1 /* mpf_ui_div -- Divide an unsigned integer with a float.
2
3 Copyright 1993-1996, 2000-2002, 2004, 2005, 2012 Free Software Foundation, Inc.
4
5 This file is part of the GNU MP Library.
6
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of either:
9
10 * the GNU Lesser General Public License as published by the Free
11 Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
13
14 or
15
16 * the GNU General Public License as published by the Free Software
17 Foundation; either version 2 of the License, or (at your option) any
18 later version.
19
20 or both in parallel, as here.
21
22 The GNU MP Library is distributed in the hope that it will be useful, but
23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
25 for more details.
26
27 You should have received copies of the GNU General Public License and the
28 GNU Lesser General Public License along with the GNU MP Library. If not,
29 see https://www.gnu.org/licenses/. */
30
31 #include <stdio.h> /* for NULL */
32 #include "gmp-impl.h"
33 #include "longlong.h"
34
35
36 void
mpf_ui_div(mpf_ptr r,unsigned long int u,mpf_srcptr v)37 mpf_ui_div (mpf_ptr r, unsigned long int u, mpf_srcptr v)
38 {
39 mp_srcptr vp;
40 mp_ptr rp, tp, remp, new_vp;
41 mp_size_t vsize;
42 mp_size_t rsize, prospective_rsize, zeros, tsize, high_zero;
43 mp_size_t sign_quotient;
44 mp_size_t prec;
45 mp_exp_t rexp;
46 TMP_DECL;
47
48 vsize = v->_mp_size;
49 sign_quotient = vsize;
50
51 if (UNLIKELY (vsize == 0))
52 DIVIDE_BY_ZERO;
53
54 if (UNLIKELY (u == 0))
55 {
56 r->_mp_size = 0;
57 r->_mp_exp = 0;
58 return;
59 }
60
61 vsize = ABS (vsize);
62 prec = r->_mp_prec;
63
64 TMP_MARK;
65 rexp = 1 - v->_mp_exp + 1;
66
67 rp = r->_mp_d;
68 vp = v->_mp_d;
69
70 prospective_rsize = 1 - vsize + 1; /* quot from using given u,v sizes */
71 rsize = prec + 1; /* desired quot size */
72
73 zeros = rsize - prospective_rsize; /* padding u to give rsize */
74 tsize = 1 + zeros; /* u with zeros */
75
76 if (WANT_TMP_DEBUG)
77 {
78 /* separate alloc blocks, for malloc debugging */
79 remp = TMP_ALLOC_LIMBS (vsize);
80 tp = TMP_ALLOC_LIMBS (tsize);
81 new_vp = NULL;
82 if (rp == vp)
83 new_vp = TMP_ALLOC_LIMBS (vsize);
84 }
85 else
86 {
87 /* one alloc with calculated size, for efficiency */
88 mp_size_t size = vsize + tsize + (rp == vp ? vsize : 0);
89 remp = TMP_ALLOC_LIMBS (size);
90 tp = remp + vsize;
91 new_vp = tp + tsize;
92 }
93
94 /* ensure divisor doesn't overlap quotient */
95 if (rp == vp)
96 {
97 MPN_COPY (new_vp, vp, vsize);
98 vp = new_vp;
99 }
100
101 MPN_ZERO (tp, tsize-1);
102
103 tp[tsize - 1] = u & GMP_NUMB_MASK;
104 #if BITS_PER_ULONG > GMP_NUMB_BITS
105 if (u > GMP_NUMB_MAX)
106 {
107 /* tsize-vsize+1 == rsize, so tsize >= rsize. rsize == prec+1 >= 2,
108 so tsize >= 2, hence there's room for 2-limb u with nails */
109 ASSERT (tsize >= 2);
110 tp[tsize - 1] = u >> GMP_NUMB_BITS;
111 tp[tsize - 2] = u & GMP_NUMB_MASK;
112 rexp++;
113 }
114 #endif
115
116 ASSERT (tsize-vsize+1 == rsize);
117 mpn_tdiv_qr (rp, remp, (mp_size_t) 0, tp, tsize, vp, vsize);
118
119 /* strip possible zero high limb */
120 high_zero = (rp[rsize-1] == 0);
121 rsize -= high_zero;
122 rexp -= high_zero;
123
124 r->_mp_size = sign_quotient >= 0 ? rsize : -rsize;
125 r->_mp_exp = rexp;
126 TMP_FREE;
127 }
128