#include <modemCom.h>
#include <main.h>
#include <usart.h>



void modemISR() {
    uint32_t isrflags   = READ_REG(modemUart.Instance->SR);
    uint32_t cr1its     = READ_REG(modemUart.Instance->CR1);

    // RXNEIE doesn't need to be considered since it is always on and more over the
    // RXNE flag is cleared by reading the DR, which is done in any case
    if (((isrflags & USART_SR_RXNE) != RESET) || ((isrflags & (USART_SR_ORE | USART_SR_FE | USART_SR_PE | USART_SR_NE)) != RESET)) {
        // Error flags are only valid together with the RX flag.
        // They will be cleared by reading SR (already done above) followed by reading DR (below).
        bool errorFound = false;
        if ((isrflags & USART_SR_ORE) != RESET) {
            mbusCommStats.uartOverrunCnt += 1;
            errorFound = true;
        }
        if ((isrflags & USART_SR_FE) != RESET) {
            mbusCommStats.uartFramingErrCnt += 1;
            errorFound = true;
        }
        if ((isrflags & USART_SR_PE) != RESET) {
            mbusCommStats.uartParityErrCnt += 1;
            errorFound = true;
        }
        if ((isrflags & USART_SR_NE) != RESET) {
            mbusCommStats.uartNoiseErrCnt += 1;
            errorFound = true;
        }
        mbusCommStats.uartOctetCnt += 1;
        // it is required to read the DR in any case here, not only when the buffer has space
        // otherwise the interrupt flag won't be reset, particularly important in case of ORE
        uint8_t data = (uint8_t)(mbusUart.Instance->DR & (uint8_t)0x00FF);
        if ((! errorFound) &&
            (mbusCommHandle.receiveBuffer.writeIdx < mbusCommHandle.receiveBuffer.size)) {
            mbusCommHandle.receiveBuffer.buffer[mbusCommHandle.receiveBuffer.writeIdx] = data;
            mbusCommHandle.receiveBuffer.writeIdx += 1;
        }
    } 
    
    // TXEIE needs to be considered since TXE is cleared by writing the DR, which isn't done
    // after the last octet sent
    if (((isrflags & USART_SR_TXE) != RESET) && ((cr1its & USART_CR1_TXEIE) != RESET)) {
        if (mbusCommHandle.sendBuffer.readIdx < mbusCommHandle.sendBuffer.writeIdx) {
            mbusUart.Instance->DR = mbusCommHandle.sendBuffer.buffer[mbusCommHandle.sendBuffer.readIdx];
            mbusCommHandle.sendBuffer.readIdx += 1;
            if (mbusCommHandle.sendBuffer.readIdx == mbusCommHandle.sendBuffer.writeIdx) {
                __HAL_UART_DISABLE_IT(&mbusUart, UART_IT_TXE);
                __HAL_UART_ENABLE_IT(&mbusUart, UART_IT_TC);
            }
        }
    } 

    // advance the state for the engine only when the last octet is shifted out completely
    if (((isrflags & USART_SR_TC) != RESET) && ((cr1its & USART_CR1_TCIE) != RESET)) {
        __HAL_UART_DISABLE_IT(&mbusUart, UART_IT_TC);
        mbusCommHandle.state = MBCS_SENDING_DONE;
    }
}