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authorDuncan Wilkie <antigravityd@gmail.com>2023-11-18 06:11:09 -0600
committerDuncan Wilkie <antigravityd@gmail.com>2023-11-18 06:11:09 -0600
commit11da511c784eca003deb90c23570f0873954e0de (patch)
treee14fdd3d5d6345956d67e79ae771d0633d28362b /gmp-6.3.0/mpf/set_prc.c
Initial commit.
Diffstat (limited to 'gmp-6.3.0/mpf/set_prc.c')
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1 files changed, 68 insertions, 0 deletions
diff --git a/gmp-6.3.0/mpf/set_prc.c b/gmp-6.3.0/mpf/set_prc.c
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+/* mpf_set_prec(x) -- Change the precision of x.
+
+Copyright 1993-1995, 2000, 2001 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 either:
+
+ * 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.
+
+or
+
+ * the GNU General Public License as published by the Free Software
+ Foundation; either version 2 of the License, or (at your option) any
+ later version.
+
+or both in parallel, as here.
+
+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 General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library. If not,
+see https://www.gnu.org/licenses/. */
+
+#include "gmp-impl.h"
+
+
+/* A full new_prec+1 limbs are always retained, even though just new_prec
+ would satisfy the requested precision. If size==new_prec+1 then
+ certainly new_prec+1 should be kept since no copying is needed in that
+ case. If just new_prec was kept for size>new_prec+1 it'd be a bit
+ inconsistent. */
+
+void
+mpf_set_prec (mpf_ptr x, mp_bitcnt_t new_prec_in_bits)
+{
+ mp_size_t old_prec, new_prec, new_prec_plus1;
+ mp_size_t size, sign;
+ mp_ptr xp;
+
+ new_prec = __GMPF_BITS_TO_PREC (new_prec_in_bits);
+ old_prec = PREC(x);
+
+ /* do nothing if already the right precision */
+ if (new_prec == old_prec)
+ return;
+
+ PREC(x) = new_prec;
+ new_prec_plus1 = new_prec + 1;
+
+ /* retain most significant limbs */
+ sign = SIZ(x);
+ size = ABS (sign);
+ xp = PTR(x);
+ if (size > new_prec_plus1)
+ {
+ SIZ(x) = (sign >= 0 ? new_prec_plus1 : -new_prec_plus1);
+ MPN_COPY_INCR (xp, xp + size - new_prec_plus1, new_prec_plus1);
+ }
+
+ PTR(x) = __GMP_REALLOCATE_FUNC_LIMBS (xp, old_prec+1, new_prec_plus1);
+}