binary to hexadecimal

bin2hex.c

#include <stddef.h>

/*
 * Encode binary data into ASCII hexadecimal numbers.
 *
 * Return the number of hexadecimals written in "out". If "outlen" is at least
 * twice as long as "inlen" the result is not truncated.
 */
size_t
bin2hex(char *out, size_t outlen, const unsigned char *in, size_t inlen)
{
	static const char hexmap[] = "0123456789abcdef";
	size_t i, j;

	for (i = 0, j = 0; i < inlen && j + 1 < outlen; i++, j += 2) {
		out[j] = hexmap[in[i] & 0xFU];
		out[j + 1] = hexmap[in[i] >> 4];
	}

	return j;
}