/* -*-c-*-
*
- * $Id: mp-arith.c,v 1.15 2002/10/19 17:56:50 mdw Exp $
+ * $Id: mp-arith.c,v 1.17 2003/10/12 15:03:35 mdw Exp $
*
* Basic arithmetic on multiprecision integers
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mp-arith.c,v $
+ * Revision 1.17 2003/10/12 15:03:35 mdw
+ * Merge fix from other branch.
+ *
+ * Revision 1.16.2.1 2003/06/10 13:21:10 mdw
+ * Fix bug dividing small things by large ones.
+ *
+ * Revision 1.16 2003/05/16 09:09:24 mdw
+ * Fix @mp_lsl2c@. Turns out to be surprisingly tricky.
+ *
* Revision 1.15 2002/10/19 17:56:50 mdw
* Fix bit operations. Test them (a bit) better.
*
/*----- Main code ---------------------------------------------------------*/
-/* --- @mp_lsl@, @mp_lsr@ --- *
+/* --- @mp_lsl@, @mp_lslc@, @mp_lsr@ --- *
*
* Arguments: @mp *d@ = destination
* @mp *a@ = source
* @size_t n@ = number of bits to move
*
* Returns: Result, @a@ shifted left or right by @n@.
+ *
+ * Use: Bitwise shift operators. @mp_lslc@ fills the bits introduced
+ * on the right with ones instead of zeroes: it's used
+ * internally by @mp_lsl2c@, though it may be useful on its
+ * own.
*/
mp *mp_lsl(mp *d, mp *a, size_t n)
return (d);
}
+mp *mp_lslc(mp *d, mp *a, size_t n)
+{
+ MP_DEST(d, MP_LEN(a) + (n + MPW_BITS - 1) / MPW_BITS, a->f);
+ mpx_lslc(d->v, d->vl, a->v, a->vl, n);
+ d->f = a->f & (MP_NEG | MP_BURN);
+ MP_SHRINK(d);
+ return (d);
+}
+
mp *mp_lsr(mp *d, mp *a, size_t n)
{
MP_DEST(d, MP_LEN(a), a->f);
if (!(a->f & MP_NEG))
return (mp_lsl(d, a, n));
d = mp_not2c(d, a);
- d = mp_lsl(d, d, n);
+ d = mp_lslc(d, d, n);
d = mp_not2c(d, d);
return (d);
}
MP_SHRINK(a);
MP_COPY(a);
- if (d) MP_DROP(d);
- if (a->v == a->vl) {
+ if (d)
+ MP_DROP(d);
+ if (a->v == a->vl)
return (a);
- }
MP_DEST(a, MP_LEN(a), a->f);
a->f ^= MP_NEG;
return (a);
if (r)
MP_DROP(r);
r = a;
- MP_DEST(r, MP_LEN(a) + 2, a->f | b->f);
+ MP_DEST(r, MAX(MP_LEN(a), MP_LEN(b)) + 2, a->f | b->f);
/* --- Fix up the quotient too --- */