/* See LICENSE file for copyright and license details. */
#include "lib-common.h"


enum libcharconv_result
libcharconv_yijing_tetragrams(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
{
	uint_least32_t c;
	*n = 0;
	for (; slen--; s++) {
		if ('1' <= s[0] && s[0] <= '3') {
			if (slen == 0u)
				return LIBCHARCONV_INDETERMINATE;
			if ('1' > s[1] || s[1] > '3')
				goto no_match;
			if (slen == 1u)
				return LIBCHARCONV_INDETERMINATE;
			if ('1' > s[2] || s[2] > '3')
				goto no_match;
			if (slen == 2u)
				return LIBCHARCONV_INDETERMINATE;
			if ('1' > s[3] || s[3] > '3')
				goto no_match;
			c = UINT32_C(0x1D306);
			c += (uint_least32_t)(s[3] - '1') *  1u;
			c += (uint_least32_t)(s[2] - '1') *  3u;
			c += (uint_least32_t)(s[1] - '1') *  9u;
			c += (uint_least32_t)(s[0] - '1') * 27u;
			goto conv;
		} else {
		no_match:
			*n += 1u;
		}
	}
no_conv:
	return LIBCHARCONV_NO_CONVERT;

conv:
	if (*n)
		goto no_conv;
	if (*ncp)
		*cp = c;
	*n += 4u;
	*ncp = 1u;
	return LIBCHARCONV_CONVERTED;
}