Standard C Library

The kernel currently provides only the minimal subset of the standard C library required to meet the needs of Zephyr and its subsystems and features, primarily in the areas of string manipulation and display.

Applications that require a more extensive C library can either submit contributions that enhance the existing library or substitute with a replacement library.

The Zephyr SDK and other supported toolchains comes with a bare-metal C library based on newlib that can be used with Zephyr by selecting the CONFIG_NEWLIB_LIBC in the application configuration file. Part of the support for newlib is a set of hooks available under lib/libc/newlib/libc-hooks.c which integrates the c library with basic kernel services.

Minimal C Library

The minimal C library is part of Zephyr and provides a minimal set of C functions needed by Zephyr.

The following functions are implemented in the minimal C library included with Zephyr:

• abs()

• atoi()

• bsearch()

• calloc()

• free()

• gmtime()

• gmtime_r()

• isalnum()

• isalpha()

• isdigit()

• isgraph()

• isprint()

• isspace()

• isupper()

• isxdigit()

• localtime()

• malloc()

• memchr()

• memcmp()

• memcpy()

• memmove()

• memset()

• mktime()

• rand()

• realloc()

• snprintf()

• sprintf()

• strcat()

• strchr()

• strcmp()

• strcpy()

• strlen()

• trncat()

• strncmp()

• strncpy()

• strrchr()

• strstr()

• strtol()

• trtoul()

• time()

• tolower()

• toupper()

• vsnprintf()

• vsprintf()