Bit setting and clearing functions.

[u/mdw/catacomb] / mp-arith.c

diff --git a/mp-arith.c b/mp-arith.c
index 23137e2..e47f301 100644 (file)
--- a/mp-arith.c
+++ b/mp-arith.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mp-arith.c,v 1.12 2002/10/09 00:36:03 mdw Exp $
+ * $Id: mp-arith.c,v 1.13 2002/10/15 00:19:40 mdw Exp $
  *
  * Basic arithmetic on multiprecision integers
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mp-arith.c,v $
+ * Revision 1.13  2002/10/15 00:19:40  mdw
+ * Bit setting and clearing functions.
+ *
  * Revision 1.12  2002/10/09 00:36:03  mdw
  * Fix bounds on workspace for Karatsuba operations.
  *
@@ -142,34 +145,31 @@ mp *mp_lsr2c(mp *d, mp *a, size_t n)
 /* --- @mp_testbit@ --- *
  *
  * Arguments:  @mp *x@ = a large integer
- *             @size_t n@ = which bit to test
+ *             @unsigned long n@ = which bit to test
  *
  * Returns:    Nonzero if the bit is set, zero if not.
  */
 
-int mp_testbit(mp *x, size_t n)
+int mp_testbit(mp *x, unsigned long n)
 {
-  size_t o;
   if (n > MPW_BITS * MP_LEN(x))
     return (0);
-  o = n / MPW_BITS;
-  n %= MPW_BITS;
-  return ((x->v[o] >> n) & 1);
+  return ((x->v[n/MPW_BITS] >> n%MPW_BITS) & 1u);
 }
 
 /* --- @mp_testbit2c@ --- *
  *
  * Arguments:  @mp *x@ = a large integer
- *             @size_t n@ = which bit to test
+ *             @unsigned long n@ = which bit to test
  *
  * Returns:    Nonzero if the bit is set, zero if not.  Fakes up two's
  *             complement representation.
  */
 
-int mp_testbit2c(mp *x, size_t n)
+int mp_testbit2c(mp *x, unsigned long n)
 {
   int r;
-  if (x->f & MP_NEG)
+  if (!(x->f & MP_NEG))
     return (mp_testbit(x, n));
   x = mp_not2c(MP_NEW, x);
   r = !mp_testbit(x, n);
@@ -177,6 +177,73 @@ int mp_testbit2c(mp *x, size_t n)
   return (r);
 }
 
+/* --- @mp_setbit@, @mp_clearbit@ --- *
+ *
+ * Arguments:  @mp *d@ = a destination
+ *             @mp *x@ = a large integer
+ *             @unsigned long n@ = which bit to modify
+ *
+ * Returns:    The argument @x@, with the appropriate bit set or cleared.
+ */
+
+mp *mp_setbit(mp *d, mp *x, unsigned long n)
+{
+  size_t rq;
+
+  rq = n + MPW_BITS; rq -= rq % MPW_BITS;
+  if (d != x) {
+    if (d) MP_DROP(d);
+    d = MP_COPY(x);
+  }
+  MP_DEST(d, rq, x->f & (MP_NEG | MP_BURN));
+  d->v[n/MPW_BITS] |= 1 << n%MPW_BITS;
+  return (d);
+}
+
+mp *mp_clearbit(mp *d, mp *x, unsigned long n)
+{
+  size_t rq;
+
+  rq = n + MPW_BITS; rq -= rq % MPW_BITS;
+  if (d != x) {
+    if (d) MP_DROP(d);
+    d = MP_COPY(x);
+  }
+  MP_DEST(d, rq, x->f & (MP_NEG | MP_BURN));
+  d->v[n/MPW_BITS] &= ~(1 << n%MPW_BITS);
+  return (d);
+}
+
+/* --- @mp_setbit2c@, @mp_clearbit2c@ --- *
+ *
+ * Arguments:  @mp *d@ = a destination
+ *             @mp *x@ = a large integer
+ *             @unsigned long n@ = which bit to modify
+ *
+ * Returns:    The argument @x@, with the appropriate bit set or cleared.
+ *             Fakes up two's complement representation.
+ */
+
+mp *mp_setbit2c(mp *d, mp *x, unsigned long n)
+{
+  if (!(x->f & MP_NEG))
+    return mp_setbit(d, x, n);
+  d = mp_not2c(d, x);
+  d = mp_clearbit(d, d, n);
+  d = mp_not2c(d, d);
+  return (d);
+}
+
+mp *mp_clearbit2c(mp *d, mp *x, unsigned long n)
+{
+  if (!(x->f & MP_NEG))
+    return mp_clearbit(d, x, n);
+  d = mp_not2c(d, x);
+  d = mp_setbit(d, d, n);
+  d = mp_not2c(d, d);
+  return (d);
+}
+
 /* --- @mp_eq@ --- *
  *
  * Arguments:  @const mp *a, *b@ = two numbers
@@ -719,6 +786,70 @@ MPX_DOBIN(DO)
   return (ok);
 }
 
+static int tset(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  unsigned long n = *(unsigned long *)v[1].buf;
+  mp *r = *(mp **)v[2].buf;
+  mp *c;
+  int ok = 1;
+
+  c = mp_setbit2c(MP_NEW, a, n);
+  if (!MP_EQ(c, r)) {
+    ok = 0;
+    fprintf(stderr, "\n***setbit (set) failed");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 16);
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputs("\n*** c = ", stderr); mp_writefile(c, stderr, 16);
+    fputc('\n', stderr);
+  }
+  if (!mp_testbit2c(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n***setbit (test) failed");
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(r);
+  mp_drop(c);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);
+}
+
+static int tclr(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  unsigned long n = *(unsigned long *)v[1].buf;
+  mp *r = *(mp **)v[2].buf;
+  mp *c;
+  int ok = 1;
+
+  c = mp_clearbit2c(MP_NEW, a, n);
+  if (!MP_EQ(c, r)) {
+    ok = 0;
+    fprintf(stderr, "\n***clrbit (set) failed");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 16);
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputs("\n*** c = ", stderr); mp_writefile(c, stderr, 16);
+    fputc('\n', stderr);
+  }
+  if (mp_testbit2c(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n***clrbit (test) failed");
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(c);
+  mp_drop(r);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);
+}
+
 static int todd(dstr *v)
 {
   mp *a = *(mp **)v[0].buf;
@@ -741,6 +872,7 @@ static int todd(dstr *v)
   mp_drop(a);
   mp_drop(rt);
   mp_drop(t);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }
 
@@ -749,6 +881,8 @@ static test_chunk tests[] = {
   { "lsr", tlsr, { &type_mp, &type_int, &type_mp, 0 } },
   { "lsl2c", tlsl2c, { &type_mp, &type_int, &type_mp, 0 } },
   { "lsr2c", tlsr2c, { &type_mp, &type_int, &type_mp, 0 } },
+  { "setbit", tset, { &type_mp, &type_ulong, &type_mp, 0 } },
+  { "clrbit", tclr, { &type_mp, &type_ulong, &type_mp, 0 } },
   { "add", tadd, { &type_mp, &type_mp, &type_mp, 0 } },
   { "sub", tsub, { &type_mp, &type_mp, &type_mp, 0 } },
   { "mul", tmul, { &type_mp, &type_mp, &type_mp, 0 } },