/* -*-c-*-
*
- * $Id: mpscan.h,v 1.1 1999/09/03 08:41:12 mdw Exp $
+ * $Id: mpscan.h,v 1.5 2004/04/08 01:36:15 mdw Exp $
*
* Sequential bit scan of multiprecision integers
*
* (c) 1999 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
- *
+ *
* Catacomb is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
- *
+ *
* You should have received a copy of the GNU Library General Public
* License along with Catacomb; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
-/*----- Revision history --------------------------------------------------*
- *
- * $Log: mpscan.h,v $
- * Revision 1.1 1999/09/03 08:41:12 mdw
- * Initial import.
- *
- */
-
-#ifndef MPSCAN_H
-#define MPSCAN_H
+#ifndef CATACOMB_MPSCAN_H
+#define CATACOMB_MPSCAN_H
#ifdef __cplusplus
extern "C" {
/*----- Header files ------------------------------------------------------*/
-#ifndef MPTYPES_H
-# include "mptypes.h"
+#ifndef CATACOMB_MPW_H
+# include "mpw.h"
#endif
/*----- Data structures ---------------------------------------------------*/
typedef struct mpscan {
- const mpw *v; /* Vector of words to scan */
+ const mpw *v, *vl; /* Vector of words to scan */
mpw w; /* Current word to scan */
int bits; /* Number of bits left in @w@ */
- size_t len; /* Length of the vector in words */
} mpscan;
-/*----- Functions provided ------------------------------------------------*/
+/*----- Right-to-left scanning --------------------------------------------*/
/* --- @mpscan_initx@ --- *
*
* Arguments: @mpscan *m@ = pointer to bitscanner structure
- * @const mpw *v@ = vector of words to scan
- * @size_t len@ = length of vector in words
+ * @const mpw *v, *vl@ = vector of words to scan
*
* Returns: ---
*
- * Use: Initializes a bitscanner from a low-level vector-and-length
+ * Use: Initializes a bitscanner from a low-level base-and-limit
* representation of an integer. Initially no bit is ready; you
* must call @mpscan_step@ before anything useful will come
* out.
*/
-#define MPSCAN_INITX(m_, v_, len_) do { \
+#define MPSCAN_INITX(m_, v_, vl_) do { \
mpscan *_m = (m_); \
_m->v = (v_); \
- _m->len = (len_); \
+ _m->vl = (vl_); \
_m->bits = 0; \
} while (0)
-extern void mpscan_initx(mpscan */*m*/, const mpw */*v*/, size_t /*len*/);
+extern void mpscan_initx(mpscan */*m*/, const mpw */*v*/, const mpw */*vl*/);
/* --- @mpscan_step@ --- *
*
*/
#define MPSCAN_STEP(m) \
- ((m)->bits ? ((m)->w >>= 1, \
- (m)->bits--, 1) : \
- (m)->len ? ((m)->len--, \
- (m)->w = *(m)->v++, \
- (m)->bits = MP_WBITS - 1, 1) : \
+ ((m)->bits ? ((m)->w >>= 1, (m)->bits--, 1) : \
+ (m)->v < (m)->vl ? ((m)->w = *(m)->v++, \
+ (m)->bits = MPW_BITS - 1, 1) : \
0)
extern int mpscan_step(mpscan */*m*/);
extern int mpscan_bit(const mpscan */*m*/);
+/*----- Left-to right-scanning --------------------------------------------*/
+
+/* --- @mpscan_rinitx@ --- *
+ *
+ * Arguments: @mpscan *m@ = pointer to bitscanner structure
+ * @const mpw *v, *vl@ = vector of words to scan
+ *
+ * Returns: ---
+ *
+ * Use: Initializes a reverse bitscanner from a low-level
+ * vector-and-length representation of an integer. Initially no
+ * bit is ready; you must call @mpscan_rstep@ before anything
+ * useful will come out.
+ */
+
+#define MPSCAN_RINITX(m_, v_, vl_) do { \
+ mpscan *_m = (m_); \
+ _m->v = (v_); \
+ _m->vl = (vl_); \
+ while (_m->vl > _m->v && !_m->vl[-1]) \
+ _m->vl--; \
+ _m->bits = 0; \
+} while (0)
+
+extern void mpscan_rinitx(mpscan */*m*/,
+ const mpw */*v*/, const mpw */*vl*/);
+
+/* --- @mpscan_rstep@ --- *
+ *
+ * Arguments: @mpscan *m@ = pointer to bitscanner
+ *
+ * Returns: Nonzero if there is another bit to read.
+ *
+ * Use: Steps on to the next bit in the integer. The macro version
+ * evaluates its argument multiple times.
+ */
+
+#define MPSCAN_RSTEP(m) \
+ ((m)->bits ? ((m)->w <<= 1, (m)->bits--, 1) : \
+ (m)->vl > (m)->v ? ((m)->w = *--(m)->vl, \
+ (m)->bits = MPW_BITS - 1, 1) : \
+ 0)
+
+extern int mpscan_rstep(mpscan */*m*/);
+
+/* --- @mpscan_rbit@ --- *
+ *
+ * Arguments: @const mpscan *m@ = pointer to bitscanner
+ *
+ * Returns: The value of the current bit.
+ *
+ * Use: Reads the value of the current bit looked at by a
+ * reverse bitscanner.
+ */
+
+#define MPSCAN_RBIT(m) (((m)->w >> (MPW_BITS - 1)) & 1)
+
+extern int mpscan_rbit(const mpscan */*m*/);
+
/*----- That's all, folks -------------------------------------------------*/
#ifdef __cplusplus
projects / u / mdw / catacomb / blobdiff