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.
/**
* 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
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.
/**
* 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
/**
* 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
#include <stdlib.h>
#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
#include <stdarg.h>
#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
#include <sys/time.h>
#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 */
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