/* 
 * File:   uart.tpp
 * Author: naopross
 *
 * Created on May 2, 2018, 7:05 PM
 * 
 * Note: Templated functions inside a namespace cannot be created outside of a 
 *       namespace because of a g++ bug in version 4.8.0 on which xc++ is based.
 *       See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56480
 */

#ifndef UART_TPP
#define UART_TPP

#include "hwconfig.hpp"
#include "uart.hpp"

extern "C" {
// #include <proc/p32mx470f512h.h>
#include <xc.h>
#include <sys/attribs.h>
}


/* templated functions */
namespace uart
{
    // access buffers
    template<unsigned dev>
    inline std::queue<uint8_t>& rx_buffer()
    {
        static_assert(dev != 0 && dev <= devices_count, "invalid device number");
        return uart::_rx_buffer[dev -1];
    }

    template<unsigned dev>
    inline std::queue<uint8_t>& tx_buffer()
    {
        static_assert(dev != 0 && dev <= devices_count, "invalid device number");
        return uart::_tx_buffer[dev -1];
    }

    template<unsigned dev>
    inline bool echo(bool enabled)
    {
        static_assert(dev != 0 && dev <= devices_count, "invalid device number");
        _echo[dev -1] = enabled;
    }

    template<unsigned dev>
    inline bool echo_enabled()
    {
        static_assert(dev != 0 && dev <= devices_count, "invalid device number");
        return _echo[dev -1];
    }

    // read from serial device
    template<unsigned dev>
    uint8_t read()
    {
        uint8_t byte = rx_buffer<dev>().front();
        rx_buffer<dev>().pop();

        return byte;
    }

    template<unsigned dev>
    uint8_t read_wait()
    {
        while (rx_buffer<dev>().empty());

        uint8_t byte = rx_buffer<dev>().front();
        rx_buffer<dev>().pop();

        return byte;
    }

#if 0
    template<unsigned dev>
    std::string read(const unsigned len)
    {
        std::string str = "";
        unsigned i = len;

        if (rx_buffer<dev>().size() < len) {
            i = rx_buffer<dev>().size();
        }

        while (i--) {
            str += read<dev>();
        }

        return str;
    }

    template<unsigned dev>
    std::string readline(const std::string& eol = "\n\r")
    {
        int eol_c = 0;

        std::string str = "";
        unsigned i = rx_buffer<dev>().size();

        while (i--) {
            str += read<dev>();

            // compare string endings
            // TODO: make it more efficient
            if (eol_c == eol.size()) {
                break;
            }

            if (str.back() == eol[eol_c]) {
                eol_c++;
            }
        }
    }

    template<unsigned dev>
    unsigned read(uint8_t *buffer, const unsigned numbytes)
    {
        uint8_t *bptr = buffer;
        unsigned len = numbytes;

        while (len--) {
            *(bptr++) = read<dev>();
        }
    }
#endif


    // write to serial device
    template<unsigned dev>
    void write(const uint8_t byte)
    {
        // disable send data flag
        IEC1bits.U1TXIE = 0;

        tx_buffer<dev>().push(byte);

        // enable send data flag
        IEC1bits.U1TXIE = 1;
    }

    template<unsigned dev>
    void write(const std::string &str)
    {
        // TODO: if size of str is reasonale, push to queue AND THEN send,
        //       right now on each call the interrupt is enabled and disabled
        // for (const char &c : str) {
            // write<dev>(c);
        // }

        // disable send data flag
        IEC1bits.U1TXIE = 0;

        for (int i = 0; i < str.size(); i++) {
            tx_buffer<1>().push(static_cast<uint8_t>(str[i]));
        }

        // enable send data flag
        IEC1bits.U1TXIE = 1;
    }

    template<unsigned dev>
    unsigned write(const uint8_t *buffer, const unsigned numbytes)
    {
        uint8_t *bptr = buffer;
        unsigned len = numbytes;

        while (len--) {
            write<dev>(*(bptr++));
        }
    }

    template<unsigned dev>
    void print(const std::string &str)
    {
        write<dev>(str);
        write<dev>("\n\r");
    }
}


/* specializations for UART1 */

#ifdef DEBUG
#include "pin.tpp"
io_pin<2> led_blue(&LATBbits, &TRISBbits, &PORTBbits);
io_pin<3> led_green(&LATBbits, &TRISBbits, &PORTBbits);
#endif

void __ISR(_UART_1_VECTOR, IPL1AUTO) usart_1_isr()
{
    if (IFS1bits.U1RXIF) {
        #ifdef DEBUG
        led_blue.toggle();
        #endif

        // wait for data to be available
        while (!U1STAbits.URXDA);
        uart::rx_buffer<1>().push(static_cast<uint8_t>(U1RXREG));

        // echo
        if (uart::echo_enabled<1>()) {
            // uart::write<1>(uart::rx_buffer<1>().front());
            IEC1bits.U1TXIE = 0;
            uart::tx_buffer<1>().push(uart::rx_buffer<1>().front());
            IEC1bits.U1TXIE = 1;
        }

        IFS1bits.U1RXIF = 0;

    } 
    // on each interrupt call, send one character
    else if (IFS1bits.U1TXIF) {
        #ifdef DEBUG
        led_green.toggle();
        #endif

        // disable TX interrupt flag
        IEC1bits.U1TXIE = 0;

        // write data
        U1TXREG = static_cast<decltype(U1TXREG)>(uart::tx_buffer<1>().front());
        uart::tx_buffer<1>().pop();

        // if not empty, enable tx flag
        if (!uart::tx_buffer<1>().empty()) {
            IEC1bits.U1TXIE = 1;
        }

        IFS1bits.U1TXIF = 0;

    } else {
        if (U1STAbits.OERR == 1) {
            U1STAbits.OERR = 0;
        }

        IFS1bits.U1EIF = 0;
    }
}

namespace uart
{
    template<>
    void initialize<1>()
    {
        // STSEL 1S;
        // IREN disabled;
        // PDSEL 8N;
        // RTSMD disabled;
        // RXINV disabled;
        // SIDL disabled;
        // WAKE disabled;
        // ABAUD disabled;
        // LPBACK disabled;
        // BRGH enabled;
        // UEN TX_RX;
        // ON enabled; 
        U1MODE = 0x8008;
        // UTXISEL TX_ONE_CHAR;
        // UTXINV disabled;
        // ADDR 0;
        // URXEN disabled;
        // OERR disabled;
        // ADM_EN disabled;
        // URXISEL RX_ONE_CHAR;
        // UTXBRK disabled;
        // UTXEN disabled;
        // ADDEN disabled; 
        U1STA = 0x0;
        // U1TXREG 0; 
        U1TXREG = 0x0;
        // BaudRate = 9600;
        // Frequency = 1000000 Hz;
        // BRG 25; 
        U1BRG = 0x19;

        IEC1bits.U1RXIE = 1;

        U1STAbits.UTXEN = 1;
        U1STAbits.URXEN = 1;

        // Enabling  UART
        U1MODEbits.ON = 1;

        // UERI: UART1 Error
        // Priority: 1
        // SubPriority: 0
        IPC7bits.U1IP = 1;
        IPC7bits.U1IS = 0;

        // map uart pins to port F
        hw::regunlock(); // unlock PPS
        CFGCONbits.IOLOCK = 0;

        U1RXRbits.U1RXR = 0x0004;   //RF1->UART1:U1RX;
        RPF0Rbits.RPF0R = 0x0003;   //RF0->UART1:U1TX;

        CFGCONbits.IOLOCK = 1; // lock   PPS
        hw::reglock();
    }

#if 0
    template<>
    void set_baudrate<1>(long baud)
    {
        
    }
#endif
}

#endif