X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/d34decd2b2b88240cf4ca68a2a5feb7bf36de6e7..3884054be9261b4607f5f3a2d0b79695f65b851f:/mp-arith.c

diff --git a/mp-arith.c b/mp-arith.c
index fe6a45d..d6d892b 100644
--- a/mp-arith.c
+++ b/mp-arith.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mp-arith.c,v 1.6 2000/06/17 11:45:09 mdw Exp $
+ * $Id: mp-arith.c,v 1.10 2001/04/03 19:36:05 mdw Exp $
  *
  * Basic arithmetic on multiprecision integers
  *
@@ -30,6 +30,20 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mp-arith.c,v $
+ * Revision 1.10  2001/04/03 19:36:05  mdw
+ * Add some simple bitwise operations so that Perl can use them.
+ *
+ * Revision 1.9  2000/10/08 15:48:35  mdw
+ * Rename Karatsuba constants now that we have @gfx_kmul@ too.
+ *
+ * Revision 1.8  2000/10/08 12:02:21  mdw
+ * Use @MP_EQ@ instead of @MP_CMP@.
+ *
+ * Revision 1.7  2000/06/22 19:02:53  mdw
+ * New function @mp_odd@ to extract powers of two from an integer.  This is
+ * common code from the Rabin-Miller test, RSA key recovery and modular
+ * square-root extraction.
+ *
  * Revision 1.6  2000/06/17 11:45:09  mdw
  * Major memory management overhaul.  Added arena support.  Use the secure
  * arena for secret integers.  Replace and improve the MP management macros
@@ -138,6 +152,15 @@ mp *mp_lsr(mp *d, mp *a, size_t n)
   return (d);
 }
 
+/* --- @mp_eq@ --- *
+ *
+ * Arguments:	@const mp *a, *b@ = two numbers
+ *
+ * Returns:	Nonzero if the numbers are equal.
+ */
+
+int mp_eq(const mp *a, const mp *b) { return (MP_EQ(a, b)); }
+
 /* --- @mp_cmp@ --- *
  *
  * Arguments:	@const mp *a, *b@ = two numbers
@@ -156,6 +179,38 @@ int mp_cmp(const mp *a, const mp *b)
     return (+1);
 }
 
+/* --- @mpx_and@, @mpx_or@, @mpx_xor@, @mpx_not@ --- *
+ *
+ * Arguments:	@mp *d@ = destination
+ *		@mp *a, *b@ = sources
+ *
+ * Returns:	The result of the obvious bitwise operation.
+ */
+
+#define MP_BITBINOP(name)						\
+									\
+mp *mp_##name(mp *d, mp *a, mp *b)					\
+{									\
+  MP_DEST(d, MAX(MP_LEN(a), MP_LEN(b)), a->f | b->f);			\
+  mpx_##name(d->v, d->vl, a->v, a->vl, b->v, b->vl);			\
+  d->f = (a->f | b->f) & MP_BURN;					\
+  MP_SHRINK(d);								\
+  return (d);								\
+}
+
+MP_BITBINOP(and)
+MP_BITBINOP(or)
+MP_BITBINOP(xor)
+
+mp *mp_not(mp *d, mp *a)
+{
+  MP_DEST(d, MP_LEN(a), a->f);
+  mpx_not(d->v, d->vl, a->v, a->vl);
+  d->f = a->f & MP_BURN;
+  MP_SHRINK(d);
+  return (d);
+}
+
 /* --- @mp_add@ --- *
  *
  * Arguments:	@mp *d@ = destination
@@ -219,14 +274,14 @@ mp *mp_mul(mp *d, mp *a, mp *b)
   a = MP_COPY(a);
   b = MP_COPY(b);
 
-  if (MP_LEN(a) <= KARATSUBA_CUTOFF || MP_LEN(b) <= KARATSUBA_CUTOFF) {
+  if (MP_LEN(a) <= MPK_THRESH || MP_LEN(b) <= MPK_THRESH) {
     MP_DEST(d, MP_LEN(a) + MP_LEN(b), a->f | b->f | MP_UNDEF);
     mpx_umul(d->v, d->vl, a->v, a->vl, b->v, b->vl);
   } else {
     size_t m = 2 * MAX(MP_LEN(a), MP_LEN(b)) + 2;
     mpw *s;
     MP_DEST(d, m, a->f | b->f | MP_UNDEF);
-    m += KARATSUBA_SLOP;
+    m += MPK_SLOP;
     s = mpalloc(d->a, m);
     mpx_kmul(d->v, d->vl, a->v, a->vl, b->v, b->vl, s, s + m);
     mpfree(d->a, s);
@@ -253,9 +308,9 @@ mp *mp_sqr(mp *d, mp *a)
 
   a = MP_COPY(a);
   MP_DEST(d, 2 * m + 2, a->f | MP_UNDEF);
-  if (m > KARATSUBA_CUTOFF) {
+  if (m > MPK_THRESH) {
     mpw *s;
-    m = 2 * (m + 1) + KARATSUBA_SLOP;
+    m = 2 * (m + 1) + MPK_SLOP;
     s = mpalloc(d->a, m);
     mpx_ksqr(d->v, d->vl, a->v, a->vl, s, s + m);
     mpfree(d->a, s);
@@ -364,13 +419,56 @@ void mp_div(mp **qq, mp **rr, mp *a, mp *b)
   }
 }
 
+/* --- @mp_odd@ --- *
+ *
+ * Arguments:	@mp *d@ = pointer to destination integer
+ *		@mp *m@ = pointer to source integer
+ *		@size_t *s@ = where to store the power of 2
+ *
+ * Returns:	An odd integer integer %$t$% such that %$m = 2^s t$%.
+ *
+ * Use:		Computes a power of two and an odd integer which, when
+ *		multiplied, give a specified result.  This sort of thing is
+ *		useful in number theory quite often.
+ */
+
+mp *mp_odd(mp *d, mp *m, size_t *s)
+{
+  size_t ss = 0;
+  const mpw *v, *vl;
+
+  v = m->v;
+  vl = m->vl;
+  for (; !*v && v < vl; v++)
+    ss += MPW_BITS;
+  if (v >= vl)
+    ss = 0;
+  else {
+    mpw x = *v;
+    mpw mask = MPW_MAX;
+    unsigned z = MPW_BITS / 2;
+
+    while (z) {
+      mask >>= z;
+      if (!(x & mask)) {
+	x >>= z;
+	ss += z;
+      }
+      z >>= 1;
+    }
+  }
+
+  *s = ss;
+  return (mp_lsr(d, m, ss));
+}
+
 /*----- Test rig ----------------------------------------------------------*/
 
 #ifdef TEST_RIG
 
 static int verify(const char *op, mp *expect, mp *result, mp *a, mp *b)
 {
-  if (MP_CMP(expect, !=, result)) {
+  if (!MP_EQ(expect, result)) {
     fprintf(stderr, "\n*** %s failed", op);
     fputs("\n*** a      = ", stderr); mp_writefile(a, stderr, 10);
     fputs("\n*** b      = ", stderr); mp_writefile(b, stderr, 10);
@@ -438,6 +536,31 @@ static int tdiv(dstr *v)
   return (ok);
 }
 
+static int todd(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  size_t rs = *(uint32 *)v[1].buf;
+  mp *rt = *(mp **)v[2].buf;
+  int ok = 1;
+  mp *t;
+  size_t s;
+  t = mp_odd(MP_NEW, a, &s);
+  if (s != rs || !MP_EQ(t, rt)) {
+    ok = 0;
+    fprintf(stderr, "\n*** odd failed");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 10);
+    fprintf(stderr, "\n*** s  = %lu", (unsigned long)s);
+    fputs("\n*** t  = ", stderr); mp_writefile(t, stderr, 10);
+    fprintf(stderr, "\n*** rs = %lu", (unsigned long)rs);
+    fputs("\n*** rt = ", stderr); mp_writefile(rt, stderr, 10);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(rt);
+  mp_drop(t);
+  return (ok);
+}
+
 static test_chunk tests[] = {
   { "lsl", tlsl, { &type_mp, &type_mp, &type_mp, 0 } },
   { "lsr", tlsr, { &type_mp, &type_mp, &type_mp, 0 } },
@@ -445,6 +568,7 @@ static test_chunk tests[] = {
   { "sub", tsub, { &type_mp, &type_mp, &type_mp, 0 } },
   { "mul", tmul, { &type_mp, &type_mp, &type_mp, 0 } },
   { "div", tdiv, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
+  { "odd", todd, { &type_mp, &type_uint32, &type_mp, 0 } },
   { 0, 0, { 0 } },
 };