bbb_cape/src/cape/fill_packet.c

#include "cape/fill_packet.h"

#include <string.h>

#include <STM32F2XX.h>

#include "cape/uart_dma.h"
#include "cape/uart_common.h"
#include "cape/cows.h"
#include "cape/encoder.h"
#include "cape/crc.h"
#include "cape/bootloader_handoff.h"

#define TIMESTAMP_TIM TIM6
#define RCC_APB1ENR_TIMESTAMP_TIMEN RCC_APB1ENR_TIM6EN

static uint8_t buffer1[DATA_STRUCT_SEND_SIZE] __attribute__((aligned(4)));
static uint8_t buffer2[DATA_STRUCT_SEND_SIZE] __attribute__((aligned(4)));

static uint32_t flash_checksum;
// These aren't really integers; they're (4-byte) variables whose addresses mark
// various locations.
extern uint8_t __etext, __data_start__, __data_end__;

static inline void do_fill_packet(struct DataStruct *packet) {
  static uint64_t timestamp = 0;
  counter_update_u64_u16(&timestamp, TIMESTAMP_TIM->CNT);
  packet->timestamp = timestamp;

  packet->flash_checksum = flash_checksum;

  packet->main.encoders[0] = encoder_read(0);
  packet->main.encoders[1] = encoder_read(1);
  packet->main.encoders[2] = encoder_read(2);
  packet->main.encoders[3] = encoder_read(3);
  packet->main.encoders[4] = encoder_read(4);
  packet->main.encoders[5] = encoder_read(5);
  packet->main.encoders[6] = encoder_read(6);
  packet->main.encoders[7] = encoder_read(7);
}

// Fills the new packet with data.
void uart_dma_callback(uint8_t *buffer) {
  struct {
    struct DataStruct packet;
    uint8_t padding[DATA_STRUCT_SEND_SIZE - sizeof(struct DataStruct) - 12];
    uint32_t checksum;
  } data __attribute__((aligned(4)));
  STATIC_ASSERT(sizeof(data) == DATA_STRUCT_SEND_SIZE - 8,
                The_size_of_the_data_is_wrong);
  struct DataStruct *packet = &data.packet;

  do_fill_packet(packet);

  uint32_t *p;
  memcpy(&p, &packet, sizeof(void *));
  data.checksum = crc_calculate(p, sizeof(*packet) / 4);

  memset(buffer, 0, 4);
  cows_stuff(&data, sizeof(data), buffer + 4);
}

void fill_packet_start(void) {
  RCC->APB1ENR |= RCC_APB1ENR_TIMESTAMP_TIMEN;
  TIMESTAMP_TIM->CR1 = TIM_CR1_UDIS;
  TIMESTAMP_TIM->EGR = TIM_EGR_UG;
  TIMESTAMP_TIM->CR1 |= TIM_CR1_CEN;

  crc_init();
  encoder_init();

  uint8_t *flash_end = &__etext + (&__data_start__ - &__data_end__) + 8;
  flash_checksum = crc_calculate((void *)MAIN_FLASH_START,
                                 (size_t)(flash_end - MAIN_FLASH_START) / 4);

  uart_common_configure(3000000);
  uart_dma_configure(DATA_STRUCT_SEND_SIZE, buffer1, buffer2);
}