/* -*-c-*-
*
- * $Id: mp-arith.c,v 1.6 2000/06/17 11:45:09 mdw Exp $
+ * $Id: mp-arith.c,v 1.8 2000/10/08 12:02:21 mdw Exp $
*
* Basic arithmetic on multiprecision integers
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mp-arith.c,v $
+ * 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
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
}
}
+/* --- @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);
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 } },
{ "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 } },
};