Getting Hard Faults when GDISP_NEED_TEXT_WORDWRAP is enabled

[kengineer]

It seems that I'm getting some hard faults upon setting GDISP_NEED_TEXT_WORDWRAP to true. I'm still working on figuring out the exact cause, but it appears it's when I do anything related to drawing labels, specifically in this function call:

 

static bool mf_countline_callback(mf_str line, uint16_t count, void *state) {
	int *linecount = (int*)state;
	(*linecount)++;

	return TRUE;
}

The fault specifically happens immediately after calling (*linecount)++;

 

Still looking into this but was wondering if anyone had any advice. FYI I'm using uGFX v2.4

[kengineer]

I think I figured it out, there's a bug here.

In mf_countline_callback, you are casting the void pointer as an int type which technically would vary by platform (int32_t on my platform).

 

IF you go up a couple of function calls, you'll find:

mf_wordwrap(font, cx, str, mf_countline_callback, &nbrLines);

Where nbrLines is defined as a uint16_t.

This is the problem, you're passing a uint16_t pointer in this case, and casting it as a 32 (at least on this platform) resulting in not incrementing the same part of memory we think we are. Upon modifying this, I don't get a hard fault anymore, so I'm going to see if the text wrap actually works now. Please verify this and move to the bug reports area.

[kengineer]

Just confirmed, so here's the fix:

static bool mf_countline_callback(mf_str line, uint16_t count, void *state) {
	uint16_t *linecount = (uint16_t*)state;
	(*linecount)++;

	return TRUE;
}

 

[Joel Bodenmann]

Thank you very much for bringing this to our attention and providing a corresponding patch. We just applied the patch to the repository: https://git.ugfx.io/uGFX/uGFX/commit/b9b555eae26a539ee71b30668f8e3fdb343e6ac1

Update: Blog post: