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-rw-r--r--src/cc20rng/main.c118
1 files changed, 53 insertions, 65 deletions
diff --git a/src/cc20rng/main.c b/src/cc20rng/main.c
index e478409..88b5144 100644
--- a/src/cc20rng/main.c
+++ b/src/cc20rng/main.c
@@ -31,12 +31,12 @@
*/
#include <string.h>
+#include "cc20_prng.h"
#include "main.h"
#include "stm_init.h"
-#include "cc20_prng.h"
-#define UART_RANDOM_BYTES_PER_CHUNK 8
-#define RESEED_BLOCKS CHACHA20_MAX_BLOCK_COUNTER
+#define UART_RANDOM_BYTES_PER_CHUNK 8
+#define RESEED_BLOCKS CHACHA20_MAX_BLOCK_COUNTER
extern DMA_HandleTypeDef hdma_tim;
@@ -44,19 +44,22 @@ static UART_HandleTypeDef *huart;
static __IO ITStatus UartReady = RESET;
static union {
- uint8_t rnd[257]; /* 256 bytes + 1 for use in the POST */
+ uint8_t rnd[257]; /* 256 bytes + 1 for use in the POST */
uint32_t rnd32[64];
} buf;
-/* First DMA value (DMA_counters[0]) is unreliable, leftover in DMA FIFO perhaps? */
-#define FIRST_DMA_IDX_USED 3
+/* First DMA value (DMA_counters[0]) is unreliable, leftover in DMA FIFO
+ * perhaps? */
+#define FIRST_DMA_IDX_USED 3
/*
* Number of counters used to produce 8 bits of entropy is:
- * 8 * 4 - four flanks are used to produce two (hopefully) uncorrelated bits (a and b)
+ * 8 * 4 - four flanks are used to produce two (hopefully) uncorrelated bits
+ * (a and b)
* * 2 - von Neumann will on average discard 1/2 of the bits 'a' and 'b'
*/
-#define DMA_COUNTERS_NUM ((UART_RANDOM_BYTES_PER_CHUNK * 8 * 4 * 2) + FIRST_DMA_IDX_USED + 1)
+#define DMA_COUNTERS_NUM \
+ ((UART_RANDOM_BYTES_PER_CHUNK * 8 * 4 * 2) + FIRST_DMA_IDX_USED + 1)
struct DMA_params {
volatile uint32_t buf0[DMA_COUNTERS_NUM];
volatile uint32_t buf1[DMA_COUNTERS_NUM];
@@ -64,28 +67,23 @@ struct DMA_params {
};
static struct DMA_params DMA = {
- {},
- {},
- 0,
+ {}, {}, 0,
};
-
/* The main work horse functions */
static void get_entropy32(uint32_t num_bytes, uint32_t buf_idx);
/* Various support functions */
static inline uint32_t get_one_bit(void) __attribute__((__always_inline__));
static volatile uint32_t *restart_DMA(void);
static inline volatile uint32_t *get_DMA_read_buf(void);
-static inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_t dmabuf_idx);
+static inline uint32_t safe_get_counter(volatile uint32_t *dmabuf,
+ const uint32_t dmabuf_idx);
static void check_uart_rx(UART_HandleTypeDef *this);
static void cc_reseed(struct cc20_state *cc);
void Error_Handler(void);
-
-int
-main()
-{
+int main() {
uint32_t i, timeout, block_counter = 0;
struct cc20_state cc, out;
HAL_StatusTypeDef res;
@@ -97,10 +95,10 @@ main()
DMA.buf1[i] = 0xffff0100 + i;
}
- stm_init((uint32_t *) &DMA.buf0, DMA_COUNTERS_NUM);
+ stm_init((uint32_t *)&DMA.buf0, DMA_COUNTERS_NUM);
- if (! chacha20_prng_self_test()) {
- Error_Handler();
+ if (!chacha20_prng_self_test()) {
+ Error_Handler();
}
/* Ensure there is actual Timer IC counters in both DMA buffers. */
@@ -110,29 +108,25 @@ main()
huart = &huart1;
/* Toggle GREEN LED to show we've initialized */
- {
- for (i = 0; i < 10; i++) {
- HAL_GPIO_TogglePin(LED_PORT, LED_GREEN);
- HAL_Delay(125);
- }
+ for (i = 0; i < 10; i++) {
+ HAL_GPIO_TogglePin(LED_PORT, LED_GREEN);
+ HAL_Delay(125);
}
/* Generate initial block of random data directly into buf */
cc_reseed(&cc);
block_counter = RESEED_BLOCKS;
- chacha20_prng_block(&cc, block_counter--, (struct cc20_state *) buf.rnd32);
+ chacha20_prng_block(&cc, block_counter--, (struct cc20_state *)buf.rnd32);
- /*
- * Main loop
- */
+ /* Main loop */
while (1) {
- if (! (block_counter % 1000)) {
+ if (!(block_counter % 1000)) {
HAL_GPIO_TogglePin(LED_PORT, LED_YELLOW);
}
- if (! block_counter) {
- cc_reseed(&cc);
- block_counter = RESEED_BLOCKS;
+ if (!block_counter) {
+ cc_reseed(&cc);
+ block_counter = RESEED_BLOCKS;
}
/* Send buf on UART (non blocking interrupt driven send). */
@@ -143,12 +137,14 @@ main()
chacha20_prng_block(&cc, block_counter--, &out);
/* Copying using a loop is faster than memcpy on STM32 */
for (i = 0; i < CHACHA20_NUM_WORDS; i++) {
- buf.rnd32[i] = out.i[i];
+ buf.rnd32[i] = out.i[i];
}
if (res == HAL_OK) {
timeout = 0xffff;
- while (UartReady != SET && timeout) { timeout--; }
+ while (UartReady != SET && timeout) {
+ timeout--;
+ }
}
if (UartReady != SET) {
@@ -164,22 +160,19 @@ main()
}
}
-
/**
* @brief Reseed chacha20 state with hardware generated entropy.
* @param cc: ChaCha20 state
* @retval None
*/
-static void
-cc_reseed(struct cc20_state *cc)
-{
- HAL_GPIO_WritePin(LED_PORT, LED_BLUE, GPIO_PIN_SET);
+static void cc_reseed(struct cc20_state *cc) {
+ HAL_GPIO_WritePin(LED_PORT, LED_BLUE, GPIO_PIN_SET);
- get_entropy32(CHACHA20_BLOCK_SIZE / 4, 0);
- restart_DMA();
- chacha20_prng_reseed(cc, (uint32_t *) &buf);
+ get_entropy32(CHACHA20_BLOCK_SIZE / 4, 0);
+ restart_DMA();
+ chacha20_prng_reseed(cc, (uint32_t *)&buf);
- HAL_GPIO_WritePin(LED_PORT, LED_BLUE, GPIO_PIN_RESET);
+ HAL_GPIO_WritePin(LED_PORT, LED_BLUE, GPIO_PIN_RESET);
}
/**
@@ -188,16 +181,14 @@ cc_reseed(struct cc20_state *cc)
* @param start: Start index value into buf.rnd32.
* @retval None
*/
-static inline void get_entropy32(uint32_t count, const uint32_t start)
-{
+static inline void get_entropy32(uint32_t count, const uint32_t start) {
uint32_t i, bits, buf_idx;
buf_idx = start;
do {
bits = 0;
- /* Get 32 bits of entropy.
- */
+ /* Get 32 bits of entropy. */
for (i = 32; i; i--) {
bits <<= 1;
bits += get_one_bit();
@@ -213,8 +204,7 @@ static inline void get_entropy32(uint32_t count, const uint32_t start)
* @param None
* @retval One bit, in the LSB of an uint32_t since this is a 32 bit MCU.
*/
-static inline uint32_t get_one_bit()
-{
+static inline uint32_t get_one_bit() {
register uint32_t a, b, temp;
/* Start at end of buffer so restart_DMA() is called. */
static uint32_t dmabuf_idx = DMA_COUNTERS_NUM - 1;
@@ -264,8 +254,7 @@ static inline uint32_t get_one_bit()
* @param None
* @retval Pointer to buffer currently being read from.
*/
-static inline volatile uint32_t *get_DMA_read_buf(void)
-{
+static inline volatile uint32_t *get_DMA_read_buf(void) {
return DMA.write_buf ? DMA.buf0 : DMA.buf1;
}
@@ -274,8 +263,7 @@ static inline volatile uint32_t *get_DMA_read_buf(void)
* @param None
* @retval Pointer to buffer currently being written to.
*/
-static inline volatile uint32_t *get_DMA_write_buf(void)
-{
+static inline volatile uint32_t *get_DMA_write_buf(void) {
return DMA.write_buf ? DMA.buf1 : DMA.buf0;
}
@@ -284,16 +272,17 @@ static inline volatile uint32_t *get_DMA_write_buf(void)
* @param None
* @retval Pointer to buffer full of Timer IC values ready to be consumed.
*/
-static volatile uint32_t *restart_DMA(void)
-{
+static volatile uint32_t *restart_DMA(void) {
/* Wait for transfer complete flag to become SET. Trying to change the
* M0AR register while the DMA is running is a no-no.
*/
- while(__HAL_DMA_GET_FLAG(&hdma_tim, __HAL_DMA_GET_TC_FLAG_INDEX(&hdma_tim)) == RESET) { ; }
+ while (__HAL_DMA_GET_FLAG(&hdma_tim,
+ __HAL_DMA_GET_TC_FLAG_INDEX(&hdma_tim)) == RESET)
+ ;
/* Switch buffer being written to */
DMA.write_buf ^= 1;
- hdma_tim.Instance->M0AR = (uint32_t) get_DMA_write_buf();
+ hdma_tim.Instance->M0AR = (uint32_t)get_DMA_write_buf();
/* Start at 0 to help manual inspection */
TIM2->CNT = 0;
@@ -311,7 +300,8 @@ static volatile uint32_t *restart_DMA(void)
* @param dmabuf_idx: Word index into `dmabuf'.
* @retval One Timer IC counter value.
*/
-static inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_t dmabuf_idx) {
+static inline uint32_t safe_get_counter(volatile uint32_t *dmabuf,
+ const uint32_t dmabuf_idx) {
register uint32_t a;
/* Prevent re-use of values. DMA stored values are <= 0xffff. */
do {
@@ -322,8 +312,7 @@ static inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_
}
/* UART transmit complete callback */
-void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UH)
-{
+void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UH) {
if ((UH->Instance == USART1 && huart->Instance == USART1) ||
(UH->Instance == USART2 && huart->Instance == USART2)) {
/* Signal UART transmit complete to the code in the main loop. */
@@ -350,10 +339,9 @@ static void check_uart_rx(UART_HandleTypeDef *this) {
* @param None
* @retval None
*/
-
-void Error_Handler(void)
-{
+void Error_Handler(void) {
/* Turn on RED LED and then loop indefinitely */
HAL_GPIO_WritePin(LED_PORT, LED_RED, GPIO_PIN_SET);
- while(1) { ; }
+ while (1)
+ ;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-28 09:16:58 +0000