Add zbset

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 48 insertions, 0 deletions

diff --git a/src/zbset.c b/src/zbset.c
new file mode 100644
index 0000000..6833e5f
--- /dev/null
+++ b/src/zbset.c
@@ -0,0 +1,48 @@
+/* See LICENSE file for copyright and license details. */
+#include "internals"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+void
+zbset(z_t a, z_t b, size_t bit, int action)
+{
+	zahl_char_t x = 1;
+	size_t chars;
+
+	chars = FLOOR_BITS_TO_CHARS(bit);
+	bit = BITS_IN_LAST_CHAR(bit);
+	x <<= bit;
+
+	if (a != b)
+		zset(a, b);
+
+	if (action) {
+		if (zzero(a)) {
+			a->used = 0;
+			SET_SIGNUM(a, 1);
+		}
+		if (a->used <= chars) {
+			if (a->alloced <= chars) {
+				a->alloced = chars + 1;
+				a->chars = realloc(a->chars, a->alloced * sizeof(*(a->chars)));
+			}
+			memset(a->chars + a->used, 0, (chars - a->used + 1) * sizeof(*(a->chars)));
+		}
+	}
+
+	if (action > 0) {
+		a->chars[chars] |= x;
+		return;
+	} else if (action < 0) {
+		a->chars[chars] ^= x;
+	} else if (a->used > chars) {
+		a->chars[chars] &= ~x;
+	}
+
+	while (a->used && !a->chars[a->used - 1])
+		a->used--;
+	if (!a->used)
+		SET_SIGNUM(a, 0);
+}