add bitstring

1999-09-07 01:32:27 +00:00
parent 6ac145533e
commit 1819606910
4 changed files with 243 additions and 8 deletions
--- a/lib/isc/bitstring.c
+++ b/lib/isc/bitstring.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 1999  Internet Software Consortium.
+ * 
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
+ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
+ * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <stddef.h>
+
+#include <isc/types.h>
+#include <isc/assertions.h>
+#include <isc/bitstring.h>
+
+#define DIV8(x)			((x) >> 3)
+#define MOD8(x)			((x) & 0x00000007U)
+#define OCTETS(n)		((n + 7) >> 3)
+#define PADDED(n)		(((n + 7) >> 3) << 3)
+#define BITSET(bs, n) 		(((bs)->data[DIV8(n)] & \
+				 (1 << (7 - MOD8(n)))) != 0)
+#define SETBIT(bs, n)		(bs)->data[DIV8(n)] |= (1 << (7 - MOD8(n)))
+#define CLEARBIT(bs, n)		(bs)->data[DIV8(n)] &= ~(1 << (7 - MOD8(n)))
+
+#define BITSTRING_MAGIC			0x42537472U	/* BStr. */
+#define VALID_BITSTRING(b)		((b) != NULL && \
+					 (b)->magic == BITSTRING_MAGIC)
+
+void
+isc_bitstring_init(isc_bitstring_t *bitstring, unsigned char *data,
+		   unsigned int length, unsigned int size, isc_boolean_t lsb0)
+{
+	/*
+	 * Make 'bitstring' refer to the bitstring of 'size' bits starting
+	 * at 'data'.  'length' bits of the bitstring are valid.  If 'lsb0'
+	 * is set then, bit 0 refers to the least significant bit of the
+	 * bitstring.  Otherwise bit 0 is the most significant bit.
+	 */
+
+	REQUIRE(bitstring != NULL);
+	REQUIRE(data != NULL);
+	REQUIRE(length <= size);
+
+	bitstring->magic = BITSTRING_MAGIC;
+	bitstring->data = data;
+	bitstring->length = length;
+	bitstring->size = size;
+	bitstring->lsb0 = lsb0;
+}
+
+void
+isc_bitstring_invalidate(isc_bitstring_t *bitstring) {
+
+	/*
+	 * Invalidate 'bitstring'.
+	 */
+
+	REQUIRE(VALID_BITSTRING(bitstring));
+
+	bitstring->magic = 0;
+	bitstring->data = NULL;
+	bitstring->length = 0;
+	bitstring->size = 0;
+	bitstring->lsb0 = ISC_FALSE;
+}
+
+void
+isc_bitstring_copy(isc_bitstring_t *source, unsigned int sbitpos,
+		   isc_bitstring_t *target, unsigned int tbitpos,
+		   unsigned int n)
+{
+	unsigned int tlast;
+
+	/*
+	 * Starting at bit 'sbitpos', copy 'n' bits from 'source' to
+	 * the 'n' bits of 'target' starting at 'tbitpos'.
+	 */
+
+	REQUIRE(VALID_BITSTRING(source));
+	REQUIRE(VALID_BITSTRING(target));
+	if (source->lsb0) {
+		REQUIRE(sbitpos < source->length);
+		sbitpos = PADDED(source->size) - sbitpos - 1;
+		REQUIRE(sbitpos >= n - 1);
+		sbitpos -= n - 1;
+	} else
+		REQUIRE(sbitpos + n <= source->length);
+	tlast = tbitpos + n;
+	if (target->lsb0) {
+		REQUIRE(tbitpos <= target->length);
+		tbitpos = PADDED(target->size) - tbitpos - 1;
+		REQUIRE(tbitpos >= n - 1);
+		tbitpos -= n - 1;
+	} else		
+		REQUIRE(tlast<= target->size);
+
+	if (tlast > target->length)
+		target->length = tlast;
+
+	/*
+	 * This is far from optimal...
+	 */
+
+	while (n > 0) {
+		if (BITSET(source, sbitpos))
+			SETBIT(target, tbitpos);
+		else
+			CLEARBIT(target, tbitpos);
+		sbitpos++;
+		tbitpos++;
+		n--;
+	}
+}