furi_hal_random returns values when RNG output is not ready

[n1kolasM]

Describe the bug.

furi_hal_random does not check error and ready conditions of random generators and returns empty generator output.

Reproduction

Fill buffer of size at least 40 bytes with furi_hal_random_fill_bufand view it somehow(e. g. print on screen), 8 bytes of the buffer are filled with zeroes

Target

Flipper Zero

Logs

No response

Anything else?

In #2569 logic of error checks of random generator was changed.

• Before furi_hal_random waited for ready state (DRDY=1) and crashed on error conditions (CECS=1 or SECS=1)
• After furi_hal_random waits for (DRDY=1 or CECS=0 or SECS=0)

I think valid condition to sample random (DRDY=1 and CECS=0 and SECS=0) and valid condition for furi_hal_random_read_rng is

while(LL_RNG_IsActiveFlag_CECS(RNG) || LL_RNG_IsActiveFlag_SECS(RNG) ||
          !LL_RNG_IsActiveFlag_DRDY(RNG)) {
    // error check logic
}

[n1kolasM]

Simple app code for checking random output in gist