1 /* mpz_cmp_d -- compare absolute values of mpz and double.
2
3 Copyright 2001, 2002, 2003 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 the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
11
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
16
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
19
20 #include "config.h"
21
22 #if HAVE_FLOAT_H
23 #include <float.h> /* for DBL_MAX */
24 #endif
25
26 #include "gmp.h"
27 #include "gmp-impl.h"
28
29
30 #define RETURN_CMP(zl, dl) \
31 do { \
32 zlimb = (zl); \
33 dlimb = (dl); \
34 if (zlimb != dlimb) \
35 return (zlimb >= dlimb ? ret : -ret); \
36 } while (0)
37
38 #define RETURN_NONZERO(ptr, size, val) \
39 do { \
40 mp_size_t __i; \
41 for (__i = (size)-1; __i >= 0; __i--) \
42 if ((ptr)[__i] != 0) \
43 return val; \
44 return 0; \
45 } while (0)
46
47
48 int
mpz_cmp_d(mpz_srcptr z,double d)49 mpz_cmp_d (mpz_srcptr z, double d)
50 {
51 mp_limb_t darray[LIMBS_PER_DOUBLE], zlimb, dlimb;
52 mp_srcptr zp;
53 mp_size_t zsize;
54 int dexp, ret;
55
56 /* d=NaN is an invalid operation, there's no sensible return value.
57 d=Inf or -Inf is always bigger than z. */
58 DOUBLE_NAN_INF_ACTION (d, __gmp_invalid_operation (), goto z_zero);
59
60 /* 1. Either operand zero. */
61 zsize = SIZ(z);
62 if (d == 0.0)
63 return zsize;
64 if (zsize == 0)
65 {
66 z_zero:
67 return (d < 0.0 ? 1 : -1);
68 }
69
70 /* 2. Opposite signs. */
71 if (zsize >= 0)
72 {
73 if (d < 0.0)
74 return 1; /* >=0 cmp <0 */
75 ret = 1;
76 }
77 else
78 {
79 if (d >= 0.0)
80 return -1; /* <0 cmp >=0 */
81 ret = -1;
82 d = -d;
83 zsize = -zsize;
84 }
85
86 /* 3. Small d, knowing abs(z) >= 1. */
87 if (d < 1.0)
88 return ret;
89
90 dexp = __gmp_extract_double (darray, d);
91 ASSERT (dexp >= 1);
92
93 /* 4. Check for different high limb positions. */
94 if (zsize != dexp)
95 return (zsize >= dexp ? ret : -ret);
96
97 /* 5. Limb data. */
98 zp = PTR(z);
99
100 #if LIMBS_PER_DOUBLE == 2
101 RETURN_CMP (zp[zsize-1], darray[1]);
102 if (zsize == 1)
103 return (darray[0] != 0 ? -ret : 0);
104
105 RETURN_CMP (zp[zsize-2], darray[0]);
106 RETURN_NONZERO (zp, zsize-2, ret);
107 #endif
108
109 #if LIMBS_PER_DOUBLE == 3
110 RETURN_CMP (zp[zsize-1], darray[2]);
111 if (zsize == 1)
112 return ((darray[0] | darray[1]) != 0 ? -ret : 0);
113
114 RETURN_CMP (zp[zsize-2], darray[1]);
115 if (zsize == 2)
116 return (darray[0] != 0 ? -ret : 0);
117
118 RETURN_CMP (zp[zsize-3], darray[0]);
119 RETURN_NONZERO (zp, zsize-3, ret);
120 #endif
121
122 #if LIMBS_PER_DOUBLE >= 4
123 {
124 int i;
125 for (i = 1; i <= LIMBS_PER_DOUBLE; i++)
126 {
127 RETURN_CMP (zp[zsize-i], darray[LIMBS_PER_DOUBLE-i]);
128 if (i >= zsize)
129 RETURN_NONZERO (darray, LIMBS_PER_DOUBLE-i, -ret);
130 }
131 RETURN_NONZERO (zp, zsize-LIMBS_PER_DOUBLE, ret);
132 }
133 #endif
134 }
135