os-k/src/kaleid/common/itoa.c

//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Authors:    spectral`                                                     //
//              NeoX                                                          //
//                                                                            //
//  Desc:       Conversion utilities - itoa family                            //
//----------------------------------------------------------------------------//

#include <kaleid.h>

//
//  Digits table for bases <=36
//
static const char digits[36] =
        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
//
//  Integer to string in any base between 2 and 36 (included)
//
#if defined(_NEED_ITOA)
char *itoa(int i, char *str, int base)
#elif defined(_NEED_LTOA)
char *ltoa(long i, char *str, int base)
#elif defined(_NEED_UTOA)
char *utoa(uint i, char *str, int base)
#elif defined(_NEED_ULTOA)
char *ultoa(ulong i, char *str, int base)
#else
#error "What am I supposed to declare?" 
#endif
{
#if defined(_NEED_ITOA) || defined(_NEED_LTOA)
    int neg = 0;
#endif

    char *orig = str;

    if (base < 2 || base > 36)
        return NULL;

#if defined(_NEED_ITOA) || defined(_NEED_LTOA)
    // deal with negatives
    if (i < 0) {
        neg = 1;
        i = -i;
    }
#endif
    
    // deal with zero separately
    if (i == 0) {
        *str++ = '0';
    }
    
    // compute digits... in reverse order
    while (i > 0) {
        *str++ = digits[i % base];
        i /= base;
    }

#if defined(_NEED_ITOA) || defined(_NEED_LTOA)
    if (neg) *str++ = '-';
#endif

    *str = '\0';

    return reverse(orig);
}