This section describes target-dependent ISO C library functions. Implementation of these ISO standard functions depends entirely on the target operating system.

Table 5.17 lists all the target-dependent functions. None of these functions is used internally by the library. So if any of these functions are not implemented, only those applications that call the function directly will fail.

The default implementation of these functions is semihosted. That is, each function uses semihosting.

clock() and _clock_init() must be re-implemented together or not at all.