Pedro Correia / mbed-dev

mbed library sources. Supersedes mbed-src.

Fork of mbed-dev by mbed official

platform/critical.h@149:156823d33999, 2016-10-28 (annotated)

Committer:
<>
Date:
Fri Oct 28 11:17:30 2016 +0100
Revision:
149:156823d33999
Child:
160:d5399cc887bb
This updates the lib to the mbed lib v128



NOTE: This release includes a restructuring of the file and directory locations and thus some

include paths in your code may need updating accordingly.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 149:156823d33999 1
<> 149:156823d33999 2 /** \addtogroup platform */
<> 149:156823d33999 3 /** @{*/
<> 149:156823d33999 4 /*
<> 149:156823d33999 5 * Copyright (c) 2015-2016, ARM Limited, All Rights Reserved
<> 149:156823d33999 6 * SPDX-License-Identifier: Apache-2.0
<> 149:156823d33999 7 *
<> 149:156823d33999 8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
<> 149:156823d33999 9 * not use this file except in compliance with the License.
<> 149:156823d33999 10 * You may obtain a copy of the License at
<> 149:156823d33999 11 *
<> 149:156823d33999 12 * http://www.apache.org/licenses/LICENSE-2.0
<> 149:156823d33999 13 *
<> 149:156823d33999 14 * Unless required by applicable law or agreed to in writing, software
<> 149:156823d33999 15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
<> 149:156823d33999 16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 149:156823d33999 17 * See the License for the specific language governing permissions and
<> 149:156823d33999 18 * limitations under the License.
<> 149:156823d33999 19 */
<> 149:156823d33999 20
<> 149:156823d33999 21 #ifndef __MBED_UTIL_CRITICAL_H__
<> 149:156823d33999 22 #define __MBED_UTIL_CRITICAL_H__
<> 149:156823d33999 23
<> 149:156823d33999 24 #include <stdbool.h>
<> 149:156823d33999 25 #include <stdint.h>
<> 149:156823d33999 26 #include <stddef.h>
<> 149:156823d33999 27
<> 149:156823d33999 28 #ifdef __cplusplus
<> 149:156823d33999 29 extern "C" {
<> 149:156823d33999 30 #endif
<> 149:156823d33999 31
<> 149:156823d33999 32
<> 149:156823d33999 33 /** Determine the current interrupts enabled state
<> 149:156823d33999 34 *
<> 149:156823d33999 35 * This function can be called to determine whether or not interrupts are currently enabled.
<> 149:156823d33999 36 * \note
<> 149:156823d33999 37 * NOTE:
<> 149:156823d33999 38 * This function works for both cortex-A and cortex-M, although the underlyng implementation
<> 149:156823d33999 39 * differs.
<> 149:156823d33999 40 * @return true if interrupts are enabled, false otherwise
<> 149:156823d33999 41 */
<> 149:156823d33999 42 bool core_util_are_interrupts_enabled(void);
<> 149:156823d33999 43
<> 149:156823d33999 44 /** Mark the start of a critical section
<> 149:156823d33999 45 *
<> 149:156823d33999 46 * This function should be called to mark the start of a critical section of code.
<> 149:156823d33999 47 * \note
<> 149:156823d33999 48 * NOTES:
<> 149:156823d33999 49 * 1) The use of this style of critical section is targetted at C based implementations.
<> 149:156823d33999 50 * 2) These critical sections can be nested.
<> 149:156823d33999 51 * 3) The interrupt enable state on entry to the first critical section (of a nested set, or single
<> 149:156823d33999 52 * section) will be preserved on exit from the section.
<> 149:156823d33999 53 * 4) This implementation will currently only work on code running in privileged mode.
<> 149:156823d33999 54 */
<> 149:156823d33999 55 void core_util_critical_section_enter(void);
<> 149:156823d33999 56
<> 149:156823d33999 57 /** Mark the end of a critical section
<> 149:156823d33999 58 *
<> 149:156823d33999 59 * This function should be called to mark the end of a critical section of code.
<> 149:156823d33999 60 * \note
<> 149:156823d33999 61 * NOTES:
<> 149:156823d33999 62 * 1) The use of this style of critical section is targetted at C based implementations.
<> 149:156823d33999 63 * 2) These critical sections can be nested.
<> 149:156823d33999 64 * 3) The interrupt enable state on entry to the first critical section (of a nested set, or single
<> 149:156823d33999 65 * section) will be preserved on exit from the section.
<> 149:156823d33999 66 * 4) This implementation will currently only work on code running in privileged mode.
<> 149:156823d33999 67 */
<> 149:156823d33999 68 void core_util_critical_section_exit(void);
<> 149:156823d33999 69
<> 149:156823d33999 70 /**
<> 149:156823d33999 71 * Atomic compare and set. It compares the contents of a memory location to a
<> 149:156823d33999 72 * given value and, only if they are the same, modifies the contents of that
<> 149:156823d33999 73 * memory location to a given new value. This is done as a single atomic
<> 149:156823d33999 74 * operation. The atomicity guarantees that the new value is calculated based on
<> 149:156823d33999 75 * up-to-date information; if the value had been updated by another thread in
<> 149:156823d33999 76 * the meantime, the write would fail due to a mismatched expectedCurrentValue.
<> 149:156823d33999 77 *
<> 149:156823d33999 78 * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
<> 149:156823d33999 79 * you to the article on compare-and swap].
<> 149:156823d33999 80 *
<> 149:156823d33999 81 * @param ptr The target memory location.
<> 149:156823d33999 82 * @param[in,out] expectedCurrentValue A pointer to some location holding the
<> 149:156823d33999 83 * expected current value of the data being set atomically.
<> 149:156823d33999 84 * The computed 'desiredValue' should be a function of this current value.
<> 149:156823d33999 85 * @Note: This is an in-out parameter. In the
<> 149:156823d33999 86 * failure case of atomic_cas (where the
<> 149:156823d33999 87 * destination isn't set), the pointee of expectedCurrentValue is
<> 149:156823d33999 88 * updated with the current value.
<> 149:156823d33999 89 * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
<> 149:156823d33999 90 *
<> 149:156823d33999 91 * @return true if the memory location was atomically
<> 149:156823d33999 92 * updated with the desired value (after verifying
<> 149:156823d33999 93 * that it contained the expectedCurrentValue),
<> 149:156823d33999 94 * false otherwise. In the failure case,
<> 149:156823d33999 95 * exepctedCurrentValue is updated with the new
<> 149:156823d33999 96 * value of the target memory location.
<> 149:156823d33999 97 *
<> 149:156823d33999 98 * pseudocode:
<> 149:156823d33999 99 * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
<> 149:156823d33999 100 * if *p != *old {
<> 149:156823d33999 101 * *old = *p
<> 149:156823d33999 102 * return false
<> 149:156823d33999 103 * }
<> 149:156823d33999 104 * *p = new
<> 149:156823d33999 105 * return true
<> 149:156823d33999 106 * }
<> 149:156823d33999 107 *
<> 149:156823d33999 108 * @Note: In the failure case (where the destination isn't set), the value
<> 149:156823d33999 109 * pointed to by expectedCurrentValue is still updated with the current value.
<> 149:156823d33999 110 * This property helps writing concise code for the following incr:
<> 149:156823d33999 111 *
<> 149:156823d33999 112 * function incr(p : pointer to int, a : int) returns int {
<> 149:156823d33999 113 * done = false
<> 149:156823d33999 114 * value = *p // This fetch operation need not be atomic.
<> 149:156823d33999 115 * while not done {
<> 149:156823d33999 116 * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
<> 149:156823d33999 117 * }
<> 149:156823d33999 118 * return value + a
<> 149:156823d33999 119 * }
<> 149:156823d33999 120 */
<> 149:156823d33999 121 bool core_util_atomic_cas_u8(uint8_t *ptr, uint8_t *expectedCurrentValue, uint8_t desiredValue);
<> 149:156823d33999 122
<> 149:156823d33999 123 /**
<> 149:156823d33999 124 * Atomic compare and set. It compares the contents of a memory location to a
<> 149:156823d33999 125 * given value and, only if they are the same, modifies the contents of that
<> 149:156823d33999 126 * memory location to a given new value. This is done as a single atomic
<> 149:156823d33999 127 * operation. The atomicity guarantees that the new value is calculated based on
<> 149:156823d33999 128 * up-to-date information; if the value had been updated by another thread in
<> 149:156823d33999 129 * the meantime, the write would fail due to a mismatched expectedCurrentValue.
<> 149:156823d33999 130 *
<> 149:156823d33999 131 * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
<> 149:156823d33999 132 * you to the article on compare-and swap].
<> 149:156823d33999 133 *
<> 149:156823d33999 134 * @param ptr The target memory location.
<> 149:156823d33999 135 * @param[in,out] expectedCurrentValue A pointer to some location holding the
<> 149:156823d33999 136 * expected current value of the data being set atomically.
<> 149:156823d33999 137 * The computed 'desiredValue' should be a function of this current value.
<> 149:156823d33999 138 * @Note: This is an in-out parameter. In the
<> 149:156823d33999 139 * failure case of atomic_cas (where the
<> 149:156823d33999 140 * destination isn't set), the pointee of expectedCurrentValue is
<> 149:156823d33999 141 * updated with the current value.
<> 149:156823d33999 142 * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
<> 149:156823d33999 143 *
<> 149:156823d33999 144 * @return true if the memory location was atomically
<> 149:156823d33999 145 * updated with the desired value (after verifying
<> 149:156823d33999 146 * that it contained the expectedCurrentValue),
<> 149:156823d33999 147 * false otherwise. In the failure case,
<> 149:156823d33999 148 * exepctedCurrentValue is updated with the new
<> 149:156823d33999 149 * value of the target memory location.
<> 149:156823d33999 150 *
<> 149:156823d33999 151 * pseudocode:
<> 149:156823d33999 152 * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
<> 149:156823d33999 153 * if *p != *old {
<> 149:156823d33999 154 * *old = *p
<> 149:156823d33999 155 * return false
<> 149:156823d33999 156 * }
<> 149:156823d33999 157 * *p = new
<> 149:156823d33999 158 * return true
<> 149:156823d33999 159 * }
<> 149:156823d33999 160 *
<> 149:156823d33999 161 * @Note: In the failure case (where the destination isn't set), the value
<> 149:156823d33999 162 * pointed to by expectedCurrentValue is still updated with the current value.
<> 149:156823d33999 163 * This property helps writing concise code for the following incr:
<> 149:156823d33999 164 *
<> 149:156823d33999 165 * function incr(p : pointer to int, a : int) returns int {
<> 149:156823d33999 166 * done = false
<> 149:156823d33999 167 * value = *p // This fetch operation need not be atomic.
<> 149:156823d33999 168 * while not done {
<> 149:156823d33999 169 * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
<> 149:156823d33999 170 * }
<> 149:156823d33999 171 * return value + a
<> 149:156823d33999 172 * }
<> 149:156823d33999 173 */
<> 149:156823d33999 174 bool core_util_atomic_cas_u16(uint16_t *ptr, uint16_t *expectedCurrentValue, uint16_t desiredValue);
<> 149:156823d33999 175
<> 149:156823d33999 176 /**
<> 149:156823d33999 177 * Atomic compare and set. It compares the contents of a memory location to a
<> 149:156823d33999 178 * given value and, only if they are the same, modifies the contents of that
<> 149:156823d33999 179 * memory location to a given new value. This is done as a single atomic
<> 149:156823d33999 180 * operation. The atomicity guarantees that the new value is calculated based on
<> 149:156823d33999 181 * up-to-date information; if the value had been updated by another thread in
<> 149:156823d33999 182 * the meantime, the write would fail due to a mismatched expectedCurrentValue.
<> 149:156823d33999 183 *
<> 149:156823d33999 184 * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
<> 149:156823d33999 185 * you to the article on compare-and swap].
<> 149:156823d33999 186 *
<> 149:156823d33999 187 * @param ptr The target memory location.
<> 149:156823d33999 188 * @param[in,out] expectedCurrentValue A pointer to some location holding the
<> 149:156823d33999 189 * expected current value of the data being set atomically.
<> 149:156823d33999 190 * The computed 'desiredValue' should be a function of this current value.
<> 149:156823d33999 191 * @Note: This is an in-out parameter. In the
<> 149:156823d33999 192 * failure case of atomic_cas (where the
<> 149:156823d33999 193 * destination isn't set), the pointee of expectedCurrentValue is
<> 149:156823d33999 194 * updated with the current value.
<> 149:156823d33999 195 * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
<> 149:156823d33999 196 *
<> 149:156823d33999 197 * @return true if the memory location was atomically
<> 149:156823d33999 198 * updated with the desired value (after verifying
<> 149:156823d33999 199 * that it contained the expectedCurrentValue),
<> 149:156823d33999 200 * false otherwise. In the failure case,
<> 149:156823d33999 201 * exepctedCurrentValue is updated with the new
<> 149:156823d33999 202 * value of the target memory location.
<> 149:156823d33999 203 *
<> 149:156823d33999 204 * pseudocode:
<> 149:156823d33999 205 * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
<> 149:156823d33999 206 * if *p != *old {
<> 149:156823d33999 207 * *old = *p
<> 149:156823d33999 208 * return false
<> 149:156823d33999 209 * }
<> 149:156823d33999 210 * *p = new
<> 149:156823d33999 211 * return true
<> 149:156823d33999 212 * }
<> 149:156823d33999 213 *
<> 149:156823d33999 214 * @Note: In the failure case (where the destination isn't set), the value
<> 149:156823d33999 215 * pointed to by expectedCurrentValue is still updated with the current value.
<> 149:156823d33999 216 * This property helps writing concise code for the following incr:
<> 149:156823d33999 217 *
<> 149:156823d33999 218 * function incr(p : pointer to int, a : int) returns int {
<> 149:156823d33999 219 * done = false
<> 149:156823d33999 220 * value = *p // This fetch operation need not be atomic.
<> 149:156823d33999 221 * while not done {
<> 149:156823d33999 222 * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
<> 149:156823d33999 223 * }
<> 149:156823d33999 224 * return value + a
<> 149:156823d33999 225 * }
<> 149:156823d33999 226 */
<> 149:156823d33999 227 bool core_util_atomic_cas_u32(uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue);
<> 149:156823d33999 228
<> 149:156823d33999 229 /**
<> 149:156823d33999 230 * Atomic compare and set. It compares the contents of a memory location to a
<> 149:156823d33999 231 * given value and, only if they are the same, modifies the contents of that
<> 149:156823d33999 232 * memory location to a given new value. This is done as a single atomic
<> 149:156823d33999 233 * operation. The atomicity guarantees that the new value is calculated based on
<> 149:156823d33999 234 * up-to-date information; if the value had been updated by another thread in
<> 149:156823d33999 235 * the meantime, the write would fail due to a mismatched expectedCurrentValue.
<> 149:156823d33999 236 *
<> 149:156823d33999 237 * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
<> 149:156823d33999 238 * you to the article on compare-and swap].
<> 149:156823d33999 239 *
<> 149:156823d33999 240 * @param ptr The target memory location.
<> 149:156823d33999 241 * @param[in,out] expectedCurrentValue A pointer to some location holding the
<> 149:156823d33999 242 * expected current value of the data being set atomically.
<> 149:156823d33999 243 * The computed 'desiredValue' should be a function of this current value.
<> 149:156823d33999 244 * @Note: This is an in-out parameter. In the
<> 149:156823d33999 245 * failure case of atomic_cas (where the
<> 149:156823d33999 246 * destination isn't set), the pointee of expectedCurrentValue is
<> 149:156823d33999 247 * updated with the current value.
<> 149:156823d33999 248 * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
<> 149:156823d33999 249 *
<> 149:156823d33999 250 * @return true if the memory location was atomically
<> 149:156823d33999 251 * updated with the desired value (after verifying
<> 149:156823d33999 252 * that it contained the expectedCurrentValue),
<> 149:156823d33999 253 * false otherwise. In the failure case,
<> 149:156823d33999 254 * exepctedCurrentValue is updated with the new
<> 149:156823d33999 255 * value of the target memory location.
<> 149:156823d33999 256 *
<> 149:156823d33999 257 * pseudocode:
<> 149:156823d33999 258 * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
<> 149:156823d33999 259 * if *p != *old {
<> 149:156823d33999 260 * *old = *p
<> 149:156823d33999 261 * return false
<> 149:156823d33999 262 * }
<> 149:156823d33999 263 * *p = new
<> 149:156823d33999 264 * return true
<> 149:156823d33999 265 * }
<> 149:156823d33999 266 *
<> 149:156823d33999 267 * @Note: In the failure case (where the destination isn't set), the value
<> 149:156823d33999 268 * pointed to by expectedCurrentValue is still updated with the current value.
<> 149:156823d33999 269 * This property helps writing concise code for the following incr:
<> 149:156823d33999 270 *
<> 149:156823d33999 271 * function incr(p : pointer to int, a : int) returns int {
<> 149:156823d33999 272 * done = false
<> 149:156823d33999 273 * value = *p // This fetch operation need not be atomic.
<> 149:156823d33999 274 * while not done {
<> 149:156823d33999 275 * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
<> 149:156823d33999 276 * }
<> 149:156823d33999 277 * return value + a
<> 149:156823d33999 278 * }
<> 149:156823d33999 279 */
<> 149:156823d33999 280 bool core_util_atomic_cas_ptr(void **ptr, void **expectedCurrentValue, void *desiredValue);
<> 149:156823d33999 281
<> 149:156823d33999 282 /**
<> 149:156823d33999 283 * Atomic increment.
<> 149:156823d33999 284 * @param valuePtr Target memory location being incremented.
<> 149:156823d33999 285 * @param delta The amount being incremented.
<> 149:156823d33999 286 * @return The new incremented value.
<> 149:156823d33999 287 */
<> 149:156823d33999 288 uint8_t core_util_atomic_incr_u8(uint8_t *valuePtr, uint8_t delta);
<> 149:156823d33999 289
<> 149:156823d33999 290 /**
<> 149:156823d33999 291 * Atomic increment.
<> 149:156823d33999 292 * @param valuePtr Target memory location being incremented.
<> 149:156823d33999 293 * @param delta The amount being incremented.
<> 149:156823d33999 294 * @return The new incremented value.
<> 149:156823d33999 295 */
<> 149:156823d33999 296 uint16_t core_util_atomic_incr_u16(uint16_t *valuePtr, uint16_t delta);
<> 149:156823d33999 297
<> 149:156823d33999 298 /**
<> 149:156823d33999 299 * Atomic increment.
<> 149:156823d33999 300 * @param valuePtr Target memory location being incremented.
<> 149:156823d33999 301 * @param delta The amount being incremented.
<> 149:156823d33999 302 * @return The new incremented value.
<> 149:156823d33999 303 */
<> 149:156823d33999 304 uint32_t core_util_atomic_incr_u32(uint32_t *valuePtr, uint32_t delta);
<> 149:156823d33999 305
<> 149:156823d33999 306 /**
<> 149:156823d33999 307 * Atomic increment.
<> 149:156823d33999 308 * @param valuePtr Target memory location being incremented.
<> 149:156823d33999 309 * @param delta The amount being incremented in bytes.
<> 149:156823d33999 310 * @return The new incremented value.
<> 149:156823d33999 311 *
<> 149:156823d33999 312 * @note The type of the pointer argument is not taken into account
<> 149:156823d33999 313 * and the pointer is incremented by bytes.
<> 149:156823d33999 314 */
<> 149:156823d33999 315 void *core_util_atomic_incr_ptr(void **valuePtr, ptrdiff_t delta);
<> 149:156823d33999 316
<> 149:156823d33999 317 /**
<> 149:156823d33999 318 * Atomic decrement.
<> 149:156823d33999 319 * @param valuePtr Target memory location being decremented.
<> 149:156823d33999 320 * @param delta The amount being decremented.
<> 149:156823d33999 321 * @return The new decremented value.
<> 149:156823d33999 322 */
<> 149:156823d33999 323 uint8_t core_util_atomic_decr_u8(uint8_t *valuePtr, uint8_t delta);
<> 149:156823d33999 324
<> 149:156823d33999 325 /**
<> 149:156823d33999 326 * Atomic decrement.
<> 149:156823d33999 327 * @param valuePtr Target memory location being decremented.
<> 149:156823d33999 328 * @param delta The amount being decremented.
<> 149:156823d33999 329 * @return The new decremented value.
<> 149:156823d33999 330 */
<> 149:156823d33999 331 uint16_t core_util_atomic_decr_u16(uint16_t *valuePtr, uint16_t delta);
<> 149:156823d33999 332
<> 149:156823d33999 333 /**
<> 149:156823d33999 334 * Atomic decrement.
<> 149:156823d33999 335 * @param valuePtr Target memory location being decremented.
<> 149:156823d33999 336 * @param delta The amount being decremented.
<> 149:156823d33999 337 * @return The new decremented value.
<> 149:156823d33999 338 */
<> 149:156823d33999 339 uint32_t core_util_atomic_decr_u32(uint32_t *valuePtr, uint32_t delta);
<> 149:156823d33999 340
<> 149:156823d33999 341 /**
<> 149:156823d33999 342 * Atomic decrement.
<> 149:156823d33999 343 * @param valuePtr Target memory location being decremented.
<> 149:156823d33999 344 * @param delta The amount being decremented in bytes.
<> 149:156823d33999 345 * @return The new decremented value.
<> 149:156823d33999 346 *
<> 149:156823d33999 347 * @note The type of the pointer argument is not taken into account
<> 149:156823d33999 348 * and the pointer is decremented by bytes
<> 149:156823d33999 349 */
<> 149:156823d33999 350 void *core_util_atomic_decr_ptr(void **valuePtr, ptrdiff_t delta);
<> 149:156823d33999 351
<> 149:156823d33999 352 #ifdef __cplusplus
<> 149:156823d33999 353 } // extern "C"
<> 149:156823d33999 354 #endif
<> 149:156823d33999 355
<> 149:156823d33999 356
<> 149:156823d33999 357 #endif // __MBED_UTIL_CRITICAL_H__
<> 149:156823d33999 358
<> 149:156823d33999 359 /** @}*/