[Libclc-developers] contribution(?): string function ultostr()

[Jan E. <je...@li...>]

Hi,

copied this from my personal lib as I thought
this might be worth sharing, no?

/*=============================================================================
ultostr
  by Jan "Hirogen2" Engelhardt <hirogen2 at gmx de>, 2003
  -- distributed under the Frontier Artistic License and GNU General Public
  -- License. See doc/FAL1.txt and doc/GPL2.txt for details.
-------------------------------------------------------------------------------
NAME
    ultostr - convert an unsigned long integer to a string

SYNOPSIS
    unsigned char *ultostr(unsigned long num, unsigned long base,
     unsigned char *ptr, size_t size);

DESCRIPTION
    The ultostr() function converts the number NUM to a string, in
    base BASE notation. BASE must be between 2 and 36 inclusive. To
    summarize it, this function does (nearly) exactly the opposite
    of strtoul().

    The output is written to the location pointed to by PTR, whose
    length is passed in SIZE. SIZE is the number of bytes, including
    space for a trailing '\0'. No more bytes than (SIZE - 1) are
    written. The output is null-padded in front.

RETURN VALUE
    ultostr() returns PTR on success, or NULL on error. ERANGE is
    returned if BASE is < 2 or > 36. EFAULT is returned if PTR is
    NULL.

EXAMPLE
    unsigned char buf[12];
    memset(buf, 0, 12);
    printf("%s\n", ultostr(170, 2, 12));

    Prints 00010101010 (11 chars).
=============================================================================*/
#include <errno.h>
#include <stdio.h>

unsigned char *ultostr(unsigned long num, unsigned long base,
 unsigned char *ptr, size_t size) {
  unsigned char *sym = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ",
   *startp = ptr + size - 2;
  if(base < 2 || base > 36) { errno = ERANGE; return NULL; }
  if(ptr == NULL) { errno = EFAULT; return NULL; }
  while(--size > 0) {
    *ptr = sym[num % base];
    num /= base;
    --ptr;
  }
  return ptr;
}

//==[ End of file ]============================================================


- Jan Engelhardt