C Library (libc)

Introduction to LIBC

The LIBC (C library) provided by RT-Thread consists of three parts: the compiler built-in LIBC leveling layer and the POSIX layer. The layout is shown in the following figure:

1 LIBC Balancing Layer

The LIBC balancing layer is responsible for docking the underlying stub functions of the built-in LIBC of the compiler toolchain and balancing the differences in the implementation of the built-in LIBC API of different compilers. It provides a unified functional interface for the upper POSIX layer and is located in the components/libc/compiler file directory. Balancing is required because the standard C library functions provided by the built-in LIBC of the four compilation toolchains GCC (newlib), Keil-MDK, IAR, and Visual Studio (WIN32) have different levels of support. The LIBC balancing layer is responsible for balancing the standard C libraries provided by the four different compilation chains to the same level. The LIBC balancing layer does not require manual intervention by the user. It will automatically perform balancing according to the compilation platform and toolchain used by the user when compiling the project. It ensures that the upper layer does not need to distinguish which compilation platform and toolchain LIBC is used, and can use a common header file to reference the relevant functions of LIBC.

2 ISO/ANSI C Standard

ANSI C, ISO C, Standard C refers to the standard for the C language published by the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO). Historically, this name was used exclusively to refer to the original and best-supported version of this standard (called C89 or C90). Software developers using C are encouraged to follow the requirements of the standard because it encourages the use of cross-platform code. The first standard for C was published by ANSI. Although this document was later adopted by the International Organization for Standardization (ISO) and the revisions published by ISO were also adopted by ANSI, the name ANSI C (rather than ISO C) is still widely used. Some software developers use the name ISO C, while others use the neutral name Standard C. For example, the commonly mentioned C89 (ANSI X3.159-1989), C99 (ISO/IEC 9899:1999), and C11 (ISO/IEC 9899:2011) actually refer to different versions of the standard.

This standard is usually supported by the built-in LIBC of the compiler/toolchain. For example, the built-in LIBC provided by Keil-MDK, IAR, etc. all meet this standard.

3 POSIX Standard

Portable Operating System Interface (POSIX) is the general name of a series of interrelated standards that define APIs for running software on various UNIX operating systems. Its official name is IEEE Std 1003, and its international standard name is ISO/IEC 9945. ISO/ANSI C is a subset of POSIX.

3.1 IEEE Std 1003.1

For LIBC, the widely used POSIX standard is the 1003.1 standard, whose full name is IEEE Std 1003.1 (abbreviated as POSIX.1). IEEE Std 1003.1-2001, IEEE Std 1003.1-2008, etc. are the updated versions of POSIX.1 released at different times.

3.2 IEEE Std. 1003.13

This standard is POSIX's real-time profile. This standard is a subset of IEEE Std 1003.1. IEEE Std. 1003.13 defines four subsets:

  • Minimal: Minimal Embedded Subset Specification - PSE51

  • Controller: Industrial Controller Subset Specification - PSE52

  • Dedicated: A larger subset of embedded systems specifications - PSE53

  • Multi-Purpose: A subset specification for large-scale general-purpose systems with real-time requirements - PSE54

Currently, RT-Thread has implemented the PSE51 specification and part of the PSE52 specification.

3.3 POSIX Standard and RT-Thread Implementation

File

API

PSE51

PSE52

PSE53

PSE54

RT-Thread

<ctype.h>

isalnum()

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isalpha()

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isblank()

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iscntrl()

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isdigit()

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isgraph()

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islower()

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isprint()

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ispunct()

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isspace()

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isupper()

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isxdigit()

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tolower()

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toupper()

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<errno.h>

errno

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<fcntl.h>

open()

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creat()

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fcntl()

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posix_fadvise()

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posix_fallocate()

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<fenv.h>

feclearexcept()

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fegetenv()

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fegetexceptflag()

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fegetround()

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feholdexcept()

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feraiseexcept()

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fesetenv()

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fesetexceptflag()

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fesetround()

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fetestexcept()

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feupdateenv()

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<inttypes.h>

imaxabs()

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imaxdiv()

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strtoimax()

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strtoumax()

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wcstoimax()

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wcstoumax()

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<locale.h>

localeconv()

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setlocale()

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<pthread.h>

pthread_attr_destroy()

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pthread_attr_getdetachstate()

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pthread_attr_getguardsize()

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pthread_attr_getinheritsched()

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pthread_attr_getschedparam()

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pthread_attr_getschedpolicy()

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pthread_attr_getscope()

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pthread_attr_getstack()

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pthread_attr_getstackaddr()

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pthread_attr_getstacksize()

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pthread_attr_init()

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pthread_attr_setdetachstate()

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pthread_attr_setguardsize()

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pthread_attr_setinheritsched()

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pthread_attr_setschedparam()

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pthread_attr_setschedpolicy()

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pthread_attr_setscope()

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pthread_attr_setstack()

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pthread_attr_setstackaddr()

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pthread_attr_setstacksize()

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pthread_cancel()

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pthread_cleanup_pop()

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pthread_cleanup_push()

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pthread_cond_broadcast()

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pthread_cond_destroy()

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pthread_cond_init()

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pthread_cond_signal()

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pthread_cond_timedwait()

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pthread_cond_wait()

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pthread_condattr_destroy()

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pthread_condattr_getclock()

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pthread_condattr_init()

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pthread_condattr_setclock()

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pthread_create()

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pthread_detach()

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pthread_equal()

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pthread_exit()

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pthread_getconcurrency()

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pthread_getschedparam()

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pthread_getspecific()

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pthread_join()

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pthread_key_create()

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pthread_key_delete()

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pthread_mutex_destroy()

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pthread_mutex_getprioceiling()

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pthread_mutex_init()

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pthread_mutex_lock()

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pthread_mutex_setprioceiling()

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pthread_mutex_trylock()

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pthread_mutex_unlock()

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pthread_mutexattr_destroy()

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pthread_mutexattr_getprioceiling()

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pthread_mutexattr_getprotocol()

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pthread_mutexattr_gettype()

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pthread_mutexattr_init()

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pthread_mutexattr_setprioceiling()

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pthread_mutexattr_setprotocol()

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pthread_mutexattr_settype()

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pthread_once()

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pthread_self()

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pthread_setcancelstate()

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pthread_setcanceltype()

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pthread_setconcurrency()

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pthread_setschedparam()

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pthread_setschedprio()

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pthread_setspecific()

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pthread_testcancel()

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pthread_atfork()

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pthread_getcpuclockid()

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pthread_condattr_getpshared()

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pthread_condattr_setpshared()

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pthread_mutexattr_getpshared()

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pthread_mutexattr_setpshared()

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<sched.h>

sched_get_priority_max()

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sched_get_priority_min()

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sched_rr_get_interval()

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sched_yield()

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sched_getparam()

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sched_getscheduler()

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sched_setparam()

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sched_setscheduler()

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<semaphore.h>

sem_close()

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sem_destroy()

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sem_getvalue()

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sem_init()

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sem_open()

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sem_post()

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sem_timedwait()

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sem_trywait()

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sem_unlink()

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sem_wait()

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<setjmp.h>

longjmp()

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setjmp()

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siglongjmp()

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sigsetjmp()

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<signal.h>

kill()

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pthread_kill()

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pthread_sigmask()

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raise()

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sigaction()

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sigaddset()

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sigdelset()

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sigemptyset()

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sigfillset()

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sigismember()

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signal()

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sigpending()

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sigprocmask()

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sigqueue()

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sigsuspend()

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sigtimedwait()

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sigwait()

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sigwaitinfo()

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<stdarg.h>

va_arg()

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va_copy()

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va_end()

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va_start()

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<stdio.h>

clearerr()

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fclose()

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fdopen()

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feof()

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ferror()

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fflush()

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fgetc()

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fgets()

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fileno()

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flockfile()

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fopen()

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fprintf()

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fputc()

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fputs()

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fread()

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freopen()

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fscanf()

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ftrylockfile()

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funlockfile()

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fwrite()

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getc()

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getc_unlocked()

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getchar()

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getchar_unlocked()

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gets()

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perror()

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printf()

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putc()

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putc_unlocked()

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putchar()

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putchar_unlocked()

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puts()

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scanf()

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setbuf()

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setvbuf()

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snprintf()

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sprintf()

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sscanf()

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stderr

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stdin

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stdout

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ungetc()

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vfprintf()

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vfscanf()

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vprintf()

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vscanf()

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vsnprintf()

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vsprintf()

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vsscanf()

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fgetpos()

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fseek()

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fseeko()

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fsetpos()

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ftell()

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ftello()

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remove()

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rename()

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rewind()

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tmpfile()

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tmpnam()

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ctermid()

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pclose()

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popen()

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<stdlib.h>

abort()

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abs()

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atof()

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atoi()

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atol()

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atoll()

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bsearch()

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calloc()

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div()

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free()

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getenv()

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labs()

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ldiv()

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llabs()

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lldiv()

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malloc()

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mktime()

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qsort()

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rand()

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rand_r()

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realloc()

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setenv()

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srand()

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strtod()

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strtof()

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strtol()

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strtold()

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strtoll()

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strtoul()

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strtoull()

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unsetenv()

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_Exit()

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atexit()

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exit()

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mblen()

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mbstowcs()

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mbtowc()

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posix_memalign()

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wcstombs()

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wctomb()

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system()

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<string.h>

memchr()

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memcmp()

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memcpy()

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memmove()

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memset()

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strcat()

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strchr()

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strcmp()

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strcoll()

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strcpy()

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strcspn()

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strerror()

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strerror_r()

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strlen()

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strncat()

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strncmp()

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strncpy()

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strpbrk()

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strrchr()

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strspn()

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strstr()

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strtok()

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strtok_r()

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strxfrm()

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<sys/mman.h>

mlockall()

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mmap()

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munlock()

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munmap()

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shm_open()

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shm_unlink()

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msync()

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mprotect()

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posix_madvise()

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<sys/utsname.h>

uname()

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<time.h>

asctime()

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asctime_r()

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clock_getres()

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clock_gettime()

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clock_nanosleep()

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clock_settime()

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√

ctime()

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ctime_r()

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difftime()

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gmtime()

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gmtime_r()

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localtime()

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localtime_r()

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nanosleep()

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strftime()

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time()

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√

timer_create()

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√

timer_delete()

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√

timer_getoverrun()

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√

timer_gettime()

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√

timer_settime()

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*

*

*

√

tzname

*

*

*

*

√

tzset()

*

*

*

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√

clock()

*

*

√

clock_getcpuclockid()

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*

<unistd.h>

alarm()

*

*

*

√

close()

*

*

*

*

√

Environ

*

*

*

*

√

fdatasync()

*

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fsync()

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√

pause()

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√

read()

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√

sysconf()

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√

write()

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confstr()

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access()

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√

chdir()

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√

dup()

*

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dup2()

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fpathconf()

*

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ftruncate()

*

*

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getcwd()

*

*

*

√

link()

*

*

*

lseek()

*

*

*

√

pathconf()

*

*

*

rmdir()

*

*

*

√

unlink()

*

*

*

√

_exit()

*

*

gethostname()

*

*

getpgrp()

*

*

getpid()

*

*

√

getppid()

*

*

√

pipe()

*

*

√

setsid()

*

*

sleep()

*

*

√

execl()

*

*

execle()

*

*

execlp()

*

*

execv()

*

*

execve()

*

*

execvp()

*

*

fork()

*

*

chown()

*

fchown()

*

getegid()

*

geteuid()

*

getgid()

*

getgroups()

*

getlogin()

*

getlogin_r()

*

getopt()

*

getuid()

*

isatty()

*

optarg

*

opterr

*

optind

*

optopt

*

readlink()

*

setegid()

*

seteuid()

*

setgid()

*

setpgid()

*

setuid()

*

symlink()

*

tcgetpgrp()

*

tcsetpgrp()

*

ttyname()

*

ttyname_r()

*

<complex.h>

cabs()

*

*

*

cabsf()

*

*

*

cabsl()

*

*

*

cacos()

*

*

*

cacosf()

*

*

*

cacosh()

*

*

*

cacoshf()

*

*

*

cacoshl()

*

*

*

cacosl()

*

*

*

carg()

*

*

*

cargf()

*

*

*

cargl()

*

*

*

casin()

*

*

*

casinf()

*

*

*

casinh()

*

*

*

casinhf()

*

*

*

casinhl()

*

*

*

casinl()

*

*

*

catan()

*

*

*

catanf()

*

*

*

catanh()

*

*

*

catanhf()

*

*

*

catanhl()

*

*

*

catanl()

*

*

*

ccos()

*

*

*

ccosf()

*

*

*

ccosh()

*

*

*

ccoshf()

*

*

*

ccoshl()

*

*

*

ccosl()

*

*

*

cexp()

*

*

*

cexpf()

*

*

*

cexpl()

*

*

*

cimag()

*

*

*

cimagf()

*

*

*

cimagl()

*

*

*

clog()

*

*

*

clogf()

*

*

*

clogl()

*

*

*

conj()

*

*

*

conjf()

*

*

*

conjl()

*

*

*

cpow()

*

*

*

cpowf()

*

*

*

cpowl()

*

*

*

cproj()

*

*

*

cprojf()

*

*

*

cprojl()

*

*

*

creal()

*

*

*

crealf()

*

*

*

creall()

*

*

*

csin()

*

*

*

csinf()

*

*

*

csinh()

*

*

*

csinhf()

*

*

*

csinhl()

*

*

*

csinl()

*

*

*

csqrt()

*

*

*

csqrtf()

*

*

*

csqrtl()

*

*

*

ctan()

*

*

*

ctanf()

*

*

*

ctanh()

*

*

*

ctanhf()

*

*

*

ctanhl()

*

*

*

ctanl()

*

*

*

<dirent.h>

closedir()

*

*

*

√

opendir()

*

*

*

√

readdir()

*

*

*

√

readdir_r()

*

*

*

√

rewinddir()

*

*

*

√

<math.h>

acos()

*

*

*

acosf()

*

*

*

acosh()

*

*

*

acoshf()

*

*

*

acoshl()

*

*

*

acosl()

*

*

*

asin()

*

*

*

asinf()

*

*

*

asinh()

*

*

*

asinhf()

*

*

*

asinhl()

*

*

*

asinl()

*

*

*

atan()

*

*

*

atan2()

*

*

*

atan2f()

*

*

*

atan2l()

*

*

*

atanf()

*

*

*

atanh()

*

*

*

atanhf()

*

*

*

atanhl()

*

*

*

atanl()

*

*

*

cbrt()

*

*

*

cbrtf()

*

*

*

cbrtl()

*

*

*

ceil()

*

*

*

ceilf()

*

*

*

ceill()

*

*

*

copysign()

*

*

*

copysignf()

*

*

*

copysignl()

*

*

*

cos()

*

*

*

cosf()

*

*

*

cosh()

*

*

*

coshf()

*

*

*

coshl()

*

*

*

cosl()

*

*

*

erf()

*

*

*

erfc()

*

*

*

erfcf()

*

*

*

erfcl()

*

*

*

erff()

*

*

*

erfl()

*

*

*

exp()

*

*

*

exp2()

*

*

*

exp2f()

*

*

*

exp2l()

*

*

*

expf()

*

*

*

expl()

*

*

*

expm1()

*

*

*

expm1f()

*

*

*

expm1l()

*

*

*

fabs()

*

*

*

fabsf()

*

*

*

fabsl()

*

*

*

fdim()

*

*

*

fdimf()

*

*

*

fdiml()

*

*

*

floor()

*

*

*

floorf()

*

*

*

floorl()

*

*

*

fma()

*

*

*

fmaf()

*

*

*

fmal()

*

*

*

fmax()

*

*

*

fmaxf()

*

*

*

fmaxl()

*

*

*

fmin()

*

*

*

fminf()

*

*

*

fminl()

*

*

*

fmod()

*

*

*

fmodf()

*

*

*

fmodl()

*

*

*

fpclassify()

*

*

*

frexp()

*

*

*

frexpf()

*

*

*

frexpl()

*

*

*

hypot()

*

*

*

hypotf()

*

*

*

hypotl()

*

*

*

ilogb()

*

*

*

ilogbf()

*

*

*

ilogbl()

*

*

*

isfinite()

*

*

*

isgreater()

*

*

*

isgreaterequal()

*

*

*

isinf()

*

*

*

isless()

*

*

*

islessequal()

*

*

*

islessgreater()

*

*

*

isnan()

*

*

*

isnormal()

*

*

*

isunordered()

*

*

*

ldexp()

*

*

*

ldexpf()

*

*

*

ldexpl()

*

*

*

lgamma()

*

*

*

lgammaf()

*

*

*

lgammal()

*

*

*

llrint()

*

*

*

llrintf()

*

*

*

llrintl()

*

*

*

llround()

*

*

*

llroundf()

*

*

*

llroundl()

*

*

*

log()

*

*

*

log10()

*

*

*

log10f()

*

*

*

log10l()

*

*

*

log1p()

*

*

*

log1pf()

*

*

*

log1pl()

*

*

*

log2()

*

*

*

log2f()

*

*

*

log2l()

*

*

*

logb()

*

*

*

logbf()

*

*

*

logbl()

*

*

*

logf()

*

*

*

logl()

*

*

*

lrint()

*

*

*

lrintf()

*

*

*

lrintl()

*

*

*

lround()

*

*

*

lroundf()

*

*

*

lroundl()

*

*

*

modf()

*

*

*

modff()

*

*

*

modfl()

*

*

*

nan()

*

*

*

nanf()

*

*

*

nanl()

*

*

*

nearbyint()

*

*

*

nearbyintf()

*

*

*

nearbyintl()

*

*

*

nextafter()

*

*

*

nextafterf()

*

*

*

nextafterl()

*

*

*

nexttoward()

*

*

*

nexttowards()

*

*

*

pow()

*

*

*

powf()

*

*

*

powl()

*

*

*

remainder()

*

*

*

remainderf()

*

*

*

remainderl()

*

*

*

remquo()

*

*

*

remquof()

*

*

*

remquol()

*

*

*

rint()

*

*

*

rintf()

*

*

*

rintl()

*

*

*

round()

*

*

*

roundf()

*

*

*

roundl()

*

*

*

scalbln()

*

*

*

scalblnf()

*

*

*

scalblnl()

*

*

*

scalbn()

*

*

*

scalbnf()

*

*

*

scalbnl()

*

*

*

sin()

*

*

*

sinf()

*

*

*

sinh()

*

*

*

sinhf()

*

*

*

sinhl()

*

*

*

sinl()

*

*

*

sqrt()

*

*

*

sqrtf()

*

*

*

sqrtl()

*

*

*

tan()

*

*

*

tanf()

*

*

*

tanh()

*

*

*

tanhf()

*

*

*

tanhl()

*

*

*

tanl()

*

*

*

tgamma()

*

*

*

tgammaf()

*

*

*

tgammal()

*

*

*

trunc()

*

*

*

truncf()

*

*

*

truncl()

*

*

*

nexttowardf()

*

*

*

signbit()

*

*

*

<mqueue.h>

mq_close()

*

*

*

√

mq_getattr()

*

*

*

mq_notify()

*

*

*

√

mq_open()

*

*

*

√

mq_receive()

*

*

*

√

mq_send()

*

*

*

√

mq_setattr()

*

*

*

mq_timedreceive()

*

*

*

mq_timedsend()

*

*

*

√

mq_unlink()

*

*

*

√

<sys/stat.h>

fstat()

*

*

*

√

mkdir()

*

*

*

√

stat()

*

*

*

√

chmod()

*

fchmod()

*

lstat()

*

mkfifo()

*

umask()

*

<trace.h>

posix_trace_attr_destroy()

*

*

*

posix_trace_attr_getclockres()

*

*

*

posix_trace_attr_getcreatetime()

*

*

*

posix_trace_attr_getgenversion()

*

*

*

posix_trace_attr_getinherited()

*

*

*

posix_trace_attr_getlogfullpolicy()

*

*

*

posix_trace_attr_getlogsize()

*

*

*

posix_trace_attr_getmaxdatasize()

*

*

*

posix_trace_attr_getmaxsystemeventsize()

*

*

*

posix_trace_attr_getmaxusereventsize()

*

*

*

posix_trace_attr_getname()

*

*

*

posix_trace_attr_getstreamfullpolicy()

*

*

*

posix_trace_attr_getstreamsize()

*

*

*

posix_trace_attr_init()

*

*

*

posix_trace_attr_setinherited()

*

*

*

posix_trace_attr_setlogfullpolicy()

*

*

*

posix_trace_attr_setlogsize()

*

*

*

posix_trace_attr_setmaxdatasize()

*

*

*

posix_trace_attr_setname()

*

*

*

posix_trace_attr_setstreamfullpolicy()

*

*

*

posix_trace_attr_setstreamsize()

*

*

*

posix_trace_clear()

*

*

*

posix_trace_close()

*

*

*

posix_trace_create()

*

*

*

posix_trace_create_withlog()

*

*

*

posix_trace_event()

*

*

*

posix_trace_eventid_equal()

*

*

*

posix_trace_eventid_get_name()

*

*

*

posix_trace_eventid_open()

*

*

*

posix_trace_eventset_add()

*

*

*

posix_trace_eventset_del()

*

*

*

posix_trace_eventset_empty()

*

*

*

posix_trace_eventset_fill()

*

*

*

posix_trace_eventset_ismember()

*

*

*

posix_trace_eventtypelist_getnext_id()

*

*

*

posix_trace_eventtypelist_rewind()

*

*

*

posix_trace_flush()

*

*

*

posix_trace_get_attr()

*

*

*

posix_trace_get_filter()

*

*

*

posix_trace_get_status()

*

*

*

posix_trace_getnext_event()

*

*

*

posix_trace_open()

*

*

*

posix_trace_rewind()

*

*

*

posix_trace_set_filter()

*

*

*

posix_trace_shutdown()

*

*

*

posix_trace_start()

*

*

*

posix_trace_stop()

*

*

*

posix_trace_timedgetnext_event()

*

*

*

posix_trace_trid_eventid_open()

*

*

*

posix_trace_trygetnext_event()

*

*

*

<utime.h>

utime()

*

*

*

<aio.h>

aio_cancel()

*

*

√

aio_error()

*

*

√

aio_fsync()

*

*

√

aio_read()

*

*

√

aio_return()

*

*

√

aio_write()

*

*

√

aio_suspend()

*

*

√

lio_listio()

*

*

√

<arpa/inet.h>

htonl()

*

*

√

htons()

*

*

√

inet_addr()

*

*

√

inet_ntoa()

*

*

√

inet_ntop()

*

*

√

inet_pton()

*

*

√

ntohl()

*

*

√

ntohs()

*

*

√

<assert.h>

assert()

*

*

√

<net/if.h>

if_freenameindex()

*

*

√

if_indextoname()

*

*

√

if_nameindex()

*

*

√

if_nametoindex()

*

*

√

<netdb.h>

endhostent()

*

*

endnetent()

*

*

endprotoent()

*

*

endservent()

*

*

freeaddrinfo()

*

*

√

gai_strerror()

*

*

√

getaddrinfo()

*

*

√

gethostent()

*

*

√

getnameinfo()

*

*

√

getnetbyaddr()

*

*

√

getnetbyname()

*

*

getnetent()

*

*

getprotobyname()

*

*

getprotobynumber()

*

*

getprotoent()

*

*

getservbyname()

*

*

getservbyport()

*

*

getservent()

*

*

sethostent()

*

*

setnetent()

*

*

setprotoent()

*

*

setservent()

*

*

<spawn.h>

posix_spawn()

*

*

posix_spawn_file_actions_addclose()

*

*

posix_spawn_file_actions_adddup2()

*

*

posix_spawn_file_actions_addopen()

*

*

posix_spawn_file_actions_destroy()

*

*

posix_spawn_file_actions_init()

*

*

posix_spawnattr_destroy()

*

*

posix_spawnattr_getflags()

*

*

posix_spawnattr_getpgroup()

*

*

posix_spawnattr_getschedparam()

*

*

posix_spawnattr_getschedpolicy()

*

*

posix_spawnattr_getsigdefault()

*

*

posix_spawnattr_getsigmask()

*

*

posix_spawnattr_init()

*

*

posix_spawnattr_setflags()

*

*

posix_spawnattr_setpgroup()

*

*

posix_spawnattr_setschedparam()

*

*

posix_spawnattr_setschedpolicy()

*

*

posix_spawnattr_setsigdefault()

*

*

posix_spawnattr_setsigmask()

*

*

posix_spawnp()

*

*

<sys/select.h>

FD_CLR()

*

*

√

FD_ISSET()

*

*

√

FD_SET()

*

*

√

FD_ZERO()

*

*

√

select()

*

*

√

pselect()

*

*

<sys/socket.h>

accept()

*

*

√

bind()

*

*

√

connect()

*

*

√

getpeername()

*

*

√

getsockname()

*

*

√

getsockopt()

*

*

√

listen()

*

*

√

recv()

*

*

√

recvfrom()

*

*

√

recvmsg()

*

*

send()

*

*

√

sendmsg()

*

*

sendto()

*

*

√

setsockopt()

*

*

√

shutdown()

*

*

√

socket()

*

*

√

socketpair()

*

*

sockatmark()

*

*

<sys/time.h>

times()

*

*

utimes()

*

*

<sys/wait.h>

wait()

*

*

<dlfcn.h>

dlclose()

*

dlerror()

*

dlopen()

*

dlsym()

*

<fnmatch.h>

fnmatch()

*

<glob.h>

glob()

*

globfree()

*

<grp.h>

getgrgid()

*

getgrgid_r()

*

getgrnam()

*

getgrnam_r()

*

<pwd.h>

getpwnam()

*

getpwnam_r()

*

getpwuid()

*

getpwuid_r()

*

<regex.h>

regcomp()

*

regerror()

*

regexec()

*

regfree()

*

<syslog.h>

closelog()

*

openlog()

*

setlogmask()

*

syslog()

*

<termios.h>

cfgetispeed()

*

cfgettospeed()

*

cfsetispeed()

*

cfsettospeed()

*

tcdrain()

*

tcflow()

*

tcflush()

*

tcgetattr()

*

tcsendbreak()

*

tcsetattr()

*

<wchar.h>

btowc()

*

fgetwc()

*

fgetws()

*

fputwc()

*

fputws()

*

fwide()

*

fwprintf()

*

fwscanf()

*

getwc()

*

getwchar()

*

mbrlen()

*

mbrtowc()

*

mbsinit()

*

mbsrtowcs()

*

putwc()

*

putwchar()

*

swprintf()

*

swscanf()

*

ungetwc()

*

vfwprintf()

*

vfwscanf()

*

vswprintf()

*

vswscanf()

*

vwprintf()

*

vwscanf()

*

wcrtomb()

*

wcscat()

*

wcschr()

*

wcscmp()

*

wcscoll()

*

wcscpy()

*

wcscspn()

*

wcsftime()

*

wcslen()

*

wcsncat()

*

wcsncmp()

*

wcsncpy()

*

wcspbrk()

*

wcsrchr()

*

wcsrtombs()

*

wcsspn()

*

wcsstr()

*

wcstod()

*

wcstof()

*

wcstok()

*

wcstol()

*

wcstold()

*

wcstoll()

*

wcstoul()

*

wcstoull()

*

wcsxfrm()

*

wctob()

*

wmemchr()

*

wmemcmp()

*

wmemcpy()

*

wmemmove()

*

wmemset()

*

wprintf()

*

wscanf()

*

<wctype.h>

iswalnum()

*

iswalpha()

*

iswblank()

*

iswcntrl()

*

iswctype()

*

iswdigit()

*

iswgraph()

*

iswlower()

*

iswprint()

*

iswpunct()

*

iswspace()

*

iswupper()

*

iswxdigit()

*

towctrans()

*

towlower()

*

towupper()

*

wctrans()

*

wctype()

*

<wordexp.h>

wordexp()

*

wordfree()

*

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Assoc. Prof. Wiroon Sriborrirux, Founder of Advance Innovation Center (AIC) and Bangsaen Design House (BDH), Electrical Engineering Department, Faculty of Engineering, Burapha University