--- /dev/null
+/* Mulder's MulHigh function (short product)
+
+Copyright 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 2.1 of the License, or (at your
+option) any later version.
+
+The GNU MPFR 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 MPFR Library; see the file COPYING.LIB. If not, write to
+the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+MA 02110-1301, USA. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+#ifndef MUL_FFT_THRESHOLD
+#define MUL_FFT_THRESHOLD 8448
+#endif
+
+/* Don't use MPFR_MULHIGH_SIZE since it is handled by tuneup */
+#ifdef MPFR_MULHIGH_TAB_SIZE
+static short mulhigh_ktab[MPFR_MULHIGH_TAB_SIZE];
+#else
+static short mulhigh_ktab[] = {MPFR_MULHIGH_TAB};
+#define MPFR_MULHIGH_TAB_SIZE \
+ ((mp_size_t) (sizeof(mulhigh_ktab) / sizeof(mulhigh_ktab[0])))
+#endif
+
+/* Put in rp[n..2n-1] an approximation of the n high limbs
+ of {mp, n} * {np, n}.
+ The error is at worst of ln(n) for rp[n] and rp[n-1] is totally wrong */
+static void
+mpfr_mulhigh_n_basecase (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
+{
+ mp_size_t i;
+
+ rp += n-1;
+ umul_ppmm (rp[1], rp[0], up[n-1], vp[0]);
+ for (i = 1 ; i < n ; i++)
+ rp[i+1] = mpn_addmul_1 (rp, up + (n - i - 1), i+1, vp[i]);
+}
+
+void
+mpfr_mulhigh_n (mp_ptr rp, mp_srcptr np, mp_srcptr mp, mp_size_t n)
+{
+ mp_size_t k;
+
+ MPFR_ASSERTD (MPFR_MULHIGH_TAB_SIZE > 4);
+ k = MPFR_LIKELY (n < MPFR_MULHIGH_TAB_SIZE) ? mulhigh_ktab[n] : 2*n/3;
+ MPFR_ASSERTD (k == -1 || k == 0 || (k > n/2 && k < n));
+ if (k < 0)
+ mpn_mul_basecase (rp, np, n, mp, n);
+ else if (k == 0)
+ mpfr_mulhigh_n_basecase (rp, np, mp, n);
+ else if (n > MUL_FFT_THRESHOLD)
+ mpn_mul_n (rp, np, mp, n);
+ else
+ {
+ mp_size_t l = n - k;
+ mp_limb_t cy;
+
+ mpn_mul_n (rp + 2 * l, np + l, mp + l, k); /* fills rp[2l..2n-1] */
+ mpfr_mulhigh_n (rp, np + k, mp, l); /* fills rp[l-1..2l-1] */
+ cy = mpn_add_n (rp + n - 1, rp + n - 1, rp + l - 1, l + 1);
+ mpfr_mulhigh_n (rp, np, mp + k, l); /* fills rp[l-1..2l-1] */
+ cy += mpn_add_n (rp + n - 1, rp + n - 1, rp + l - 1, l + 1);
+ mpn_add_1 (rp + n + l, rp + n + l, k, cy); /* propagate carry */
+ }
+}
+
+#ifdef MPFR_SQRHIGH_TAB_SIZE
+static short sqrhigh_ktab[MPFR_SQRHIGH_TAB_SIZE];
+#else
+static short sqrhigh_ktab[] = {MPFR_SQRHIGH_TAB};
+#define MPFR_SQRHIGH_TAB_SIZE (sizeof(sqrhigh_ktab) / sizeof(sqrhigh_ktab[0]))
+#endif
+
+void
+mpfr_sqrhigh_n (mp_ptr rp, mp_srcptr np, mp_size_t n)
+{
+ mp_size_t k;
+
+ MPFR_ASSERTD (MPFR_SQRHIGH_TAB_SIZE > 4);
+ k = MPFR_LIKELY (n < MPFR_SQRHIGH_TAB_SIZE) ? sqrhigh_ktab[n] : 2*n/3;
+ MPFR_ASSERTD (k == -1 || k == 0 || (k > n/2 && k < n));
+ if (k < 0)
+ /* we can't use mpn_sqr_basecase here, since it requires
+ n <= SQR_KARATSUBA_THRESHOLD, where SQR_KARATSUBA_THRESHOLD
+ is not exported by GMP */
+ mpn_sqr_n (rp, np, n);
+ else if (k == 0)
+ mpfr_mulhigh_n_basecase (rp, np, np, n);
+ else
+ {
+ mp_size_t l = n - k;
+ mp_limb_t cy;
+
+ mpn_sqr_n (rp + 2 * l, np + l, k); /* fills rp[2l..2n-1] */
+ mpfr_mulhigh_n (rp, np, np + k, l); /* fills rp[l-1..2l-1] */
+ /* FIXME: maybe shift by 2 is a better idea but it has to handle carry*/
+ cy = mpn_add_n (rp + n - 1, rp + n - 1, rp + l - 1, l + 1);
+ cy += mpn_add_n (rp + n - 1, rp + n - 1, rp + l - 1, l + 1);
+ mpn_add_1 (rp + n + l, rp + n + l, k, cy); /* propagate carry */
+ }
+}
projects / msp430-gcc.git / blobdiff