Annotation of OpenXM_contrib/gmp/mpz/setbit.c, Revision 1.1.1.3
1.1 maekawa 1: /* mpz_setbit -- set a specified bit.
2:
1.1.1.3 ! ohara 3: Copyright 1991, 1993, 1994, 1995, 1997, 1999, 2001, 2002 Free Software
! 4: Foundation, Inc.
1.1 maekawa 5:
6: This file is part of the GNU MP Library.
7:
8: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2 maekawa 9: it under the terms of the GNU Lesser General Public License as published by
10: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1 maekawa 11: option) any later version.
12:
13: The GNU MP Library is distributed in the hope that it will be useful, but
14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2 maekawa 15: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1.1 maekawa 16: License for more details.
17:
1.1.1.2 maekawa 18: You should have received a copy of the GNU Lesser General Public License
1.1 maekawa 19: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21: MA 02111-1307, USA. */
22:
23: #include "gmp.h"
24: #include "gmp-impl.h"
25:
26: void
27: mpz_setbit (mpz_ptr d, unsigned long int bit_index)
28: {
29: mp_size_t dsize = d->_mp_size;
30: mp_ptr dp = d->_mp_d;
31: mp_size_t limb_index;
32:
1.1.1.3 ! ohara 33: limb_index = bit_index / GMP_NUMB_BITS;
1.1 maekawa 34: if (dsize >= 0)
35: {
36: if (limb_index < dsize)
37: {
1.1.1.3 ! ohara 38: dp[limb_index] |= (mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS);
1.1 maekawa 39: d->_mp_size = dsize;
40: }
41: else
42: {
43: /* Ugh. The bit should be set outside of the end of the
44: number. We have to increase the size of the number. */
45: if (d->_mp_alloc < limb_index + 1)
46: {
47: _mpz_realloc (d, limb_index + 1);
48: dp = d->_mp_d;
49: }
50: MPN_ZERO (dp + dsize, limb_index - dsize);
1.1.1.3 ! ohara 51: dp[limb_index] = (mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS);
1.1 maekawa 52: d->_mp_size = limb_index + 1;
53: }
54: }
55: else
56: {
57: mp_size_t zero_bound;
58:
59: /* Simulate two's complement arithmetic, i.e. simulate
60: 1. Set OP = ~(OP - 1) [with infinitely many leading ones].
1.1.1.2 maekawa 61: 2. Set the bit.
1.1 maekawa 62: 3. Set OP = ~OP + 1. */
63:
64: dsize = -dsize;
65:
66: /* No upper bound on this loop, we're sure there's a non-zero limb
67: sooner ot later. */
68: for (zero_bound = 0; ; zero_bound++)
69: if (dp[zero_bound] != 0)
70: break;
71:
72: if (limb_index > zero_bound)
73: {
74: if (limb_index < dsize)
1.1.1.3 ! ohara 75: {
! 76: dp[limb_index] &= ~((mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS));
! 77: MPN_NORMALIZE (dp, dsize);
! 78: d->_mp_size = -dsize;
! 79: }
1.1 maekawa 80: }
81: else if (limb_index == zero_bound)
82: {
83: dp[limb_index] = ((dp[limb_index] - 1)
1.1.1.3 ! ohara 84: & ~((mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS))) + 1;
1.1 maekawa 85: if (dp[limb_index] == 0)
86: {
87: mp_size_t i;
88: for (i = limb_index + 1; i < dsize; i++)
89: {
90: dp[i] += 1;
91: if (dp[i] != 0)
92: goto fin;
93: }
94: /* We got carry all way out beyond the end of D. Increase
95: its size (and allocation if necessary). */
96: dsize++;
97: if (d->_mp_alloc < dsize)
98: {
99: _mpz_realloc (d, dsize);
100: dp = d->_mp_d;
101: }
102: dp[i] = 1;
103: d->_mp_size = -dsize;
104: fin:;
105: }
106: }
107: else
1.1.1.2 maekawa 108: {
109: mpn_decr_u (dp + limb_index,
1.1.1.3 ! ohara 110: (mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS));
1.1.1.2 maekawa 111: dsize -= dp[dsize - 1] == 0;
112: d->_mp_size = -dsize;
113: }
1.1 maekawa 114: }
115: }
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