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author | László Langó <llango.u-szeged@partner.samsung.com> | 2016-09-01 12:52:19 +0200 |
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committer | László Langó <llango.u-szeged@partner.samsung.com> | 2016-09-01 14:52:10 +0200 |
commit | 63f739e5a0f64abb4e3d2ed103a2f2813c1f2257 (patch) | |
tree | 23aac9790d76de68f434c8914696c81781d0ff96 | |
parent | a59cbfe1a26e79734b00599850ccb12bb7ee2aa1 (diff) |
Add documentation to port APIv1.0jerryscript-release-1.0.0
JerryScript-DCO-1.0-Signed-off-by: László Langó llango.u-szeged@partner.samsung.com
-rw-r--r-- | docs/05.PORT-API.md | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/docs/05.PORT-API.md b/docs/05.PORT-API.md new file mode 100644 index 00000000..be2ea419 --- /dev/null +++ b/docs/05.PORT-API.md @@ -0,0 +1,210 @@ +# 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 <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 + +```c +#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 + +```c +#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 */ +``` |