--- /dev/null
+/* mpfr_round_raw_generic, mpfr_round_raw2, mpfr_round_raw, mpfr_prec_round,
+ mpfr_can_round, mpfr_can_round_raw -- various rounding functions
+
+Copyright 1999, 2000, 2001, 2002, 2003, 2004, 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. */
+
+#include "mpfr-impl.h"
+
+#define mpfr_round_raw_generic mpfr_round_raw
+#define flag 0
+#define use_inexp 1
+#include "round_raw_generic.c"
+
+#define mpfr_round_raw_generic mpfr_round_raw_2
+#define flag 1
+#define use_inexp 0
+#include "round_raw_generic.c"
+
+/* Seems to be unused. Remove comment to implement it.
+#define mpfr_round_raw_generic mpfr_round_raw_3
+#define flag 1
+#define use_inexp 1
+#include "round_raw_generic.c"
+*/
+
+#define mpfr_round_raw_generic mpfr_round_raw_4
+#define flag 0
+#define use_inexp 0
+#include "round_raw_generic.c"
+
+int
+mpfr_prec_round (mpfr_ptr x, mp_prec_t prec, mp_rnd_t rnd_mode)
+{
+ mp_limb_t *tmp, *xp;
+ int carry, inexact;
+ mp_prec_t nw, ow;
+ MPFR_TMP_DECL(marker);
+
+ MPFR_ASSERTN(prec >= MPFR_PREC_MIN && prec <= MPFR_PREC_MAX);
+
+ nw = 1 + (prec - 1) / BITS_PER_MP_LIMB; /* needed allocated limbs */
+
+ /* check if x has enough allocated space for the mantissa */
+ ow = MPFR_GET_ALLOC_SIZE(x);
+ if (nw > ow)
+ {
+ /* Realloc mantissa */
+ mp_ptr tmpx = (mp_ptr) (*__gmp_reallocate_func)
+ (MPFR_GET_REAL_PTR(x), MPFR_MALLOC_SIZE(ow), MPFR_MALLOC_SIZE(nw));
+ MPFR_SET_MANT_PTR(x, tmpx); /* mant ptr must be set before alloc size */
+ MPFR_SET_ALLOC_SIZE(x, nw); /* new number of allocated limbs */
+ }
+
+ if (MPFR_UNLIKELY( MPFR_IS_SINGULAR(x) ))
+ {
+ MPFR_PREC(x) = prec; /* Special value: need to set prec */
+ if (MPFR_IS_NAN(x))
+ MPFR_RET_NAN;
+ MPFR_ASSERTD(MPFR_IS_INF(x) || MPFR_IS_ZERO(x));
+ return 0; /* infinity and zero are exact */
+ }
+
+ /* x is a non-zero real number */
+
+ MPFR_TMP_MARK(marker);
+ tmp = (mp_limb_t*) MPFR_TMP_ALLOC (nw * BYTES_PER_MP_LIMB);
+ xp = MPFR_MANT(x);
+ carry = mpfr_round_raw (tmp, xp, MPFR_PREC(x), MPFR_IS_NEG(x),
+ prec, rnd_mode, &inexact);
+ MPFR_PREC(x) = prec;
+
+ if (MPFR_UNLIKELY(carry))
+ {
+ mp_exp_t exp = MPFR_EXP (x);
+
+ if (MPFR_UNLIKELY(exp == __gmpfr_emax))
+ (void) mpfr_overflow(x, rnd_mode, MPFR_SIGN(x));
+ else
+ {
+ MPFR_ASSERTD (exp < __gmpfr_emax);
+ MPFR_SET_EXP (x, exp + 1);
+ xp[nw - 1] = MPFR_LIMB_HIGHBIT;
+ if (nw - 1 > 0)
+ MPN_ZERO(xp, nw - 1);
+ }
+ }
+ else
+ MPN_COPY(xp, tmp, nw);
+
+ MPFR_TMP_FREE(marker);
+ return inexact;
+}
+
+/* assumption: BITS_PER_MP_LIMB is a power of 2 */
+
+/* assuming b is an approximation to x in direction rnd1 with error at
+ most 2^(MPFR_EXP(b)-err), returns 1 if one is able to round exactly
+ x to precision prec with direction rnd2, and 0 otherwise.
+
+ Side effects: none.
+*/
+
+int
+mpfr_can_round (mpfr_srcptr b, mp_exp_t err, mp_rnd_t rnd1,
+ mp_rnd_t rnd2, mp_prec_t prec)
+{
+ if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(b)))
+ return 0; /* We cannot round if Zero, Nan or Inf */
+ else
+ return mpfr_can_round_raw(MPFR_MANT(b), MPFR_LIMB_SIZE(b),
+ MPFR_SIGN(b), err, rnd1, rnd2, prec);
+}
+
+int
+mpfr_can_round_raw (const mp_limb_t *bp, mp_size_t bn, int neg, mp_exp_t err0,
+ mp_rnd_t rnd1, mp_rnd_t rnd2, mp_prec_t prec)
+{
+ mp_prec_t err;
+ mp_size_t k, k1, tn;
+ int s, s1;
+ mp_limb_t cc, cc2;
+ mp_limb_t *tmp;
+ MPFR_TMP_DECL(marker);
+
+ if (MPFR_UNLIKELY(err0 < 0 || (mp_exp_unsigned_t) err0 <= prec))
+ return 0; /* can't round */
+ else if (MPFR_UNLIKELY (prec > (mp_prec_t) bn * BITS_PER_MP_LIMB))
+ { /* then ulp(b) < precision < error */
+ return rnd2 == GMP_RNDN && (mp_exp_unsigned_t) err0 - 2 >= prec;
+ /* can round only in rounding to the nearest and err0 >= prec + 2 */
+ }
+
+ MPFR_ASSERT_SIGN(neg);
+ neg = MPFR_IS_NEG_SIGN(neg);
+
+ /* if the error is smaller than ulp(b), then anyway it will propagate
+ up to ulp(b) */
+ err = ((mp_exp_unsigned_t) err0 > (mp_prec_t) bn * BITS_PER_MP_LIMB) ?
+ (mp_prec_t) bn * BITS_PER_MP_LIMB : (mp_prec_t) err0;
+
+ /* warning: if k = m*BITS_PER_MP_LIMB, consider limb m-1 and not m */
+ k = (err - 1) / BITS_PER_MP_LIMB;
+ MPFR_UNSIGNED_MINUS_MODULO(s, err);
+
+ /* the error corresponds to bit s in limb k, the most significant limb
+ being limb 0 */
+ k1 = (prec - 1) / BITS_PER_MP_LIMB;
+ MPFR_UNSIGNED_MINUS_MODULO(s1, prec);
+
+ /* the last significant bit is bit s1 in limb k1 */
+
+ /* don't need to consider the k1 most significant limbs */
+ k -= k1;
+ bn -= k1;
+ prec -= (mp_prec_t) k1 * BITS_PER_MP_LIMB;
+ /* if when adding or subtracting (1 << s) in bp[bn-1-k], it does not
+ change bp[bn-1] >> s1, then we can round */
+
+ MPFR_TMP_MARK(marker);
+ tn = bn;
+ k++; /* since we work with k+1 everywhere */
+ tmp = (mp_limb_t*) MPFR_TMP_ALLOC(tn * BYTES_PER_MP_LIMB);
+ if (bn > k)
+ MPN_COPY (tmp, bp, bn - k);
+
+ MPFR_ASSERTD (k > 0);
+
+ /* Transform RNDD and RNDU to Zero / Away */
+ MPFR_ASSERTD((neg == 0) || (neg ==1));
+ if (MPFR_IS_RNDUTEST_OR_RNDDNOTTEST(rnd1, neg))
+ rnd1 = GMP_RNDZ;
+
+ switch (rnd1)
+ {
+ case GMP_RNDZ:
+ /* Round to Zero */
+ cc = (bp[bn - 1] >> s1) & 1;
+ cc ^= mpfr_round_raw2(bp, bn, neg, rnd2, prec);
+ /* now round b +/- 2^(MPFR_EXP(b)-err) */
+ cc2 = mpn_add_1 (tmp + bn - k, bp + bn - k, k, MPFR_LIMB_ONE << s);
+ break;
+ case GMP_RNDN:
+ /* Round to nearest */
+ /* first round b+2^(MPFR_EXP(b)-err) */
+ cc = mpn_add_1 (tmp + bn - k, bp + bn - k, k, MPFR_LIMB_ONE << s);
+ cc = (tmp[bn - 1] >> s1) & 1; /* gives 0 when cc=1 */
+ cc ^= mpfr_round_raw2 (tmp, bn, neg, rnd2, prec);
+ /* now round b-2^(MPFR_EXP(b)-err) */
+ cc2 = mpn_sub_1 (tmp + bn - k, bp + bn - k, k, MPFR_LIMB_ONE << s);
+ break;
+ default:
+ /* Round away */
+ cc = (bp[bn - 1] >> s1) & 1;
+ cc ^= mpfr_round_raw2(bp, bn, neg, rnd2, prec);
+ /* now round b +/- 2^(MPFR_EXP(b)-err) */
+ cc2 = mpn_sub_1 (tmp + bn - k, bp + bn - k, k, MPFR_LIMB_ONE << s);
+ break;
+ }
+
+ if (cc2 && cc)
+ {
+ MPFR_TMP_FREE(marker);
+ return 0;
+ }
+
+ cc2 = (tmp[bn - 1] >> s1) & 1;
+ cc2 ^= mpfr_round_raw2 (tmp, bn, neg, rnd2, prec);
+
+ MPFR_TMP_FREE(marker);
+ return cc == cc2;
+}
projects / msp430-gcc.git / blobdiff