jas_math.h
1 /*
2  * Copyright (c) 1999-2000 Image Power, Inc. and the University of
3  * British Columbia.
4  * Copyright (c) 2001-2002 Michael David Adams.
5  * All rights reserved.
6  */
7 
8 /* __START_OF_JASPER_LICENSE__
9  *
10  * JasPer License Version 2.0
11  *
12  * Copyright (c) 2001-2006 Michael David Adams
13  * Copyright (c) 1999-2000 Image Power, Inc.
14  * Copyright (c) 1999-2000 The University of British Columbia
15  *
16  * All rights reserved.
17  *
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19  * "User") obtaining a copy of this software and associated documentation
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23  * persons to whom the Software is furnished to do so, subject to the
24  * following conditions:
25  *
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27  * includes the disclaimer below) shall be included in all copies or
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58  * RISK ACTIVITIES"). THE COPYRIGHT HOLDERS SPECIFICALLY DISCLAIM ANY
59  * EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR HIGH RISK ACTIVITIES.
60  *
61  * __END_OF_JASPER_LICENSE__
62  */
63 
64 /*
65  * Math-Related Code
66  *
67  * $Id$
68  */
69 
70 #ifndef JAS_MATH_H
71 #define JAS_MATH_H
72 
73 /******************************************************************************\
74 * Includes
75 \******************************************************************************/
76 
77 /* The configuration header file should be included first. */
78 #include <jasper/jas_config.h>
79 
80 #include <jasper/jas_types.h>
81 
82 #include <assert.h>
83 #include <stdio.h>
84 #include <string.h>
85 #include <stdbool.h>
86 #include <stdint.h>
87 
88 #ifdef __cplusplus
89 extern "C" {
90 #endif
91 
92 /******************************************************************************\
93 * Macros
94 \******************************************************************************/
95 
96 #define JAS_KIBI JAS_CAST(size_t, 1024)
97 #define JAS_MEBI (JAS_KIBI * JAS_KIBI)
98 
99 /* Compute the absolute value. */
100 #define JAS_ABS(x) \
101  (((x) >= 0) ? (x) : (-(x)))
102 
103 /* Compute the minimum of two values. */
104 #define JAS_MIN(x, y) \
105  (((x) < (y)) ? (x) : (y))
106 
107 /* Compute the maximum of two values. */
108 #define JAS_MAX(x, y) \
109  (((x) > (y)) ? (x) : (y))
110 
111 /* Compute the remainder from division (where division is defined such
112  that the remainder is always nonnegative). */
113 #define JAS_MOD(x, y) \
114  (((x) < 0) ? (((-x) % (y)) ? ((y) - ((-(x)) % (y))) : (0)) : ((x) % (y)))
115 
116 /* Compute the integer with the specified number of least significant bits
117  set to one. */
118 #define JAS_ONES(n) \
119  ((1 << (n)) - 1)
120 
121 /******************************************************************************\
122 *
123 \******************************************************************************/
124 
125 JAS_ATTRIBUTE_DISABLE_USAN
126 inline static int jas_int_asr(int x, int n)
127 {
128  // Ensure that the shift of a negative value appears to behave as a
129  // signed arithmetic shift.
130  assert(((-1) >> 1) == -1);
131  assert(n >= 0);
132  // The behavior is undefined when x is negative. */
133  // We tacitly assume the behavior is equivalent to a signed
134  // arithmetic right shift.
135  return x >> n;
136 }
137 
138 JAS_ATTRIBUTE_DISABLE_USAN
139 inline static int jas_int_asl(int x, int n)
140 {
141  // Ensure that the shift of a negative value appears to behave as a
142  // signed arithmetic shift.
143  assert(((-1) << 1) == -2);
144  assert(n >= 0);
145  // The behavior is undefined when x is negative. */
146  // We tacitly assume the behavior is equivalent to a signed
147  // arithmetic left shift.
148  return x << n;
149 }
150 
151 JAS_ATTRIBUTE_DISABLE_USAN
152 inline static int jas_fast32_asr(int_fast32_t x, int n)
153 {
154  // Ensure that the shift of a negative value appears to behave as a
155  // signed arithmetic shift.
156  assert(((JAS_CAST(int_fast32_t, -1)) >> 1) == JAS_CAST(int_fast32_t, -1));
157  assert(n >= 0);
158  // The behavior is undefined when x is negative. */
159  // We tacitly assume the behavior is equivalent to a signed
160  // arithmetic right shift.
161  return x >> n;
162 }
163 
164 JAS_ATTRIBUTE_DISABLE_USAN
165 inline static int jas_fast32_asl(int_fast32_t x, int n)
166 {
167  // Ensure that the shift of a negative value appears to behave as a
168  // signed arithmetic shift.
169  assert(((JAS_CAST(int_fast32_t, -1)) << 1) == JAS_CAST(int_fast32_t, -2));
170  assert(n >= 0);
171  // The behavior is undefined when x is negative. */
172  // We tacitly assume the behavior is equivalent to a signed
173  // arithmetic left shift.
174  return x << n;
175 }
176 
177 /******************************************************************************\
178 * Safe integer arithmetic (i.e., with overflow checking).
179 \******************************************************************************/
180 
181 /* Compute the product of two size_t integers with overflow checking. */
182 inline static bool jas_safe_size_mul(size_t x, size_t y, size_t *result)
183 {
184  /* Check if overflow would occur */
185  if (x && y > SIZE_MAX / x) {
186  /* Overflow would occur. */
187  return false;
188  }
189  if (result) {
190  *result = x * y;
191  }
192  return true;
193 }
194 
195 inline static bool jas_safe_size_mul3(size_t a, size_t b, size_t c,
196  size_t *result)
197 {
198  size_t tmp;
199  if (!jas_safe_size_mul(a, b, &tmp) ||
200  !jas_safe_size_mul(tmp, c, &tmp)) {
201  return false;
202  }
203  if (result) {
204  *result = tmp;
205  }
206  return true;
207 }
208 
209 /* Compute the sum of two size_t integer with overflow checking. */
210 inline static bool jas_safe_size_add(size_t x, size_t y, size_t *result)
211 {
212  if (y > SIZE_MAX - x) {
213  return false;
214  }
215  if (result) {
216  *result = x + y;
217  }
218  return true;
219 }
220 
221 /* Compute the difference of two size_t integer with overflow checking. */
222 inline static bool jas_safe_size_sub(size_t x, size_t y, size_t *result)
223 {
224  if (y > x) {
225  return false;
226  }
227  if (result) {
228  *result = x - y;
229  }
230  return true;
231 }
232 
233 /* Compute the sum of two size_t integer with overflow checking. */
234 inline static bool jas_safe_intfast32_mul(int_fast32_t x, int_fast32_t y,
235  int_fast32_t *result)
236 {
237  if (x > 0) {
238  /* x is positive */
239  if (y > 0) {
240  /* x and y are positive */
241  if (x > INT_FAST32_MAX / y) {
242  return false;
243  }
244  } else {
245  /* x positive, y nonpositive */
246  if (y < INT_FAST32_MIN / x) {
247  return false;
248  }
249  }
250  } else {
251  /* x is nonpositive */
252  if (y > 0) {
253  /* x is nonpositive, y is positive */
254  if (x < INT_FAST32_MIN / y) {
255  return false;
256  }
257  } else { /* x and y are nonpositive */
258  if (x != 0 && y < INT_FAST32_MAX / x) {
259  return false;
260  }
261  }
262  }
263 
264  if (result) {
265  *result = x * y;
266  }
267  return true;
268 }
269 
270 inline static bool jas_safe_intfast32_mul3(int_fast32_t a, int_fast32_t b,
271  int_fast32_t c, int_fast32_t *result)
272 {
273  int_fast32_t tmp;
274  if (!jas_safe_intfast32_mul(a, b, &tmp) ||
275  !jas_safe_intfast32_mul(tmp, c, &tmp)) {
276  return false;
277  }
278  if (result) {
279  *result = tmp;
280  }
281  return true;
282 }
283 
284 /* Compute the sum of two size_t integer with overflow checking. */
285 inline static bool jas_safe_intfast32_add(int_fast32_t x, int_fast32_t y,
286  int_fast32_t *result)
287 {
288  if ((y > 0 && x > INT_FAST32_MAX - y) ||
289  (y < 0 && x < INT_FAST32_MIN - y)) {
290  return false;
291  }
292  if (result) {
293  *result = x + y;
294  }
295  return true;
296 }
297 
298 #ifdef __cplusplus
299 }
300 #endif
301 
302 #endif