JasPer  2.0.23
jas_math.h
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4  * Copyright (c) 2001-2002 Michael David Adams.
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63 
69 #ifndef JAS_MATH_H
70 #define JAS_MATH_H
71 
72 /******************************************************************************\
73 * Includes
74 \******************************************************************************/
75 
76 /* The configuration header file should be included first. */
77 #include <jasper/jas_config.h>
78 
79 #include <jasper/jas_types.h>
80 
81 #include <assert.h>
82 #include <string.h>
83 #include <stdint.h>
84 #include <limits.h>
85 
86 #ifdef __cplusplus
87 extern "C" {
88 #endif
89 
90 /******************************************************************************\
91 * Macros
92 \******************************************************************************/
93 
94 #define JAS_KIBI JAS_CAST(size_t, 1024)
95 #define JAS_MEBI (JAS_KIBI * JAS_KIBI)
96 
97 /* Compute the absolute value. */
98 #define JAS_ABS(x) \
99  (((x) >= 0) ? (x) : (-(x)))
100 
101 /* Compute the minimum of two values. */
102 #define JAS_MIN(x, y) \
103  (((x) < (y)) ? (x) : (y))
104 
105 /* Compute the maximum of two values. */
106 #define JAS_MAX(x, y) \
107  (((x) > (y)) ? (x) : (y))
108 
109 /* Compute the remainder from division (where division is defined such
110  that the remainder is always nonnegative). */
111 #define JAS_MOD(x, y) \
112  (((x) < 0) ? (((-x) % (y)) ? ((y) - ((-(x)) % (y))) : (0)) : ((x) % (y)))
113 
114 /* Compute the integer with the specified number of least significant bits
115  set to one. */
116 #define JAS_ONES(n) \
117  ((1 << (n)) - 1)
118 
119 /******************************************************************************\
120 *
121 \******************************************************************************/
122 
123 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 6)
124 /* suppress clang warning "shifting a negative signed value is
125  undefined" in the assertions below */
126 #pragma GCC diagnostic push
127 #pragma GCC diagnostic ignored "-Wshift-negative-value"
128 #endif
129 
130 JAS_ATTRIBUTE_CONST
131 JAS_ATTRIBUTE_DISABLE_USAN
132 inline static int jas_int_asr(int x, unsigned n)
133 {
134  // Ensure that the shift of a negative value appears to behave as a
135  // signed arithmetic shift.
136  assert(((-1) >> 1) == -1);
137  // The behavior is undefined when x is negative. */
138  // We tacitly assume the behavior is equivalent to a signed
139  // arithmetic right shift.
140  return x >> n;
141 }
142 
143 JAS_ATTRIBUTE_CONST
144 JAS_ATTRIBUTE_DISABLE_USAN
145 inline static int jas_int_asl(int x, unsigned n)
146 {
147  // Ensure that the shift of a negative value appears to behave as a
148  // signed arithmetic shift.
149  assert(((-1) << 1) == -2);
150  // The behavior is undefined when x is negative. */
151  // We tacitly assume the behavior is equivalent to a signed
152  // arithmetic left shift.
153  return x << n;
154 }
155 
156 JAS_ATTRIBUTE_CONST
157 JAS_ATTRIBUTE_DISABLE_USAN
158 inline static int_least32_t jas_least32_asr(int_least32_t x, unsigned n)
159 {
160  // Ensure that the shift of a negative value appears to behave as a
161  // signed arithmetic shift.
162  assert(((JAS_CAST(int_least32_t, -1)) >> 1) == JAS_CAST(int_least32_t, -1));
163  // The behavior is undefined when x is negative. */
164  // We tacitly assume the behavior is equivalent to a signed
165  // arithmetic right shift.
166  return x >> n;
167 }
168 
169 JAS_ATTRIBUTE_CONST
170 JAS_ATTRIBUTE_DISABLE_USAN
171 inline static int_least32_t jas_least32_asl(int_least32_t x, unsigned n)
172 {
173  // Ensure that the shift of a negative value appears to behave as a
174  // signed arithmetic shift.
175  assert(((JAS_CAST(int_least32_t, -1)) << 1) == JAS_CAST(int_least32_t, -2));
176  // The behavior is undefined when x is negative. */
177  // We tacitly assume the behavior is equivalent to a signed
178  // arithmetic left shift.
179  return x << n;
180 }
181 
182 JAS_ATTRIBUTE_CONST
183 JAS_ATTRIBUTE_DISABLE_USAN
184 inline static int_fast32_t jas_fast32_asr(int_fast32_t x, unsigned n)
185 {
186  // Ensure that the shift of a negative value appears to behave as a
187  // signed arithmetic shift.
188  assert(((JAS_CAST(int_fast32_t, -1)) >> 1) == JAS_CAST(int_fast32_t, -1));
189  // The behavior is undefined when x is negative. */
190  // We tacitly assume the behavior is equivalent to a signed
191  // arithmetic right shift.
192  return x >> n;
193 }
194 
195 JAS_ATTRIBUTE_CONST
196 JAS_ATTRIBUTE_DISABLE_USAN
197 inline static int_fast32_t jas_fast32_asl(int_fast32_t x, unsigned n)
198 {
199  // Ensure that the shift of a negative value appears to behave as a
200  // signed arithmetic shift.
201  assert(((JAS_CAST(int_fast32_t, -1)) << 1) == JAS_CAST(int_fast32_t, -2));
202  // The behavior is undefined when x is negative. */
203  // We tacitly assume the behavior is equivalent to a signed
204  // arithmetic left shift.
205  return x << n;
206 }
207 
208 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 6)
209 #pragma GCC diagnostic pop
210 #endif
211 
212 /******************************************************************************\
213 * Safe integer arithmetic (i.e., with overflow checking).
214 \******************************************************************************/
215 
216 /* Compute the product of two size_t integers with overflow checking. */
217 inline static bool jas_safe_size_mul(size_t x, size_t y, size_t *result)
218 {
219 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 5)
220  size_t result_buffer;
221  if (!result)
222  result = &result_buffer;
223  return !__builtin_mul_overflow(x, y, result);
224 #else
225  /* Check if overflow would occur */
226  if (x && y > SIZE_MAX / x) {
227  /* Overflow would occur. */
228  return false;
229  }
230  if (result) {
231  *result = x * y;
232  }
233  return true;
234 #endif
235 }
236 
237 /* Compute the product of three size_t integers with overflow checking. */
238 inline static bool jas_safe_size_mul3(size_t a, size_t b, size_t c,
239  size_t *result)
240 {
241  size_t tmp;
242  if (!jas_safe_size_mul(a, b, &tmp) ||
243  !jas_safe_size_mul(tmp, c, &tmp)) {
244  return false;
245  }
246  if (result) {
247  *result = tmp;
248  }
249  return true;
250 }
251 
252 /* Compute the sum of two size_t integers with overflow checking. */
253 inline static bool jas_safe_size_add(size_t x, size_t y, size_t *result)
254 {
255 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 5)
256  size_t result_buffer;
257  if (!result)
258  result = &result_buffer;
259  return !__builtin_add_overflow(x, y, result);
260 #else
261  if (y > SIZE_MAX - x) {
262  return false;
263  }
264  if (result) {
265  *result = x + y;
266  }
267  return true;
268 #endif
269 }
270 
271 /* Compute the difference of two size_t integers with overflow checking. */
272 inline static bool jas_safe_size_sub(size_t x, size_t y, size_t *result)
273 {
274 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 5)
275  size_t result_buffer;
276  if (!result)
277  result = &result_buffer;
278  return !__builtin_sub_overflow(x, y, result);
279 #else
280  if (y > x) {
281  return false;
282  }
283  if (result) {
284  *result = x - y;
285  }
286  return true;
287 #endif
288 }
289 
290 /* Compute the product of two int_fast32_t integers with overflow checking. */
291 inline static bool jas_safe_intfast32_mul(int_fast32_t x, int_fast32_t y,
292  int_fast32_t *result)
293 {
294 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 5)
295  int_fast32_t result_buffer;
296  if (!result)
297  result = &result_buffer;
298  return !__builtin_mul_overflow(x, y, result);
299 #else
300  if (x > 0) {
301  /* x is positive */
302  if (y > 0) {
303  /* x and y are positive */
304  if (x > INT_FAST32_MAX / y) {
305  return false;
306  }
307  } else {
308  /* x positive, y nonpositive */
309  if (y < INT_FAST32_MIN / x) {
310  return false;
311  }
312  }
313  } else {
314  /* x is nonpositive */
315  if (y > 0) {
316  /* x is nonpositive, y is positive */
317  if (x < INT_FAST32_MIN / y) {
318  return false;
319  }
320  } else { /* x and y are nonpositive */
321  if (x != 0 && y < INT_FAST32_MAX / x) {
322  return false;
323  }
324  }
325  }
326 
327  if (result) {
328  *result = x * y;
329  }
330  return true;
331 #endif
332 }
333 
334 /* Compute the product of three int_fast32_t integers with overflow checking. */
335 inline static bool jas_safe_intfast32_mul3(int_fast32_t a, int_fast32_t b,
336  int_fast32_t c, int_fast32_t *result)
337 {
338  int_fast32_t tmp;
339  if (!jas_safe_intfast32_mul(a, b, &tmp) ||
340  !jas_safe_intfast32_mul(tmp, c, &tmp)) {
341  return false;
342  }
343  if (result) {
344  *result = tmp;
345  }
346  return true;
347 }
348 
349 /* Compute the sum of two int_fast32_t integers with overflow checking. */
350 inline static bool jas_safe_intfast32_add(int_fast32_t x, int_fast32_t y,
351  int_fast32_t *result)
352 {
353 #if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 5)
354  int_fast32_t result_buffer;
355  if (!result)
356  result = &result_buffer;
357  return !__builtin_add_overflow(x, y, result);
358 #else
359  if ((y > 0 && x > INT_FAST32_MAX - y) ||
360  (y < 0 && x < INT_FAST32_MIN - y)) {
361  return false;
362  }
363  if (result) {
364  *result = x + y;
365  }
366  return true;
367 #endif
368 }
369 
370 #ifdef __cplusplus
371 }
372 #endif
373 
374 #endif
Primitive Types.