/* See LICENSE file for copyright and license details. */
#include "internals.h"


void
zbset(z_t a, z_t b, size_t bit, int action)
{
	zahl_char_t mask = 1;
	size_t chars;

	chars = FLOOR_BITS_TO_CHARS(bit);
	bit = BITS_IN_LAST_CHAR(bit);
	mask <<= bit;

	SET(a, b);

	if (action) {
		if (zzero(a)) {
			a->used = 0;
			SET_SIGNUM(a, 1);
		}
		if (a->used <= chars) {
			ENSURE_SIZE(a, chars + 1);
			zmemset(a->chars + a->used, 0, chars + 1 - a->used);
			a->used = chars + 1;
		}
	}

	if (action > 0) {
		a->chars[chars] |= mask;
		return;
	} else if (action < 0) {
		a->chars[chars] ^= mask;
	} else if (chars < a->used) {
		a->chars[chars] &= ~mask;
	}

	TRIM_AND_ZERO(a);
}