Random() is much too slow

[westfw]

Apparently the Arduino trng() function spends most of it's time initializing the R4 SCE, and neither the R4 code nor the Renesas-provided code check whether it has already been initialized

Initializing the SCE drops the random() time to about 20us.

Random function on R4 terribly slow

I get about 98 ms, pretty consistently. (~97900 us, using micros()) The Arduino code for R4 boards reads: static long trng() { uint32_t value[4]; if (HW_SCE_McuSpecificInit() != FSP_SUCCESS) return -1; HW_SCE_RNG_Read(value); return (long)value[0] >= 0 ? value[0] : -value[0]; } Apparently almost ALL of this time is spent in HW_SCE_McuSpecificInit(), which doesn't remember that it has already been initialized! (sigh. Cursed vendor libraries!) The time goes down to 20us. That's …