = getc(fd);
  44       uncompress();
  45    }
  46    else
  47    {
  48       fd = fopen(argv[1], "r" );
  49       if( fd == 0 ) { perror("Open failed"); exit(1); }
  50
  51       key = getc(fd);
  52       uncompress();
  53    }
  54 }
  55
  56 /* \f
  57
  58    Uncompression routine -- v.v.fast
  59 */
  60
  61 uncompress()
  62 {
  63    register unsigned char * mainscan;
  64    register unsigned char * secondscan;
  65    register unsigned char * ptr = (unsigned char * ) fptr;
  66    register unsigned char * eptr = ptr+maxno;
  67    register unsigned int len;
  68    register int ch;
  69
  70    mainscan = ptr;
  71
  72    for(;;)
  73    {
  74       ch = getc(fd);
  75       if(ch == EOF) break;
  76       ch &= 0xFF;
  77       if(ch == key)
  78       {
  79          ch = getc(fd);
  80          if( ch == 0 )
  81             *mainscan++ = key;
  82          else
  83          {
  84             len = (unsigned char) getc(fd);
  85             if( ch & 0x80 )
  86                len += ((unsigned char) getc(fd)) << 8;
  87             secondscan = mainscan - len;
  88             if(len > mainscan - ptr) secondscan += maxno;
  89             len = (unsigned char) ch & 0x7F;
  90             for( ; len>0; len-- )
  91             {
  92                *mainscan++ = *secondscan++;
  93                if( secondscan == eptr ) secondscan = ptr;
  94                if( mainscan == eptr )
  95                   { write(1, ptr, (int)(mainscan-ptr)); mainscan = ptr; }
  96             }
  97          }
  98       }
  99       else
 100          *mainscan++ = ch;
 101
 102       if( mainscan == eptr )
 103          { write(1, ptr, (int)(mainscan-ptr)); mainscan = ptr; }
 104    }
 105    if( mainscan != ptr )
 106       { write(1, ptr, (int)(mainscan-ptr)); mainscan = ptr; }
 107 }
 108