aboutsummaryrefslogtreecommitdiff
path: root/vendor/gmp-6.3.0/mpq/md_2exp.c
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/gmp-6.3.0/mpq/md_2exp.c')
-rw-r--r--vendor/gmp-6.3.0/mpq/md_2exp.c110
1 files changed, 110 insertions, 0 deletions
diff --git a/vendor/gmp-6.3.0/mpq/md_2exp.c b/vendor/gmp-6.3.0/mpq/md_2exp.c
new file mode 100644
index 0000000..b3378b3
--- /dev/null
+++ b/vendor/gmp-6.3.0/mpq/md_2exp.c
@@ -0,0 +1,110 @@
+/* mpq_mul_2exp, mpq_div_2exp - multiply or divide by 2^N */
+
+/*
+Copyright 2000, 2002, 2012, 2018 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"
+#include "longlong.h"
+
+
+/* The multiplier/divisor "n", representing 2^n, is applied by right shifting
+ "r" until it's odd (if it isn't already), and left shifting "l" for the
+ rest. */
+
+static void
+mord_2exp (mpz_ptr ldst, mpz_ptr rdst, mpz_srcptr lsrc, mpz_srcptr rsrc,
+ mp_bitcnt_t n)
+{
+ mp_size_t rsrc_size = SIZ(rsrc);
+ mp_size_t len = ABS (rsrc_size);
+ mp_ptr rsrc_ptr = PTR(rsrc);
+ mp_ptr p, rdst_ptr;
+ mp_limb_t plow;
+
+ p = rsrc_ptr;
+ plow = *p;
+ while (n >= GMP_NUMB_BITS && plow == 0)
+ {
+ n -= GMP_NUMB_BITS;
+ p++;
+ plow = *p;
+ }
+
+ /* no realloc here if rsrc==rdst, so p and rsrc_ptr remain valid */
+ len -= (p - rsrc_ptr);
+ rdst_ptr = MPZ_REALLOC (rdst, len);
+
+ if ((plow & 1) || n == 0)
+ {
+ /* need INCR when src==dst */
+ if (p != rdst_ptr)
+ MPN_COPY_INCR (rdst_ptr, p, len);
+ }
+ else
+ {
+ unsigned long shift;
+ if (plow == 0)
+ shift = n;
+ else
+ {
+ count_trailing_zeros (shift, plow);
+ shift = MIN (shift, n);
+ }
+ mpn_rshift (rdst_ptr, p, len, shift);
+ len -= (rdst_ptr[len-1] == 0);
+ n -= shift;
+ }
+ SIZ(rdst) = (rsrc_size >= 0) ? len : -len;
+
+ if (n)
+ mpz_mul_2exp (ldst, lsrc, n);
+ else if (ldst != lsrc)
+ mpz_set (ldst, lsrc);
+}
+
+
+void
+mpq_mul_2exp (mpq_ptr dst, mpq_srcptr src, mp_bitcnt_t n)
+{
+ mord_2exp (NUM(dst), DEN(dst), NUM(src), DEN(src), n);
+}
+
+void
+mpq_div_2exp (mpq_ptr dst, mpq_srcptr src, mp_bitcnt_t n)
+{
+ if (SIZ(NUM(src)) == 0)
+ {
+ SIZ(NUM(dst)) = 0;
+ SIZ(DEN(dst)) = 1;
+ MPZ_NEWALLOC (DEN(dst), 1)[0] = 1;
+ return;
+ }
+
+ mord_2exp (DEN(dst), NUM(dst), DEN(src), NUM(src), n);
+}