# Reference ## Termination 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. ```c /** * Signal the port that jerry experienced a fatal failure from which it cannot * recover. * * @param code gives the cause of the error. * * Note: jerry expects the function not to return. * * Example: a libc-based port may implement this with exit() or abort(), or both. */ void jerry_port_fatal (jerry_fatal_code_t code); ``` Error codes ```c typedef enum { ERR_OUT_OF_MEMORY = 10, ERR_SYSCALL = 11, ERR_REF_COUNT_LIMIT = 12, ERR_FAILED_INTERNAL_ASSERTION = 120 } jerry_fatal_code_t; ``` ## I/O These are the only I/O functions jerry calls. ```c /** * Print a string to the console. The function should implement a printf-like * interface, where the first argument specifies a format string on how to * stringify the rest of the parameter list. * * This function is only called with strings coming from the executed ECMAScript * wanting to print something as the result of its normal operation. * * It should be the port that decides what a "console" is. * * Example: a libc-based port may implement this with vprintf(). */ void jerry_port_console (const char *fmt, ...); /** * Jerry log levels. The levels are in severity order * where the most serious levels come first. */ typedef enum { JERRY_LOG_LEVEL_ERROR, /**< the engine will terminate after the message is printed */ JERRY_LOG_LEVEL_WARNING, /**< a request is aborted, but the engine continues its operation */ JERRY_LOG_LEVEL_DEBUG, /**< debug messages from the engine, low volume */ JERRY_LOG_LEVEL_TRACE /**< detailed info about engine internals, potentially high volume */ } jerry_log_level_t; /** * Display or log a debug/error message. The function should implement a printf-like * interface, where the first argument specifies the log level * and the second argument specifies a format string on how to stringify the rest * of the parameter list. * * This function is only called with messages coming from the jerry engine as * the result of some abnormal operation or describing its internal operations * (e.g., data structure dumps or tracing info). * * It should be the port that decides whether error and debug messages are logged to * the console, or saved to a database or to a file. * * Example: a libc-based port may implement this with vfprintf(stderr) or * vfprintf(logfile), or both, depending on log level. */ void jerry_port_log (jerry_log_level_t level, const char *fmt, ...); ``` ## Date ```c /** * Jerry time zone structure */ typedef struct { int offset; /**< minutes from west */ int daylight_saving_time; /**< daylight saving time (1 - DST applies, 0 - not on DST) */ } jerry_time_zone_t; /** * Get timezone and daylight saving data * * @return true - if success * false - otherwise */ bool jerry_port_get_time_zone (jerry_time_zone_t *); /** * Get system time * * @return milliseconds since Unix epoch */ double jerry_port_get_current_time (void); ``` # How to port JerryScript This section describes a basic port implementation which was created for Unix based systems. ## Termination ```c #include #include "jerry-port.h" /** * Default implementation of jerry_port_fatal. */ void jerry_port_fatal (jerry_fatal_code_t code) { exit (code); } /* jerry_port_fatal */ ``` ## I/O ```c #include #include "jerry-port.h" /** * Provide console message implementation for the engine. */ void jerry_port_console (const char *format, /**< format string */ ...) /**< parameters */ { va_list args; va_start (args, format); vfprintf (stdout, format, args); va_end (args); } /* jerry_port_console */ /** * Provide log message implementation for the engine. * * Note: * This example ignores the log level. */ void jerry_port_log (jerry_log_level_t level, /**< log level */ const char *format, /**< format string */ ...) /**< parameters */ { va_list args; va_start (args, format); vfprintf (stderr, format, args); va_end (args); } /* jerry_port_log */ ``` ## Date ```c #include #include "jerry-port.h" /** * Default implementation of jerry_port_get_time_zone. */ bool jerry_port_get_time_zone (jerry_time_zone_t *tz_p) { struct timeval tv; struct timezone tz; /* gettimeofday may not fill tz, so zero-initializing */ tz.tz_minuteswest = 0; tz.tz_dsttime = 0; if (gettimeofday (&tv, &tz) != 0) { return false; } tz_p->offset = tz.tz_minuteswest; tz_p->daylight_saving_time = tz.tz_dsttime > 0 ? 1 : 0; return true; } /* jerry_port_get_time_zone */ /** * Default implementation of jerry_port_get_current_time. */ double jerry_port_get_current_time () { struct timeval tv; if (gettimeofday (&tv, NULL) != 0) { return 0; } return ((double) tv.tv_sec) * 1000.0 + ((double) tv.tv_usec) / 1000.0; } /* jerry_port_get_current_time */ ```