[Logs] print size and caps when malloc fails (IDFGH-9267)

[chipweinberger]

Before: Memory allocation failed.

After: Mem alloc fail. size 1600 caps 0x8

When memory allocation fails, we don't get many details. This adds a little bit more info.

I avoided using snprintf, due stack size concerns.

[SoucheSouche]

@chipweinberger Thanks for the update. I will sync the PR if you don't plan on adding more changes.

[chipweinberger]

all good! no more to change.

[SoucheSouche]

@chipweinberger,
There seem to be an issue with this PR. The function fmt_abort_str() needs to placed in RAM as the caller heap_caps_alloc_failed() has to be placed in RAM as well. Unfortunately for us, itoa() is placed in flash on certain boards which makes it impossible to use in fmt_abort_str().

The only viable alternatives I can see here are:

• implement ourselves print_hex() and print_dec() and put them in RAM, and lose available heap
• drop the feature all together.

[chipweinberger]

I'll update the PR. A simple function will suffice for hex.

// print a hex number to a buffer
void shex(char buf[8], uint32_t n) {
    for (int i = 0; i < 8; i++) {
        uint8_t b4 = (n >> 28 - (i * 4)) & 0b1111;
        buf[i] = b4 <= 9 ? '0' + b4 : 'a' + b4 - 10; 
    }
}

[chipweinberger]

updated!

[chipweinberger]

should be all good now. tested it.

[SoucheSouche]

@chipweinberger, I just merged this feature on our gitlab repository. It should be available in master on github in the next sync.

[chipweinberger]

appreciate your work on the PRs. thanks