From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001
From: Duncan Wilkie <antigravityd@gmail.com>
Date: Sat, 18 Nov 2023 06:11:09 -0600
Subject: Initial commit.

---
 gmp-6.3.0/mpz/setbit.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 gmp-6.3.0/mpz/setbit.c

(limited to 'gmp-6.3.0/mpz/setbit.c')

diff --git a/gmp-6.3.0/mpz/setbit.c b/gmp-6.3.0/mpz/setbit.c
new file mode 100644
index 0000000..228a564
--- /dev/null
+++ b/gmp-6.3.0/mpz/setbit.c
@@ -0,0 +1,104 @@
+/* mpz_setbit -- set a specified bit.
+
+Copyright 1991, 1993-1995, 1997, 1999, 2001, 2002, 2012 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"
+
+void
+mpz_setbit (mpz_ptr d, mp_bitcnt_t bit_idx)
+{
+  mp_size_t dsize = SIZ (d);
+  mp_ptr dp = PTR (d);
+  mp_size_t limb_idx;
+  mp_limb_t mask;
+
+  limb_idx = bit_idx / GMP_NUMB_BITS;
+  mask = CNST_LIMB(1) << (bit_idx % GMP_NUMB_BITS);
+  if (dsize >= 0)
+    {
+      if (limb_idx < dsize)
+	{
+	  dp[limb_idx] |= mask;
+	}
+      else
+	{
+	  /* Ugh.  The bit should be set outside of the end of the
+	     number.  We have to increase the size of the number.  */
+	  dp = MPZ_REALLOC (d, limb_idx + 1);
+	  SIZ (d) = limb_idx + 1;
+	  MPN_ZERO (dp + dsize, limb_idx - dsize);
+	  dp[limb_idx] = mask;
+	}
+    }
+  else
+    {
+      /* Simulate two's complement arithmetic, i.e. simulate
+	 1. Set OP = ~(OP - 1) [with infinitely many leading ones].
+	 2. Set the bit.
+	 3. Set OP = ~OP + 1.  */
+
+      dsize = -dsize;
+
+      if (limb_idx < dsize)
+	{
+	  mp_size_t zero_bound;
+	  /* No index upper bound on this loop, we're sure there's a non-zero limb
+	     sooner or later.  */
+	  zero_bound = 0;
+	  while (dp[zero_bound] == 0)
+	    zero_bound++;
+
+	  if (limb_idx > zero_bound)
+	    {
+	      mp_limb_t	 dlimb;
+	      dlimb = dp[limb_idx] & ~mask;
+	      dp[limb_idx] = dlimb;
+
+	      if (UNLIKELY ((dlimb == 0) + limb_idx == dsize)) /* dsize == limb_idx + 1 */
+		{
+		  /* high limb became zero, must normalize */
+		  MPN_NORMALIZE (dp, limb_idx);
+		  SIZ (d) = -limb_idx;
+		}
+	    }
+	  else if (limb_idx == zero_bound)
+	    {
+	      dp[limb_idx] = ((dp[limb_idx] - 1) & ~mask) + 1;
+	      ASSERT (dp[limb_idx] != 0);
+	    }
+	  else
+	    {
+	      MPN_DECR_U (dp + limb_idx, dsize - limb_idx, mask);
+	      dsize -= dp[dsize - 1] == 0;
+	      SIZ (d) = -dsize;
+	    }
+	}
+    }
+}
-- 
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