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stm32/rng: Simplify RNG implementation by accessing raw peripheral regs.

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It saves code size and RAM, and is more efficient to execute.
This commit is contained in:
Damien George 2018-02-02 18:22:57 +11:00
parent 762db9ad2f
commit 57d2ac1300
4 changed files with 21 additions and 34 deletions
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1
ports/stm32/Makefile
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@ -265,7 +265,6 @@ SRC_HAL = $(addprefix $(HAL_DIR)/Src/stm32$(MCU_SERIES)xx_,\
hal_pwr_ex.c \
hal_rcc.c \
hal_rcc_ex.c \
hal_rng.c \
hal_rtc.c \
hal_rtc_ex.c \
hal_sd.c \

4
ports/stm32/main.c
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@ -552,10 +552,6 @@ soft_reset:
can_init0();
#endif
#if MICROPY_HW_ENABLE_RNG
rng_init0();
#endif
#if MICROPY_HW_ENABLE_HW_I2C
i2c_init0();
#endif

47
ports/stm32/rng.c
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@ -3,7 +3,7 @@
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
* Copyright (c) 2013-2018 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
@ -24,44 +24,35 @@
* THE SOFTWARE.
*/
#include <string.h>
#include "py/obj.h"
#include "rng.h"
#if MICROPY_HW_ENABLE_RNG
/// \moduleref pyb
STATIC RNG_HandleTypeDef RNGHandle = {.Instance = NULL};
void rng_init0(void) {
// reset the RNG handle
memset(&RNGHandle, 0, sizeof(RNG_HandleTypeDef));
RNGHandle.Instance = RNG;
}
void rng_init(void) {
__RNG_CLK_ENABLE();
HAL_RNG_Init(&RNGHandle);
}
#define RNG_TIMEOUT_MS (10)
uint32_t rng_get(void) {
if (RNGHandle.State == HAL_RNG_STATE_RESET) {
rng_init();
// Enable the RNG peripheral if it's not already enabled
if (!(RNG->CR & RNG_CR_RNGEN)) {
__HAL_RCC_RNG_CLK_ENABLE();
RNG->CR |= RNG_CR_RNGEN;
}
return HAL_RNG_GetRandomNumber(&RNGHandle);
// Wait for a new random number to be ready, takes on the order of 10us
uint32_t start = HAL_GetTick();
while (!(RNG->SR & RNG_SR_DRDY)) {
if (HAL_GetTick() - start >= RNG_TIMEOUT_MS) {
return 0;
}
}
// Get and return the new random number
return RNG->DR;
}
/// \function rng()
/// Return a 30-bit hardware generated random number.
// Return a 30-bit hardware generated random number.
STATIC mp_obj_t pyb_rng_get(void) {
if (RNGHandle.State == HAL_RNG_STATE_RESET) {
rng_init();
}
return mp_obj_new_int(HAL_RNG_GetRandomNumber(&RNGHandle) >> 2);
return mp_obj_new_int(rng_get() >> 2);
}
MP_DEFINE_CONST_FUN_OBJ_0(pyb_rng_get_obj, pyb_rng_get);
#endif // MICROPY_HW_ENABLE_RNG

3
ports/stm32/rng.h
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@ -26,7 +26,8 @@
#ifndef MICROPY_INCLUDED_STMHAL_RNG_H
#define MICROPY_INCLUDED_STMHAL_RNG_H
void rng_init0(void);
#include "py/obj.h"
uint32_t rng_get(void);
MP_DECLARE_CONST_FUN_OBJ_0(pyb_rng_get_obj);