--- /dev/null
+/* mpf_ui_sub -- Subtract a float from an unsigned long int.
+
+Copyright 1993, 1994, 1995, 1996, 2001, 2002, 2005 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"
+
+void
+mpf_ui_sub (mpf_ptr r, unsigned long int u, mpf_srcptr v)
+{
+ mp_srcptr up, vp;
+ mp_ptr rp, tp;
+ mp_size_t usize, vsize, rsize;
+ mp_size_t prec;
+ mp_exp_t uexp;
+ mp_size_t ediff;
+ int negate;
+ mp_limb_t ulimb;
+ TMP_DECL;
+
+ vsize = v->_mp_size;
+
+ /* Handle special cases that don't work in generic code below. */
+ if (u == 0)
+ {
+ mpf_neg (r, v);
+ return;
+ }
+ if (vsize == 0)
+ {
+ mpf_set_ui (r, u);
+ return;
+ }
+
+ /* If signs of U and V are different, perform addition. */
+ if (vsize < 0)
+ {
+ __mpf_struct v_negated;
+ v_negated._mp_size = -vsize;
+ v_negated._mp_exp = v->_mp_exp;
+ v_negated._mp_d = v->_mp_d;
+ mpf_add_ui (r, &v_negated, u);
+ return;
+ }
+
+ TMP_MARK;
+
+ /* Signs are now known to be the same. */
+
+ ulimb = u;
+ /* Make U be the operand with the largest exponent. */
+ if (1 < v->_mp_exp)
+ {
+ negate = 1;
+ usize = ABS (vsize);
+ vsize = 1;
+ up = v->_mp_d;
+ vp = &ulimb;
+ rp = r->_mp_d;
+ prec = r->_mp_prec + 1;
+ uexp = v->_mp_exp;
+ ediff = uexp - 1;
+ }
+ else
+ {
+ negate = 0;
+ usize = 1;
+ vsize = ABS (vsize);
+ up = &ulimb;
+ vp = v->_mp_d;
+ rp = r->_mp_d;
+ prec = r->_mp_prec;
+ uexp = 1;
+ ediff = 1 - v->_mp_exp;
+ }
+
+ /* Ignore leading limbs in U and V that are equal. Doing
+ this helps increase the precision of the result. */
+ if (ediff == 0)
+ {
+ /* This loop normally exits immediately. Optimize for that. */
+ for (;;)
+ {
+ usize--;
+ vsize--;
+ if (up[usize] != vp[vsize])
+ break;
+ uexp--;
+ if (usize == 0)
+ goto Lu0;
+ if (vsize == 0)
+ goto Lv0;
+ }
+ usize++;
+ vsize++;
+ /* Note that either operand (but not both operands) might now have
+ leading zero limbs. It matters only that U is unnormalized if
+ vsize is now zero, and vice versa. And it is only in that case
+ that we have to adjust uexp. */
+ if (vsize == 0)
+ Lv0:
+ while (usize != 0 && up[usize - 1] == 0)
+ usize--, uexp--;
+ if (usize == 0)
+ Lu0:
+ while (vsize != 0 && vp[vsize - 1] == 0)
+ vsize--, uexp--;
+ }
+
+ /* If U extends beyond PREC, ignore the part that does. */
+ if (usize > prec)
+ {
+ up += usize - prec;
+ usize = prec;
+ }
+
+ /* If V extends beyond PREC, ignore the part that does.
+ Note that this may make vsize negative. */
+ if (vsize + ediff > prec)
+ {
+ vp += vsize + ediff - prec;
+ vsize = prec - ediff;
+ }
+
+ /* Allocate temp space for the result. Allocate
+ just vsize + ediff later??? */
+ tp = (mp_ptr) TMP_ALLOC (prec * BYTES_PER_MP_LIMB);
+
+ if (ediff >= prec)
+ {
+ /* V completely cancelled. */
+ if (tp != up)
+ MPN_COPY (rp, up, usize);
+ rsize = usize;
+ }
+ else
+ {
+ /* Locate the least significant non-zero limb in (the needed
+ parts of) U and V, to simplify the code below. */
+ for (;;)
+ {
+ if (vsize == 0)
+ {
+ MPN_COPY (rp, up, usize);
+ rsize = usize;
+ goto done;
+ }
+ if (vp[0] != 0)
+ break;
+ vp++, vsize--;
+ }
+ for (;;)
+ {
+ if (usize == 0)
+ {
+ MPN_COPY (rp, vp, vsize);
+ rsize = vsize;
+ negate ^= 1;
+ goto done;
+ }
+ if (up[0] != 0)
+ break;
+ up++, usize--;
+ }
+
+ /* uuuu | uuuu | uuuu | uuuu | uuuu */
+ /* vvvvvvv | vv | vvvvv | v | vv */
+
+ if (usize > ediff)
+ {
+ /* U and V partially overlaps. */
+ if (ediff == 0)
+ {
+ /* Have to compare the leading limbs of u and v
+ to determine whether to compute u - v or v - u. */
+ if (usize > vsize)
+ {
+ /* uuuu */
+ /* vv */
+ int cmp;
+ cmp = mpn_cmp (up + usize - vsize, vp, vsize);
+ if (cmp >= 0)
+ {
+ mp_size_t size;
+ size = usize - vsize;
+ MPN_COPY (tp, up, size);
+ mpn_sub_n (tp + size, up + size, vp, vsize);
+ rsize = usize;
+ }
+ else
+ {
+ /* vv */ /* Swap U and V. */
+ /* uuuu */
+ mp_size_t size, i;
+ size = usize - vsize;
+ tp[0] = -up[0] & GMP_NUMB_MASK;
+ for (i = 1; i < size; i++)
+ tp[i] = ~up[i] & GMP_NUMB_MASK;
+ mpn_sub_n (tp + size, vp, up + size, vsize);
+ mpn_sub_1 (tp + size, tp + size, vsize, (mp_limb_t) 1);
+ negate ^= 1;
+ rsize = usize;
+ }
+ }
+ else if (usize < vsize)
+ {
+ /* uuuu */
+ /* vvvvvvv */
+ int cmp;
+ cmp = mpn_cmp (up, vp + vsize - usize, usize);
+ if (cmp > 0)
+ {
+ mp_size_t size, i;
+ size = vsize - usize;
+ tp[0] = -vp[0] & GMP_NUMB_MASK;
+ for (i = 1; i < size; i++)
+ tp[i] = ~vp[i] & GMP_NUMB_MASK;
+ mpn_sub_n (tp + size, up, vp + size, usize);
+ mpn_sub_1 (tp + size, tp + size, usize, (mp_limb_t) 1);
+ rsize = vsize;
+ }
+ else
+ {
+ /* vvvvvvv */ /* Swap U and V. */
+ /* uuuu */
+ /* This is the only place we can get 0.0. */
+ mp_size_t size;
+ size = vsize - usize;
+ MPN_COPY (tp, vp, size);
+ mpn_sub_n (tp + size, vp + size, up, usize);
+ negate ^= 1;
+ rsize = vsize;
+ }
+ }
+ else
+ {
+ /* uuuu */
+ /* vvvv */
+ int cmp;
+ cmp = mpn_cmp (up, vp + vsize - usize, usize);
+ if (cmp > 0)
+ {
+ mpn_sub_n (tp, up, vp, usize);
+ rsize = usize;
+ }
+ else
+ {
+ mpn_sub_n (tp, vp, up, usize);
+ negate ^= 1;
+ rsize = usize;
+ /* can give zero */
+ }
+ }
+ }
+ else
+ {
+ if (vsize + ediff <= usize)
+ {
+ /* uuuu */
+ /* v */
+ mp_size_t size;
+ size = usize - ediff - vsize;
+ MPN_COPY (tp, up, size);
+ mpn_sub (tp + size, up + size, usize - size, vp, vsize);
+ rsize = usize;
+ }
+ else
+ {
+ /* uuuu */
+ /* vvvvv */
+ mp_size_t size, i;
+ size = vsize + ediff - usize;
+ tp[0] = -vp[0] & GMP_NUMB_MASK;
+ for (i = 1; i < size; i++)
+ tp[i] = ~vp[i] & GMP_NUMB_MASK;
+ mpn_sub (tp + size, up, usize, vp + size, usize - ediff);
+ mpn_sub_1 (tp + size, tp + size, usize, (mp_limb_t) 1);
+ rsize = vsize + ediff;
+ }
+ }
+ }
+ else
+ {
+ /* uuuu */
+ /* vv */
+ mp_size_t size, i;
+ size = vsize + ediff - usize;
+ tp[0] = -vp[0] & GMP_NUMB_MASK;
+ for (i = 1; i < vsize; i++)
+ tp[i] = ~vp[i] & GMP_NUMB_MASK;
+ for (i = vsize; i < size; i++)
+ tp[i] = GMP_NUMB_MAX;
+ mpn_sub_1 (tp + size, up, usize, (mp_limb_t) 1);
+ rsize = size + usize;
+ }
+
+ /* Full normalize. Optimize later. */
+ while (rsize != 0 && tp[rsize - 1] == 0)
+ {
+ rsize--;
+ uexp--;
+ }
+ MPN_COPY (rp, tp, rsize);
+ }
+
+ done:
+ r->_mp_size = negate ? -rsize : rsize;
+ r->_mp_exp = uexp;
+ TMP_FREE;
+}
projects / msp430-gcc.git / blobdiff