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From: CBFalconer
Subject: GPC and GNU plotutils - problem
Date: 23 Mar 2005, 20:05:41

"Prof A Olowofoyeku (The African Chief)" wrote:
> On 22 Mar 2005 at 22:28, Frank Heckenbach  wrote:
> [...]
>> Of course, you could also convert the octal to (hexa)decimal
>> numbers.
> [...]
> 
> Can we have a series of conversion routines (perhaps in gpcutil.pas)?
> octal2hex
> hex2octal
> int2octal
> octal2int

Here is some C code to do that, together with demo and testing
routines.  Totally portable. Use as you wish.

/* Routines to display values in various bases         */
/* with some useful helper routines.                   */
/* by C.B. Falconer, 19 Sept. 2001                     */
/* Released to public domain.  Attribution appreciated */

#include <stdio.h>
#include <string.h>
#include <limits.h>  /* ULONG_MAX etc. */

/* ======================= */
/* reverse string in place */
size_t revstring(char *stg)
{
   char  *last, temp;
   size_t lgh;

   lgh = strlen(stg);
   if (lgh > 1) {
      last = stg + lgh;        /* points to '\0' */
      while (last-- > stg) {
         temp = *stg; *stg++ = *last; *last = temp;
      }
   }
   return lgh;
} /* revstring */

/* ============================================ */
/* Mask and convert digit to hex representation */
/* Output range is 0..9 and a..f only           */
int hexify(unsigned int value)
{
   static char hexchars[] = "0123456789abcdef";

   return (hexchars[value & 0xf]);
} /* hexify */

/* ================================================== */
/* convert unsigned number to string in various bases */
/* 2 <= base <= 16, controlled by hexify()            */
/* Returns actual output string length                */
size_t basedisplay(unsigned long number, unsigned int base,
                   char *stg, size_t maxlgh)
{
   char *s;

   /* assert (stg[maxlgh]) is valid storage */
   s = stg;
   if (maxlgh && base)
      do {
         *s = hexify(number % base);
         s++;
      } while (--maxlgh && (number = number / base) );
   *s = '\0';
   revstring(stg);
   return (s - stg);
} /* basedisplay */

/* ================================================ */
/* convert signed number to string in various bases */
/* 2 <= base <= 16, controlled by hexify()          */
/* Returns actual output string length              */
size_t signbasedisplay(long number, unsigned int base,
                       char * stg, size_t maxlgh)
{
   char         *s;
   size_t        lgh;
   unsigned long n;

   s = stg; lgh = 0;
   n = (unsigned long)number;
   if (maxlgh && (number < 0L)) {
      *s++ = '-';
      maxlgh--;
      n = -(unsigned long)number;
      lgh = 1;
   }
   lgh = lgh + basedisplay(n, base, s, maxlgh);
   return lgh;
} /* signbaseddisplay */


/* ==================== */
/* flush to end-of-line */
int flushln(FILE *f)
{
   int ch;

   while ('\n' != (ch = fgetc(f)) && (EOF != ch)) /* more */;
   return ch;
} /* flushln */

/* ========== END of generically useful routines ============ */

/* ========================= */
/* Prompt and await <return> */
static void nexttest(char *prompt)
{
   static char empty[] = "";

   if (NULL == prompt) prompt = empty;
   printf("\nHit return for next test: %s", prompt);
   fflush(stdout);
   flushln(stdin);
} /* nexttest */

/* ============================== */
/* Display a value and its length */
static void show(char *caption, int sz, char *stg)
{
   if ((unsigned)sz != strlen(stg))
      printf("Something is wrong with the sz value\n");
   printf("%s: sz = %2d \"%s\"\n", caption, sz, stg);
} /* show */

/* =========== */
/* exercise it */
int main(void)
{
#define LGH   40
#define VALUE 1234567890

   char         stg[LGH];
   unsigned int base;
   int          sz;

   printf("\nExercising basedisplay routine\n");
   printf("\nbase sz value\n");
   for (base = 2; base <= 16; base++) {
      sz = (int)basedisplay(VALUE, base, stg, LGH - 1);
      printf("%2d   %2d %s\n", base, sz, stg);
   }

   nexttest("ULONG_MAX");
   for (base = 8; base <= 16; base++) {
      sz = (int)basedisplay(ULONG_MAX, base, stg, LGH - 1);
      printf("%2d   %2d %s\n", base, sz, stg);
   }

   basedisplay(0, 10, stg, 3);
   printf("\nzero %s\n", stg);

   basedisplay(VALUE, 10, stg, 3);
   printf("3 lsdigits only, base 10 %s\n", stg);

   printf("\nBad calls:\n");

   sz = (int)basedisplay(VALUE, 10, stg, 0);
   show("0 length field", sz, stg);

   sz = (int)basedisplay(VALUE, 1, stg, 20);
   show("base 1, lgh 20", sz, stg);

   sz = (int)basedisplay(VALUE, 0, stg, 20);
   show("base 0, lgh 20", sz, stg);

   sz = (int)signbasedisplay(-1234, 10, stg, 0);
   show("0 lgh fld, -ve", sz, stg);

   sz = (int)signbasedisplay(-1234, 10, stg, 2);
   show("truncate -1234", sz, stg);

   nexttest("System limits");

   sz = (int)signbasedisplay(SCHAR_MIN, 10, stg, 20);
   show("SCHAR_MIN     ", sz, stg);

   sz = (int)signbasedisplay(SCHAR_MAX, 10, stg, 20);
   show("SCHAR_MAX     ", sz, stg);

   sz = (int)signbasedisplay(UCHAR_MAX, 10, stg, 20);
   show("UCHAR_MAX     ", sz, stg);

   sz = (int)signbasedisplay(CHAR_MIN,  10, stg, 20);
   show("CHAR_MIN      ", sz, stg);

   sz = (int)signbasedisplay(CHAR_MAX,  10, stg, 20);
   show("CHAR_MAX      ", sz, stg);

   sz = (int)signbasedisplay(MB_LEN_MAX, 10, stg, 20);
   show("MB_LEN_MAX    ", sz, stg);

   sz = (int)signbasedisplay(SHRT_MIN,  10, stg, 20);
   show("SHRT_MIN      ", sz, stg);

   sz = (int)signbasedisplay(SHRT_MAX,  10, stg, 20);
   show("SHRT_MAX      ", sz, stg);

   sz = (int)signbasedisplay(USHRT_MAX, 10, stg, 20);
   show("USHRT_MAX     ", sz, stg);

   sz = (int)signbasedisplay(INT_MIN,   10, stg, 20);
   show("INT_MIN       ", sz, stg);

   sz = (int)signbasedisplay(INT_MAX,   10, stg, 20);
   show("INT_MAX       ", sz, stg);

   sz = (int)signbasedisplay(INT_MAX,   10, stg, 20);
   show("INT_MAX       ", sz, stg);

   sz = (int)    basedisplay(UINT_MAX,  10, stg, 20);
   show("UINT_MAX      ", sz, stg);

   sz = (int)signbasedisplay(LONG_MIN,  10, stg, 20);
   show("LONG_MIN      ", sz, stg);

   sz = (int)signbasedisplay(LONG_MAX,  10, stg, 20);
   show("LONG_MAX      ", sz, stg);

   sz = (int)    basedisplay(ULONG_MAX, 10, stg, 20);
   show("ULONG_MAX     ", sz, stg);

   nexttest("DONE");
   return 0;
} /* main */

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