/* number.c : PUBLIC DOMAIN - Jon MAyo - August 24, 2006
 * converts a number to a string with some formatting */
#include <limits.h>
#include <assert.h>

#define ITOA_UPPER	64
#define ITOA_ZEROLEAD	128
#define ITOA_LEFT	65536L		/* left justify */
#define ITOA_SIGN	131072L		/* display sign character */
#define ITOA_SPECIAL	262144L
#define ITOA_WIDTH(w)	(((w)&255)<<8)
#define ITOA_RADIX(r)	(((r)&63))

char *itoa_s(int n, char *buf, unsigned len, unsigned long flags_or_radix) {
	char tmp[sizeof n * CHAR_BIT]; /* you can use 8 instead of CHAR_BIT */
	const char *digits = "0123456789abcdefghijklmnopqrstuvwxyz";
	unsigned radix=flags_or_radix&63;
	int width=(flags_or_radix>>8)&255;
	unsigned i, negative;
	char *str;

	if(radix>36 || radix<2) return 0;
	if(flags_or_radix&ITOA_UPPER) {
		digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		flags_or_radix&=~ITOA_UPPER; /* clear */
	}

	negative=n<0;
	if(negative)
		n=-n;
	i=0;
	do {
		tmp[i++]=digits[n%radix];
		n/=radix;
	} while(n);

	str=buf;

	if(!(flags_or_radix&ITOA_LEFT) && !(flags_or_radix&ITOA_ZEROLEAD))  {
		while(width>i) {
			*str++=' ';
			width--;
		}
	}

	if(negative) {
		*str++='-';
		width--;
	} else if(flags_or_radix&ITOA_SIGN)  {
		*str++='+';
		width--;
	}

	if(flags_or_radix&ITOA_ZEROLEAD)  {
		while(width>i) {
			*str++='0';
			width--;
		}
	}

	while(i-->0) {
		*str++=tmp[i];	
		width--;
	}
	
	if(flags_or_radix&ITOA_LEFT)  {
		while(width--) {
			*str++=' ';
		}
	}

	*str=0;
	return buf;
}

#ifdef STAND_ALONE
#include <stdlib.h>
#include <stdio.h>
#define NR(x) (sizeof(x)/sizeof*(x))
int main(int argc, char **argv) {
	int n, i, j;
	char buf[256];
	const unsigned test[] = {2, 8, 10, 16, 36};
	for(i=1;i<argc;i++) {
		n=strtol(argv[i], 0, 0);
		for(j=0;j<NR(test);j++)
			printf("%2u:%s*\n", test[j], itoa_s(n, buf, sizeof buf, test[j] | ITOA_WIDTH(8)));
	}
}
#endif