Doxygen Documentation: string.h #27

[seekaddo]

Doxygen documentation for the functions in string.h. I have already tested it.

PN: I added errno setting for some of the functions, like strdup when an error occurs. We don't have malloc implemented yet and also errno. I added it for feature. We can also remove it for now to prevent confusion and later make a new PR for the new changes in those methods.

errno and malloc.

The strdup function makes a call to malloc in its implementation. I was wondering which malloc is that then since can't use the normal libc malloc for Embedded. Can we implement a simple wrapper malloc for this? With just a simple ringbuffer to a static array.

All kinds of Feedback and suggestions are welcome.

[phillipjohnston]

Regarding malloc: It's actually implemented in libmemory. Malloc implementations are very situation-dependent and can vary widely depending on whether you're using a PC, bare metal firmware, or an RTOS. I have kept malloc separate to account for that fact. I think the documentation for malloc should still be included here because it is technically a libc function.

I will eventually make it a submodule, but I have not yet architected a good way to include it in the build system. I'll be thinking more about that in the coming weeks.

Regarding errno: Leaving the notes in is fine, as I do plan on adding support (#6)

Thanks again for your great help!

[seekaddo]

@phillipjohnston oh ok. Then everything will be great. Thanks for the explanation. Yea with the errno I was thinking about how to implement it to support both sterrorr() and others. I was thinking of using enum for defining all the type errno's EINVAL ... etc. and a static string array enum {EINVAL,....} errn; extern errn errno;

static const char *const MALLOC = {"Each malloc interpretation in strings"} 

Something like this I have in mind.