newlib missing C library functions

gary_metalle — Tue, 29 Jan 2019 16:18:10 GMT

I'm using newlib with an imxrt1050.

The SDK provides various different flavours of newlib (nano, semihost etc) for the platform I am using but it has missing standard 'C' functions such as time and clock. There's also a random number generator hardware on-chip and I would have expected this to have been hooked into std:random_device. There are probably lots of other examples of missing hooks that I would have expected to have been supported in this library for SOC?

Maybe there's a list somewhere of the functions that are supported or even a document explaining how to properly get these hooks? I have actually wrapped the time function and called the appropriate board function to read the RTC, so it is possible.

Re: newlib missing C library functions

danielholala — Thu, 31 Jan 2019 10:19:47 GMT

Hi Gary,

the documentation on newlib that I use is the documentation included in MCUExpesso IDE (Menu Help > Help contents and then in the left pane Tools > Newlib > Newlib C Library).

I'm afraid that you'll have to peruse the documentation of each 'C' function you plan to use and check whether it requires additional supporting subroutines, e.g. for time():

Regarding time(), also see this old discussion here: time () does nothing

MCUXpresso IDE中的主题 Re: newlib missing C library functions

newlib missing C library functions

Re: newlib missing C library functions