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improve efficiency of stm32 random gen

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This commit is contained in:
Lucian Copeland 2020-08-26 18:47:19 -04:00
parent 05bde255f7
commit c229345741
1 changed files with 9 additions and 4 deletions
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13
ports/stm/common-hal/os/__init__.c
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@ -72,15 +72,20 @@ bool common_hal_os_urandom(uint8_t *buffer, uint32_t length) {
if (HAL_RNG_Init(&handle) != HAL_OK) mp_raise_ValueError(translate("RNG Init Error"));
//Assign bytes
for (uint i = 0; i < length; i++) {
uint32_t temp;
uint32_t i = 0;
while (i < length) {
uint32_t new_random;
uint32_t start = HAL_GetTick();
//the HAL function has a timeout, but it isn't long enough, and isn't adjustable
while(!(__HAL_RNG_GET_FLAG(&handle,RNG_FLAG_DRDY)) && ((HAL_GetTick() - start) < RNG_TIMEOUT));
if (HAL_RNG_GenerateRandomNumber(&handle, &temp) != HAL_OK) {
if (HAL_RNG_GenerateRandomNumber(&handle, &new_random) != HAL_OK) {
mp_raise_ValueError(translate("Random number generation error"));
}
buffer[i] = (uint8_t)temp;
for (int j = 0; j < 4 && i < length; j++) {
buffer[i] = new_random & 0xff;
i++;
new_random >>= 8;
}
}
//shut down the peripheral