T-Kernel 2.0 Extension（T2EX）

T-Kernel 2.0 Extension (T2EX)

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●Network Communication

• provides socket interfaces for communication including TCP/IP and UDP/IP
• provides DHCP and DNS client
• provides socket interface API with high degree of compatibility with POSIX specification
• accomplishes resource saving for target embedded devices

○Improvement from POSIX specification

• To avoid excessive abstraction, the API name for socket-related functions has "so_" prefix (to stand for socket).
• If an error occurs, a negative value is returned.
• For the APIs that require timeout, provides APIs that can handle the T-Kernel 2.0 timeout format (TMO, TMO_U) in addition to the APIs of time data format of thePOSIX specification
• Provides so_break() that aborts the ongoing communication forcibly

○Main APIs for network management

• so_socket - Creates an endpoint for communication
• so_accept - Accepts a new connection on a socket
• so_bind - Binds a name to a socket
• so_connect - Connects a socket
• so_listen - Listens for socket connections
• so_select, so_select_ms, so_select_us - Synchronous I/O multiplexing
• so_recvfrom, so_recvmsg - Receives a message from a socket
• so_sendto, so_sendmsg - Sends a message on a socket
• so_gethostname - Gets name of current host
• so_break - Stops socket operation

●File System Support

• supports FAT file system by default
• handles the FAT12, FAT16, and FAT32 file system formats and also uses VFAT long file names
• provides the standard I/O library functions such as fopen() and fprintf()
• provides an API set similar to the file input/output function of the POSIX specification

○Improvement from POSIX specification

• To avoid excessive abstraction, the API name for file-related functions has "fs_" prefix (to stand for file system)
• If an error occurs, a negative value is returned.
• for the APIs that handle timestamps, APIs that can handle the T-Kernel 2.0 time format (SYSTIM, SYSTIM_U) have been provided in addition to the APIs of time data format of the POSIX specification
• supports 64-bit large files
• provides so_break() that aborts the ongoing file operation forcibly
• supports "File System Implementation Part" that is written by users

○Main APIs of file system support

• fs_regist - Registers a file system implementation part
• fs_attach - Connects a file system implementation part
• fs_open - Opens or creates a file
• fs_lseek, fs_lseek64 - Changes the file read/write offset position
• fs_read - Reads from a file
• fs_write - Writes to a file
• s_creat - Creates a file
• fs_truncate, fs_ftruncate, fs_truncate64, fs_ftruncate64 - Truncates or enlarges a file
• fs_sync - Synchronizes the file system
• fs_mkdir - Creates a directory
• fs_break - Stops a file management operation

○File system implementation part

• provides the function for users to independently define program codes that handle a file system
• useful when special devices and/or special file systems for embedded systems are to be handled
  Example 1: FlashROM file system that supports leveling of wearing caused by writing  (wear leveling)
  Example 2: Latest file systems such as exFAT
• manipulation of files through common API from applications
• fs_open(), fs_read(), fs_write(), ...

●Standard C compatible Library

• provides API that is highly compatible with the standard C library (JIS X3010:2003).

○Improvement from the standard C library

• changes the design so that it values the thread-safety because of multi-tasking
• does away with the acquisition of error information by errno, and adopts the method used in T-Kernel.
• eparates the groups of functions that handle the files and the group of functions that handle the sockets.

○Examples of API

• math.h
  log, logf, logl - Natural logarithm function
  sin, sinf, sinl - Sine function
  sqrt, sqrtf, sqrtl - Square root function
• stdio.h
  fprintf, printf, snprintf, sprintf - Formatted output
  fscanf, scanf, sscanf - Formatted input conversion
  fopen, fopen_eno - Opens file
• string.h
  strcmp - Compares two strings
  strcpy - Copies a string

●Calendar

• converts from the system time (SYSTIM, SYSTIM_U) of T-Kernel and the time_t numeric time value, to the representation in characters, or in divided elements, and vice versa.
• API name prefix is "dt_" (date/time).

○Improvement from POSIX specification

• If an error occurs, a negative value is returned.

○Main API

• dt_tzset - Sets time zone conversion information
• dt_localtime, dt_localtime_ms, dt_localtime_us - Converts a time value to a broken-down local time
• dt_strftime - Converts date and time to a string
• dt_strptime - date and time conversion
• mktime_eno, mktime - Converts from element-separated local time to calendar time
• gmtime_r_eno, gmtime_r - Converts from calendar time to element-separated UTC time

●Program Load (original feature of T2EX)

• loads a program and then executes it
• API name prefix is "pm_" (program module).
• uses a file or a memory area as a program module
• provides a sample for building a loaded program module.

○Supports two types of load modules

• a general program ... it executes at the same protection level as the caller
  Used when a division of implementation of application is attempted (lib, plug-in, ...)
• a system program . . .it executes at the special privilege level and  (and provides the system level I/F).
  Enhances OS by providing additional device driver I/F and subsystem I/F.

●Memory Protection (original feature of T2EX)

• provides protection by separation of privilege level and user level
  improves the stability and reliability of the entire system by protecting the memory area used by T-Kernel 2.0, T2EX and system programs such as device drivers, etc. from the user application.
• provides compact and high-speed memory protection to be used by the small information appliances, etc.

○generates a memory protection violation exception when an illegal memory access is attempted, and executes the exception handling function.

• Exception handling in task: TaskMemFaultHdr()
• Exception handling in task independent part: RawMemFaultHdr()

■Please download T-Kernel 2.0 Extension (T2EX)  HERE