1 /**

     2  *     $Id: hex2chars.c,v 1.1.1.1 2008-04-28 17:32:53 mbroeker Exp $

     3  * $Source: /development/c/demos/hex2chars.c,v $

     4  *

     5  */

     6 

     7 #include <stdio.h>

     8 #include <stdlib.h>

     9 #include <string.h>

    10 #include <math.h>

    11 

    12 #ifndef RUNS

    13 #define RUNS 16

    14 #endif

    15 

    16 /*

    17  * =708== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 13 from 1)

    18  * ==708== malloc/free: in use at exit: 352 bytes in 32 blocks.

    19  * ==708== malloc/free: 48 allocs, 16 frees, 3,680 bytes allocated.

    20  * ==708== For counts of detected errors, rerun with: -v

    21  * ==708== searching for pointers to 32 not-freed blocks.

    22  * ==708== checked 68,684 bytes.

    23  */

    24 

    25 const char *characters = "xuzicjklmneopbdaqfrstvgwhy";

    26 

    27 char *remap_works (char *str, int slen)

    28 {

    29     int i;

    30     int pos;

    31     static char *s;

    32 

    33     if ((s = malloc (slen + 1)) == NULL)

    34         return NULL;

    35 

    36     for (i = 0; i < slen; i++) {

    37         if (str[i] >= 'a') {

    38             pos = str[i] - 'a';

    39             s[i] = characters[pos];

    40         } else {

    41             /*

    42              * Let numbers asis

    43              */

    44             s[i] = str[i];

    45         }

    46     }

    47 

    48     s[i] = 0;

    49     return s;

    50 }

    51 

    52 char *remap_works_not (char *str, int slen)

    53 {

    54     int i, j;

    55     double value;

    56     double *table;

    57     static char *s;

    58 

    59     int clen = strlen (characters);

    60 

    61     if ((s = malloc (slen + 1)) == NULL)

    62         return NULL;

    63 

    64     if ((table = calloc (clen, sizeof (double))) == NULL)

    65         return NULL;

    66 

    67     for (i = 0; i < clen; i++)

    68         table[i] = cos ('a' + i);

    69 

    70     for (i = 0; i < slen; i++) {

    71         if (str[i] >= 'a') {

    72             value = cos (str[i]);

    73             for (j = 0; j < clen; j++) {

    74                 /*

    75                  * flip and expand characters

    76                  */

    77                 s[i] = '*';

    78                 if (value == table[j]) {

    79                     s[i] = characters[j];

    80                     break;

    81                 }

    82 

    83                 if ((fabs (value - table[j])) < 0.001) {

    84                     s[i] = characters[j];

    85                     break;

    86                 }

    87             }

    88         } else {

    89             /*

    90              * Let numbers asis

    91              */

    92             s[i] = str[i];

    93         }

    94     }

    95 

    96     s[i] = 0;

    97 

    98     if (table != NULL)

    99         free (table);

   100 

   101     return s;

   102 }

   103 

   104 int main (int argc, char **argv)

   105 {

   106     int i;

   107     int len;

   108     char *start;

   109     char *end;

   110 

   111     if (argc != 2) {

   112         printf ("Usage: %s <string>\n", argv[0]);

   113         exit (0);

   114     }

   115 

   116     start = argv[1];

   117     len = strlen (start);

   118 

   119     printf ("\n  --- REMAP_WORKS FINE ---\n\n");

   120     for (i = 0; i < RUNS; i++) {

   121         if ((end = remap_works (start, len)) != NULL)

   122             printf ("%s\t<==>\t%s\n", start, end);

   123         start = end;

   124     }

   125 

   126     /*

   127      * reset state

   128      */

   129     start = argv[1];

   130 

   131     printf ("\n  --- REMAP_WORKS_NOT because floating-point comparison is evil at all ---\n\n");

   132     for (i = 0; i < RUNS; i++) {

   133         if ((end = remap_works_not (start, len)) != NULL)

   134             printf ("%s\t<==>\t%s\n", start, end);

   135         start = end;

   136     }

   137 

   138     return 0;

   139 }