summaryrefslogtreecommitdiffstats
path: root/contrib/libgmp/mpz/ui_pow_ui.c
diff options
context:
space:
mode:
Diffstat (limited to 'contrib/libgmp/mpz/ui_pow_ui.c')
-rw-r--r--contrib/libgmp/mpz/ui_pow_ui.c111
1 files changed, 111 insertions, 0 deletions
diff --git a/contrib/libgmp/mpz/ui_pow_ui.c b/contrib/libgmp/mpz/ui_pow_ui.c
new file mode 100644
index 0000000..19baca1
--- /dev/null
+++ b/contrib/libgmp/mpz/ui_pow_ui.c
@@ -0,0 +1,111 @@
+/* mpz_ui_pow_ui(res, base, exp) -- Set RES to BASE**EXP.
+
+Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+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.
+
+The GNU MP Library 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 the GNU MP Library; see the file COPYING.LIB. If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+void
+#if __STDC__
+mpz_ui_pow_ui (mpz_ptr r, unsigned long int b, unsigned long int e)
+#else
+mpz_ui_pow_ui (r, b, e)
+ mpz_ptr r;
+ unsigned long int b;
+ unsigned long int e;
+#endif
+{
+ mp_ptr rp, tp, xp;
+ mp_size_t rsize;
+ int cnt, i;
+ mp_limb_t blimb = b;
+ TMP_DECL (marker);
+
+ /* Single out cases that give result == 0 or 1. These tests are here
+ to simplify the general code below, not to optimize. */
+ if (e == 0)
+ {
+ r->_mp_d[0] = 1;
+ r->_mp_size = 1;
+ return;
+ }
+ if (blimb == 0)
+ {
+ r->_mp_size = 0;
+ return;
+ }
+
+ if (blimb < 0x100)
+ {
+ /* Estimate space requirements accurately. Using the code from the
+ `else' path would over-estimate space requirements wildly. */
+ float lb = __mp_bases[blimb].chars_per_bit_exactly;
+ rsize = 2 + ((mp_size_t) (e / lb) / BITS_PER_MP_LIMB);
+ }
+ else
+ {
+ /* Over-estimate space requirements somewhat. */
+ count_leading_zeros (cnt, blimb);
+ rsize = e - cnt * e / BITS_PER_MP_LIMB + 1;
+ }
+
+ TMP_MARK (marker);
+
+ /* The two areas are used to alternatingly hold the input and recieve the
+ product for mpn_mul. (This scheme is used to fulfill the requirements
+ of mpn_mul; that the product space may not be the same as any of the
+ input operands.) */
+ rp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB);
+ tp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB);
+
+ rp[0] = blimb;
+ rsize = 1;
+ count_leading_zeros (cnt, e);
+
+ for (i = BITS_PER_MP_LIMB - cnt - 2; i >= 0; i--)
+ {
+ mpn_mul_n (tp, rp, rp, rsize);
+ rsize = 2 * rsize;
+ rsize -= tp[rsize - 1] == 0;
+ xp = tp; tp = rp; rp = xp;
+
+ if ((e & ((mp_limb_t) 1 << i)) != 0)
+ {
+ mp_limb_t cy;
+ cy = mpn_mul_1 (tp, rp, rsize, blimb);
+ if (cy != 0)
+ {
+ tp[rsize] = cy;
+ rsize++;
+ }
+ xp = tp; tp = rp; rp = xp;
+ }
+ }
+
+ /* Now then we know the exact space requirements, reallocate if
+ necessary. */
+ if (r->_mp_alloc < rsize)
+ _mpz_realloc (r, rsize);
+
+ MPN_COPY (r->_mp_d, rp, rsize);
+ r->_mp_size = rsize;
+ TMP_FREE (marker);
+}
OpenPOWER on IntegriCloud