--- /dev/null
+/* UltraSPARC 64 mpn_mod_1 -- mpn by limb remainder.
+
+Copyright 1991, 1993, 1994, 1999, 2000, 2001, 2003 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 Lesser General Public License as published by
+the Free Software Foundation; either version 3 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+#include "mpn/sparc64/sparc64.h"
+
+
+/* 64-bit divisor 32-bit divisor
+ cycles/limb cycles/limb
+ (approx) (approx)
+ Ultrasparc 2i: 160 120
+*/
+
+
+/* 32-bit divisors are treated in special case code. This requires 4 mulx
+ per limb instead of 8 in the general case.
+
+ For big endian systems we need HALF_ENDIAN_ADJ included in the src[i]
+ addressing, to get the two halves of each limb read in the correct order.
+ This is kept in an adj variable. Doing that measures about 6 c/l faster
+ than just writing HALF_ENDIAN_ADJ(i) in the loop. The latter shouldn't
+ be 6 cycles worth of work, but perhaps it doesn't schedule well (on gcc
+ 3.2.1 at least).
+
+ A simple udivx/umulx loop for the 32-bit case was attempted for small
+ sizes, but at size==2 it was only about the same speed and at size==3 was
+ slower. */
+
+mp_limb_t
+mpn_mod_1 (mp_srcptr src_limbptr, mp_size_t size_limbs, mp_limb_t d_limb)
+{
+ int norm, norm_rshift;
+ mp_limb_t src_high_limb;
+ mp_size_t i;
+
+ ASSERT (size_limbs >= 0);
+ ASSERT (d_limb != 0);
+
+ if (UNLIKELY (size_limbs == 0))
+ return 0;
+
+ src_high_limb = src_limbptr[size_limbs-1];
+
+ /* udivx is good for size==1, and no need to bother checking limb<divisor,
+ since if that's likely the caller should check */
+ if (UNLIKELY (size_limbs == 1))
+ return src_high_limb % d_limb;
+
+ if (d_limb <= CNST_LIMB(0xFFFFFFFF))
+ {
+ unsigned *src, n1, n0, r, dummy_q, nshift, norm_rmask;
+ mp_size_t size, adj;
+ mp_limb_t dinv_limb;
+
+ size = 2 * size_limbs; /* halfwords */
+ src = (unsigned *) src_limbptr;
+
+ /* prospective initial remainder, if < d */
+ r = src_high_limb >> 32;
+
+ /* If the length of the source is uniformly distributed, then there's
+ a 50% chance of the high 32-bits being zero, which we can skip. */
+ if (r == 0)
+ {
+ r = (unsigned) src_high_limb;
+ size--;
+ ASSERT (size > 0); /* because always even */
+ }
+
+ /* Skip a division if high < divisor. Having the test here before
+ normalizing will still skip as often as possible. */
+ if (r < d_limb)
+ {
+ size--;
+ ASSERT (size > 0); /* because size==1 handled above */
+ }
+ else
+ r = 0;
+
+ count_leading_zeros_32 (norm, d_limb);
+ norm -= 32;
+ d_limb <<= norm;
+
+ norm_rshift = 32 - norm;
+ norm_rmask = (norm == 0 ? 0 : 0xFFFFFFFF);
+ i = size-1;
+ adj = HALF_ENDIAN_ADJ (i);
+ n1 = src [i + adj];
+ r = (r << norm) | ((n1 >> norm_rshift) & norm_rmask);
+
+ invert_half_limb (dinv_limb, d_limb);
+ adj = -adj;
+
+ for (i--; i >= 0; i--)
+ {
+ n0 = src [i + adj];
+ adj = -adj;
+ nshift = (n1 << norm) | ((n0 >> norm_rshift) & norm_rmask);
+ udiv_qrnnd_half_preinv (dummy_q, r, r, nshift, d_limb, dinv_limb);
+ n1 = n0;
+ }
+
+ /* same as loop, but without n0 */
+ nshift = n1 << norm;
+ udiv_qrnnd_half_preinv (dummy_q, r, r, nshift, d_limb, dinv_limb);
+
+ ASSERT ((r & ((1 << norm) - 1)) == 0);
+ return r >> norm;
+ }
+ else
+ {
+ mp_srcptr src;
+ mp_size_t size;
+ mp_limb_t n1, n0, r, dinv, dummy_q, nshift, norm_rmask;
+
+ src = src_limbptr;
+ size = size_limbs;
+ r = src_high_limb; /* initial remainder */
+
+ /* Skip a division if high < divisor. Having the test here before
+ normalizing will still skip as often as possible. */
+ if (r < d_limb)
+ {
+ size--;
+ ASSERT (size > 0); /* because size==1 handled above */
+ }
+ else
+ r = 0;
+
+ count_leading_zeros (norm, d_limb);
+ d_limb <<= norm;
+
+ norm_rshift = GMP_LIMB_BITS - norm;
+ norm_rmask = (norm == 0 ? 0 : 0xFFFFFFFF);
+
+ src += size;
+ n1 = *--src;
+ r = (r << norm) | ((n1 >> norm_rshift) & norm_rmask);
+
+ invert_limb (dinv, d_limb);
+
+ for (i = size-2; i >= 0; i--)
+ {
+ n0 = *--src;
+ nshift = (n1 << norm) | ((n0 >> norm_rshift) & norm_rmask);
+ udiv_qrnnd_preinv (dummy_q, r, r, nshift, d_limb, dinv);
+ n1 = n0;
+ }
+
+ /* same as loop, but without n0 */
+ nshift = n1 << norm;
+ udiv_qrnnd_preinv (dummy_q, r, r, nshift, d_limb, dinv);
+
+ ASSERT ((r & ((CNST_LIMB(1) << norm) - 1)) == 0);
+ return r >> norm;
+ }
+}
projects / msp430-gcc.git / blobdiff