1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef _CHRE_RE_H_ 18 #define _CHRE_RE_H_ 19 20 /** 21 * Some of the core Runtime Environment utilities of the Context Hub 22 * Runtime Environment. 23 * 24 * This includes functions for memory allocation, logging, and timers. 25 */ 26 27 #include <stdarg.h> 28 #include <stdbool.h> 29 #include <stdint.h> 30 #include <stdlib.h> 31 32 #ifdef __cplusplus 33 extern "C" { 34 #endif 35 36 /** 37 * The instance ID for the CHRE. 38 * 39 * This ID is used to identify events generated by the CHRE (as 40 * opposed to events generated by another nanoapp). 41 */ 42 #define CHRE_INSTANCE_ID UINT32_C(0) 43 44 /** 45 * A timer ID representing an invalid timer. 46 * 47 * This valid is returned by chreTimerSet() if a timer cannot be 48 * started. 49 */ 50 #define CHRE_TIMER_INVALID UINT32_C(-1) 51 52 53 54 /** 55 * Logging levels used to indicate severity level of logging messages. 56 * 57 * CHRE_LOG_ERROR: Something fatal has happened, i.e. something that will have 58 * user-visible consequences and won't be recoverable without explicitly 59 * deleting some data, uninstalling applications, wiping the data 60 * partitions or reflashing the entire phone (or worse). 61 * CHRE_LOG_WARN: Something that will have user-visible consequences but is 62 * likely to be recoverable without data loss by performing some explicit 63 * action, ranging from waiting or restarting an app all the way to 64 * re-downloading a new version of an application or rebooting the device. 65 * CHRE_LOG_INFO: Something interesting to most people happened, i.e. when a 66 * situation is detected that is likely to have widespread impact, though 67 * isn't necessarily an error. 68 * CHRE_LOG_DEBUG: Used to further note what is happening on the device that 69 * could be relevant to investigate and debug unexpected behaviors. You 70 * should log only what is needed to gather enough information about what 71 * is going on about your component. 72 * 73 * There is currently no API to turn on/off logging by level, but we anticipate 74 * adding such in future releases. 75 * 76 * @see chreLog 77 */ 78 enum chreLogLevel { 79 CHRE_LOG_ERROR, 80 CHRE_LOG_WARN, 81 CHRE_LOG_INFO, 82 CHRE_LOG_DEBUG 83 }; 84 85 86 87 /** 88 * Get the application ID. 89 * 90 * The application ID is set by the loader of the nanoapp. This is not 91 * assured to be unique among all nanoapps running in the system. 92 * 93 * @returns The application ID. 94 */ 95 uint64_t chreGetAppId(void); 96 97 /** 98 * Get the instance ID. 99 * 100 * The instance ID is the CHRE handle to this nanoapp. This is assured 101 * to be unique among all nanoapps running in the system, and to be 102 * different from the CHRE_INSTANCE_ID. This is the ID used to communicate 103 * between nanoapps. 104 * 105 * @returns The instance ID 106 */ 107 uint32_t chreGetInstanceId(void); 108 109 /** 110 * A method for logging information about the system. 111 * 112 * A log entry can have a variety of levels (@see LogLevel). This function 113 * allows a variable number of arguments, in a printf-style format. 114 * 115 * A nanoapp needs to be able to rely upon consistent printf format 116 * recognition across any platform, and thus we establish formats which 117 * are required to be handled by every CHRE implementation. Some of the 118 * integral formats may seem obscure, but this API heavily uses types like 119 * uint32_t and uint16_t. The platform independent macros for those printf 120 * formats, like PRId32 or PRIx16, end up using some of these "obscure" 121 * formats on some platforms, and thus are required. 122 * 123 * For the initial N release, our emphasis is on correctly getting information 124 * into the log, and minimizing the requirements for CHRE implementations 125 * beyond that. We're not as concerned about how the information is visually 126 * displayed. As a result, there are a number of format sub-specifiers which 127 * are "OPTIONAL" for the N implementation. "OPTIONAL" in this context means 128 * that a CHRE implementation is allowed to essentially ignore the specifier, 129 * but it must understand the specifier enough in order to properly skip it. 130 * 131 * For a nanoapp author, an OPTIONAL format means you might not get exactly 132 * what you want on every CHRE implementation, but you will always get 133 * something sane. 134 * 135 * To be clearer, here's an example with the OPTIONAL 0-padding for integers 136 * for different hypothetical CHRE implementations. 137 * Compliant, chose to implement OPTIONAL format: 138 * chreLog(level, "%04x", 20) ==> "0014" 139 * Compliant, chose not to implement OPTIONAL format: 140 * chreLog(level, "%04x", 20) ==> "14" 141 * Non-compliant, discarded format because the '0' was assumed to be incorrect: 142 * chreLog(level, "%04x", 20) ==> "" 143 * 144 * Note that some of the OPTIONAL specifiers will probably become 145 * required in future APIs. 146 * 147 * We also have NOT_SUPPORTED specifiers. Nanoapp authors should not use any 148 * NOT_SUPPORTED specifiers, as unexpected things could happen on any given 149 * CHRE implementation. A CHRE implementation is allowed to support this 150 * (for example, when using shared code which already supports this), but 151 * nanoapp authors need to avoid these. 152 * 153 * 154 * Unless specifically noted as OPTIONAL or NOT_SUPPORTED, format 155 * (sub-)specifiers listed below are required. 156 * 157 * OPTIONAL format sub-specifiers: 158 * - '-' (left-justify within the given field width) 159 * - '+' (preceed the result with a '+' sign if it is positive) 160 * - ' ' (preceed the result with a blank space if no sign is going to be 161 * output) 162 * - '#' (For 'o', 'x' or 'X', preceed output with "0", "0x" or "0X", 163 * respectively. For floating point, unconditionally output a decimal 164 * point.) 165 * - '0' (left pad the number with zeroes instead of spaces when <width> 166 * needs padding) 167 * - <width> (A number representing the minimum number of characters to be 168 * output, left-padding with blank spaces if needed to meet the 169 * minimum) 170 * - '.'<precision> (A number which has different meaning depending on context.) 171 * - Integer context: Minimum number of digits to output, padding with 172 * leading zeros if needed to meet the minimum. 173 * - 'f' context: Number of digits to output after the decimal 174 * point (to the right of it). 175 * - 's' context: Maximum number of characters to output. 176 * 177 * Integral format specifiers: 178 * - 'd' (signed) 179 * - 'u' (unsigned) 180 * - 'o' (octal) 181 * - 'x' (hexadecimal, lower case) 182 * - 'X' (hexadecimal, upper case) 183 * 184 * Integral format sub-specifiers (as prefixes to an above integral format): 185 * - 'hh' (char) 186 * - 'h' (short) 187 * - 'l' (long) 188 * - 'll' (long long) 189 * - 'z' (size_t) 190 * - 't' (ptrdiff_t) 191 * 192 * Other format specifiers: 193 * - 'f' (floating point) 194 * - 'c' (character) 195 * - 's' (character string, terminated by '\0') 196 * - 'p' (pointer) 197 * - '%' (escaping the percent sign (i.e. "%%" becomes "%")) 198 * 199 * NOT_SUPPORTED specifiers: 200 * - 'n' (output nothing, but fill in a given pointer with the number 201 * of characters written so far) 202 * - '*' (indicates that the width/precision value comes from one of the 203 * arguments to the function) 204 * - 'e', 'E' (scientific notation output) 205 * - 'g', 'G' (Shortest floating point representation) 206 * 207 * @param level The severity level for this message. 208 * @param formatStr Either the entirety of the message, or a printf-style 209 * format string of the format documented above. 210 * @param ... A variable number of arguments necessary for the given 211 * 'formatStr' (there may be no additional arguments for some 'formatStr's). 212 */ 213 void chreLog(enum chreLogLevel level, const char *formatStr, ...); 214 215 /** 216 * Get the system time. 217 * 218 * This returns a time in nanoseconds in reference to some arbitrary 219 * time in the past. This method is only useful for determining timing 220 * between events on the system, and is not useful for determining 221 * any sort of absolute time. 222 * 223 * This value must always increase (and must never roll over). This 224 * value has no meaning across CHRE reboots. 225 * 226 * @returns The system time, in nanoseconds. 227 */ 228 uint64_t chreGetTime(void); 229 230 /** 231 * Set a timer. 232 * 233 * When the timer fires, nanoappHandleEvent will be invoked with 234 * CHRE_EVENT_TIMER and with the given 'cookie'. 235 * 236 * A CHRE implementation is required to provide at least 32 237 * timers. However, there's no assurance there will be any available 238 * for any given nanoapp (if it's loaded late, etc). 239 * 240 * @param duration Time, in nanoseconds, before the timer fires. 241 * @param cookie Argument that will be sent to nanoappHandleEvent upon the 242 * timer firing. This is allowed to be NULL and does not need to be 243 * a valid pointer (assuming the nanoappHandleEvent code is expecting such). 244 * @param oneShot If true, the timer will just fire once. If false, the 245 * timer will continue to refire every 'duration', until this timer is 246 * canceled (@see chreTimerCancel). 247 * 248 * @returns The timer ID. If the system is unable to set a timer 249 * (no more available timers, etc.) then CHRE_TIMER_INVALID will 250 * be returned. 251 * 252 * @see nanoappHandleEvent 253 */ 254 uint32_t chreTimerSet(uint64_t duration, const void* cookie, bool oneShot); 255 256 /** 257 * Cancel a timer. 258 * 259 * After this method returns, the CHRE assures there will be no more 260 * events sent from this timer, and any enqueued events from this timer 261 * will need to be evicted from the queue by the CHRE. 262 * 263 * @param timerId A timer ID obtained by this nanoapp via chreTimerSet(). 264 * @returns true if the timer was cancelled, false otherwise. We may 265 * fail to cancel the timer if it's a one shot which (just) fired, 266 * or if the given timer ID is not owned by the calling app. 267 */ 268 bool chreTimerCancel(uint32_t timerId); 269 270 /** 271 * Terminate this nanoapp. 272 * 273 * This takes effect immediately. 274 * 275 * The CHRE will no longer execute this nanoapp. The CHRE will not invoke 276 * nanoappEnd(), nor will it call any memory free callbacks in the nanoapp. 277 * 278 * The CHRE will unload/evict this nanoapp's code. 279 * 280 * @param abortCode A value indicating the reason for aborting. (Note that 281 * in this version of the API, there is no way for anyone to access this 282 * code, but future APIs may expose it.) 283 * @returns Never. This method does not return, as the CHRE stops nanoapp 284 * execution immediately. 285 */ 286 void chreAbort(uint32_t abortCode); 287 288 /** 289 * Allocate a given number of bytes from the system heap. 290 * 291 * The nanoapp is required to free this memory via chreHeapFree() prior to 292 * the nanoapp ending. 293 * 294 * While the CHRE implementation is required to free up heap resources of 295 * a nanoapp when unloading it, future requirements and tests focused on 296 * nanoapps themselves may check for memory leaks, and will require nanoapps 297 * to properly manage their heap resources. 298 * 299 * @param bytes The number of bytes requested. 300 * @returns A pointer to 'bytes' contiguous bytes of heap memory, or NULL 301 * if the allocation could not be performed. This pointer must be suitably 302 * aligned for any kind of variable. 303 * 304 * @see chreHeapFree. 305 */ 306 void* chreHeapAlloc(uint32_t bytes); 307 308 /** 309 * Free a heap allocation. 310 * 311 * This allocation must be from a value returned from a chreHeapAlloc() call 312 * made by this nanoapp. In other words, it is illegal to free memory 313 * allocated by another nanoapp (or the CHRE). 314 * 315 * @param ptr 'ptr' is required to be a value returned from chreHeapAlloc(). 316 * Note that since chreHeapAlloc can return NULL, CHRE 317 * implementations must safely handle 'ptr' being NULL. 318 * 319 * @see chreHeapAlloc. 320 */ 321 void chreHeapFree(void* ptr); 322 323 324 #ifdef __cplusplus 325 } 326 #endif 327 328 #endif /* _CHRE_RE_H_ */ 329 330