test to send an array of uint8_t's via SPI using both polling and interrupts

spi_xfer.c

#include "project.h"
#include <string.h>

enum {
    MAX_ITEMS = 10,
};

ring_buffer_t rx_buffer;
ring_buffer_t tx_buffer;

uint8_t xfer_cnt = 0;

typedef enum {
    TX_IDLE,
    TX_TRANSFERRING
} tx_state = TX_IDLE;

void spi_xfer_asynch(const uint8_t *data, const size_t size);

CY_ISR_PROTO(SPI_rx_handler);
CY_ISR_PROTO(SPI_tx_handler);

int main(void)
{
    // test data
    const uint8_t data_spi[10] = {0x01, 0x02, 0x03, 0x04, 0x05,
                              0x06, 0x07, 0x08, 0x09, 0x0A};
    
    // SPI_rx_handler is a callback executed when we transfer 1 byte
    isr_SPI_Rx_StartEx(SPI_rx_handler);
    // SPI_tx_handler is a callback executed when we receive 1 byte
    isr_SPI_Tx_StartEx(SPI_tx_handler);
    
    // Enable interrupts
    CyGlobalIntEnable;
    
    // Configure and enable the peripherals
    SPI_Start();
    UART_Start();
    
    UART_PutChar(0x0C); // clear the screen
    UART_PutString("Test SPI with interrupts.\r\n");

    while (1) {
        if (tx_state == TX_IDLE) {
            spi_xfer_async("foobar", sizeof("foobar"));
        }
    }
}

void spi_xfer_asynch(const uint8_t *data, const size_t size)
{
    for (size_t i = 0; i < size; i++) {
        if (ring_buffer_is_full(&rx_buffer)) {
            // OVERFLOW
        } else {
            ring_buffer_add(&rx_buffer, data[i]);
        }
    }
    
    // we need to disable interrupts because we are writing to tx_state
    disable_interrupts();
    if (tx_state == TX_IDLE) {
        tx_state = TX_TRANSFERRING;
        SS_Write(0);
        // transfer 1 byte so we can trigger the SPI_tx_handler
        SPI_WriteTxData(ring_buffer_get());        
    }
    enable_interrupts();
}

CY_ISR(SPI_rx_handler)
{
    // TODO
}

CY_ISR(SPI_tx_handler)
{
    if (tx_state != TX_TRANSFERRING) {
        // WTF
    } else {
        if (!ring_buffer_is_empty(&rx_buffer)) {
            SPI_WriteTxData(ring_buffer_get(&rx_buffer));
        } else {
            tx_state = TX_IDLE;
            SS_Write(1);
        }
    }
}

/* [] END OF FILE */