|
| 1 | +--- |
| 2 | +layout: page |
| 3 | +title: Port API |
| 4 | +permalink: /port-api/ |
| 5 | +--- |
| 6 | + |
| 7 | +* toc |
| 8 | +{:toc} |
| 9 | + |
| 10 | +# Reference |
| 11 | + |
| 12 | +## Termination |
| 13 | + |
| 14 | +It is questionable whether a library should be able to terminate an application. Any API function can signal an error (ex.: cannot allocate memory), so the engine use the termination approach with this port function. |
| 15 | + |
| 16 | +```c |
| 17 | +/** |
| 18 | + * Signal the port that jerry experienced a fatal failure from which it cannot |
| 19 | + * recover. |
| 20 | + * |
| 21 | + * @param code gives the cause of the error. |
| 22 | + * |
| 23 | + * Note: jerry expects the function not to return. |
| 24 | + * |
| 25 | + * Example: a libc-based port may implement this with exit() or abort(), or both. |
| 26 | + */ |
| 27 | +void jerry_port_fatal (jerry_fatal_code_t code); |
| 28 | +``` |
| 29 | +
|
| 30 | +Error codes |
| 31 | +
|
| 32 | +```c |
| 33 | +typedef enum |
| 34 | +{ |
| 35 | + ERR_OUT_OF_MEMORY = 10, |
| 36 | + ERR_SYSCALL = 11, |
| 37 | + ERR_REF_COUNT_LIMIT = 12, |
| 38 | + ERR_FAILED_INTERNAL_ASSERTION = 120 |
| 39 | +} jerry_fatal_code_t; |
| 40 | +``` |
| 41 | + |
| 42 | +## I/O |
| 43 | + |
| 44 | +These are the only I/O functions jerry calls. |
| 45 | + |
| 46 | +```c |
| 47 | +/** |
| 48 | + * Print a string to the console. The function should implement a printf-like |
| 49 | + * interface, where the first argument specifies a format string on how to |
| 50 | + * stringify the rest of the parameter list. |
| 51 | + * |
| 52 | + * This function is only called with strings coming from the executed ECMAScript |
| 53 | + * wanting to print something as the result of its normal operation. |
| 54 | + * |
| 55 | + * It should be the port that decides what a "console" is. |
| 56 | + * |
| 57 | + * Example: a libc-based port may implement this with vprintf(). |
| 58 | + */ |
| 59 | +void jerry_port_console (const char *fmt, ...); |
| 60 | + |
| 61 | +/** |
| 62 | + * Jerry log levels. The levels are in severity order |
| 63 | + * where the most serious levels come first. |
| 64 | + */ |
| 65 | +typedef enum |
| 66 | +{ |
| 67 | + JERRY_LOG_LEVEL_ERROR, /**< the engine will terminate after the message is printed */ |
| 68 | + JERRY_LOG_LEVEL_WARNING, /**< a request is aborted, but the engine continues its operation */ |
| 69 | + JERRY_LOG_LEVEL_DEBUG, /**< debug messages from the engine, low volume */ |
| 70 | + JERRY_LOG_LEVEL_TRACE /**< detailed info about engine internals, potentially high volume */ |
| 71 | +} jerry_log_level_t; |
| 72 | + |
| 73 | +/** |
| 74 | + * Display or log a debug/error message. The function should implement a printf-like |
| 75 | + * interface, where the first argument specifies the log level |
| 76 | + * and the second argument specifies a format string on how to stringify the rest |
| 77 | + * of the parameter list. |
| 78 | + * |
| 79 | + * This function is only called with messages coming from the jerry engine as |
| 80 | + * the result of some abnormal operation or describing its internal operations |
| 81 | + * (e.g., data structure dumps or tracing info). |
| 82 | + * |
| 83 | + * It should be the port that decides whether error and debug messages are logged to |
| 84 | + * the console, or saved to a database or to a file. |
| 85 | + * |
| 86 | + * Example: a libc-based port may implement this with vfprintf(stderr) or |
| 87 | + * vfprintf(logfile), or both, depending on log level. |
| 88 | + */ |
| 89 | +void jerry_port_log (jerry_log_level_t level, const char *fmt, ...); |
| 90 | +``` |
| 91 | +
|
| 92 | +## Date |
| 93 | +
|
| 94 | +```c |
| 95 | +/** |
| 96 | + * Jerry time zone structure |
| 97 | + */ |
| 98 | +typedef struct |
| 99 | +{ |
| 100 | + int offset; /**< minutes from west */ |
| 101 | + int daylight_saving_time; /**< daylight saving time (1 - DST applies, 0 - not on DST) */ |
| 102 | +} jerry_time_zone_t; |
| 103 | +
|
| 104 | +/** |
| 105 | + * Get timezone and daylight saving data |
| 106 | + * |
| 107 | + * @return true - if success |
| 108 | + * false - otherwise |
| 109 | + */ |
| 110 | +bool jerry_port_get_time_zone (jerry_time_zone_t *); |
| 111 | +
|
| 112 | +/** |
| 113 | + * Get system time |
| 114 | + * |
| 115 | + * @return milliseconds since Unix epoch |
| 116 | + */ |
| 117 | +double jerry_port_get_current_time (void); |
| 118 | +``` |
| 119 | + |
| 120 | +# How to port JerryScript |
| 121 | + |
| 122 | +This section describes a basic port implementation which was created for Unix based systems. |
| 123 | + |
| 124 | +## Termination |
| 125 | + |
| 126 | +```c |
| 127 | +#include <stdlib.h> |
| 128 | +#include "jerry-port.h" |
| 129 | + |
| 130 | +/** |
| 131 | + * Default implementation of jerry_port_fatal. |
| 132 | + */ |
| 133 | +void jerry_port_fatal (jerry_fatal_code_t code) |
| 134 | +{ |
| 135 | + exit (code); |
| 136 | +} /* jerry_port_fatal */ |
| 137 | +``` |
| 138 | +
|
| 139 | +## I/O |
| 140 | +
|
| 141 | +```c |
| 142 | +#include <stdarg.h> |
| 143 | +#include "jerry-port.h" |
| 144 | +
|
| 145 | +/** |
| 146 | + * Provide console message implementation for the engine. |
| 147 | + */ |
| 148 | +void |
| 149 | +jerry_port_console (const char *format, /**< format string */ |
| 150 | + ...) /**< parameters */ |
| 151 | +{ |
| 152 | + va_list args; |
| 153 | + va_start (args, format); |
| 154 | + vfprintf (stdout, format, args); |
| 155 | + va_end (args); |
| 156 | +} /* jerry_port_console */ |
| 157 | +
|
| 158 | +/** |
| 159 | + * Provide log message implementation for the engine. |
| 160 | + * |
| 161 | + * Note: |
| 162 | + * This example ignores the log level. |
| 163 | + */ |
| 164 | +void |
| 165 | +jerry_port_log (jerry_log_level_t level, /**< log level */ |
| 166 | + const char *format, /**< format string */ |
| 167 | + ...) /**< parameters */ |
| 168 | +{ |
| 169 | + va_list args; |
| 170 | + va_start (args, format); |
| 171 | + vfprintf (stderr, format, args); |
| 172 | + va_end (args); |
| 173 | +} /* jerry_port_log */ |
| 174 | +``` |
| 175 | + |
| 176 | +## Date |
| 177 | + |
| 178 | +```c |
| 179 | +#include <sys/time.h> |
| 180 | +#include "jerry-port.h" |
| 181 | + |
| 182 | +/** |
| 183 | + * Default implementation of jerry_port_get_time_zone. |
| 184 | + */ |
| 185 | +bool jerry_port_get_time_zone (jerry_time_zone_t *tz_p) |
| 186 | +{ |
| 187 | + struct timeval tv; |
| 188 | + struct timezone tz; |
| 189 | + |
| 190 | + /* gettimeofday may not fill tz, so zero-initializing */ |
| 191 | + tz.tz_minuteswest = 0; |
| 192 | + tz.tz_dsttime = 0; |
| 193 | + |
| 194 | + if (gettimeofday (&tv, &tz) != 0) |
| 195 | + { |
| 196 | + return false; |
| 197 | + } |
| 198 | + |
| 199 | + tz_p->offset = tz.tz_minuteswest; |
| 200 | + tz_p->daylight_saving_time = tz.tz_dsttime > 0 ? 1 : 0; |
| 201 | + |
| 202 | + return true; |
| 203 | +} /* jerry_port_get_time_zone */ |
| 204 | + |
| 205 | +/** |
| 206 | + * Default implementation of jerry_port_get_current_time. |
| 207 | + */ |
| 208 | +double jerry_port_get_current_time () |
| 209 | +{ |
| 210 | + struct timeval tv; |
| 211 | + |
| 212 | + if (gettimeofday (&tv, NULL) != 0) |
| 213 | + { |
| 214 | + return 0; |
| 215 | + } |
| 216 | + |
| 217 | + return ((double) tv.tv_sec) * 1000.0 + ((double) tv.tv_usec) / 1000.0; |
| 218 | +} /* jerry_port_get_current_time */ |
| 219 | +``` |
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