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2 //
3 // Copyright (c) 2002-2012, Industrial Light & Magic, a division of Lucas
4 // Digital Ltd. LLC
5 //
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32 //
33 ///////////////////////////////////////////////////////////////////////////
34
35
36 #include "ImathFun.h"
37
38 IMATH_INTERNAL_NAMESPACE_SOURCE_ENTER
39
40
41 float
succf(float f)42 succf (float f)
43 {
44 union {float f; int i;} u;
45 u.f = f;
46
47 if ((u.i & 0x7f800000) == 0x7f800000)
48 {
49 // Nan or infinity; don't change value.
50 }
51 else if (u.i == 0x00000000 || u.i == 0x80000000)
52 {
53 // Plus or minus zero.
54
55 u.i = 0x00000001;
56 }
57 else if (u.i > 0)
58 {
59 // Positive float, normalized or denormalized.
60 // Incrementing the largest positive float
61 // produces +infinity.
62
63 ++u.i;
64 }
65 else
66 {
67 // Negative normalized or denormalized float.
68
69 --u.i;
70 }
71
72 return u.f;
73 }
74
75
76 float
predf(float f)77 predf (float f)
78 {
79 union {float f; int i;} u;
80 u.f = f;
81
82 if ((u.i & 0x7f800000) == 0x7f800000)
83 {
84 // Nan or infinity; don't change value.
85 }
86 else if (u.i == 0x00000000 || u.i == 0x80000000)
87 {
88 // Plus or minus zero.
89
90 u.i = 0x80000001;
91 }
92 else if (u.i > 0)
93 {
94 // Positive float, normalized or denormalized.
95
96 --u.i;
97 }
98 else
99 {
100 // Negative normalized or denormalized float.
101 // Decrementing the largest negative float
102 // produces -infinity.
103
104 ++u.i;
105 }
106
107 return u.f;
108 }
109
110
111 double
succd(double d)112 succd (double d)
113 {
114 union {double d; Int64 i;} u;
115 u.d = d;
116
117 if ((u.i & 0x7ff0000000000000LL) == 0x7ff0000000000000LL)
118 {
119 // Nan or infinity; don't change value.
120 }
121 else if (u.i == 0x0000000000000000LL || u.i == 0x8000000000000000LL)
122 {
123 // Plus or minus zero.
124
125 u.i = 0x0000000000000001LL;
126 }
127 else if (u.d > 0)
128 {
129 // Positive double, normalized or denormalized.
130 // Incrementing the largest positive double
131 // produces +infinity.
132
133 ++u.i;
134 }
135 else
136 {
137 // Negative normalized or denormalized double.
138
139 --u.i;
140 }
141
142 return u.d;
143 }
144
145
146 double
predd(double d)147 predd (double d)
148 {
149 union {double d; Int64 i;} u;
150 u.d = d;
151
152 if ((u.i & 0x7ff0000000000000LL) == 0x7ff0000000000000LL)
153 {
154 // Nan or infinity; don't change value.
155 }
156 else if (u.i == 0x0000000000000000LL || u.i == 0x8000000000000000LL)
157 {
158 // Plus or minus zero.
159
160 u.i = 0x8000000000000001LL;
161 }
162 else if (u.d > 0)
163 {
164 // Positive double, normalized or denormalized.
165
166 --u.i;
167 }
168 else
169 {
170 // Negative normalized or denormalized double.
171 // Decrementing the largest negative double
172 // produces -infinity.
173
174 ++u.i;
175 }
176
177 return u.d;
178 }
179
180
181 IMATH_INTERNAL_NAMESPACE_SOURCE_EXIT
182