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#include "bios_funs.h"

#include "avr_cfg.h"

#include <inttypes.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include <avr/wdt.h>

#include <avr/pgmspace.h>

#ifdef BIOS_UART

#include <stdio.h>

#endif

#include <string.h>

#include <util/crc16.h>

#include "flash.h"

#include "vectors.h" // Must be included after sfr_defs.h but before any ISR()

#include "mcp2515/mcp2515.h"

//---------------------------------------------------------------------------

// Globals

volatile uint32_t gMilliSecTick;

volatile uint8_t bios_msg_full;

Can_Message_t* bios_msg_ptr; // only a pointer to main-local structure to save .bss space

//---------------------------------------------------------------------------

// Function definitions for the exported interface

void reset(void) {

    // Just loop and let the watchdog reset

    cli();

    while(1);

}

#ifdef BIOS_UART

void bios_putchar(char c) {

    UART_PUTCHAR(c);

}

char bios_getchar(void) {

    char c;

    UART_GETCHAR(c)

    return c;

}

#endif

unsigned long timebase_get(void) {

    uint8_t sreg;

    unsigned long res;

    // Disable interrupts while reading tick count

    sreg=SREG;

    cli();

    res = gMilliSecTick;

    SREG=sreg;

    return res;

}

// TODO: Insert can driver's Can_Send directly in bios interface.

Can_Return_t can_send(Can_Message_t* msg) {

    return Can_Send(msg);

}

//---------------------------------------------------------------------------

// Function definitions for the private functions

#ifdef BIOS_UART

static int console_getchar(FILE *stream) {

    return bios_getchar();

}

static int console_putchar(char c, FILE *stream) {

    bios_putchar(c);

    return 0;

}

static FILE bios_stdio = FDEV_SETUP_STREAM(console_putchar, console_getchar,

                                         _FDEV_SETUP_RW);

#endif

//---------------------------------------------------------------------------

// Interrupt Service Routines

// Read app_vectors.h!

ISR(TIMEBASE_VECTOR) {

    TIMEBASE_COUNTER -= TIMEBASE_RELOAD;

    gMilliSecTick++;

    wdt_reset();

}

void Can_Process(Can_Message_t* msg) {

    if (!(msg->ExtendedFlag)) return; // We don't care about standard CAN frames.

    if ((msg->Id & CAN_MASK_CLASS)>>CAN_SHIFT_CLASS == CAN_NMT) {

        if ((msg->Id & CAN_MASK_NMT_TYPE)>>CAN_SHIFT_NMT_TYPE == CAN_NMT_TIME) {

            // Reset watchdog as long as time messages from the master node

            // are received periodically. If anything hangs the CAN communication

            // or the master node is not up, the node will be reset.

            wdt_reset();

            //TODO: Don't care about time right now... Figure out what to do with it. 

        }

        if ((msg->Id & CAN_MASK_NMT_RID)>>CAN_SHIFT_NMT_RID == NODE_ID) {

            if ((msg->Id & CAN_MASK_NMT_TYPE)>>CAN_SHIFT_NMT_TYPE == CAN_NMT_RESET) {

                reset();

            }

            // Copy message to bios buffer if bios is done with the previous message.

            // This is also a check to see if bios is still running. When app is

            // started, bios_msg_full is never reset to 0 so the check fails and all

            // NMT communication except reset is ignored. 

            if (!(bios_msg_full)) {

                memcpy(bios_msg_ptr, msg, sizeof(Can_Message_t));

                bios_msg_full = 1;

            }

        }      

    } else if (bios->can_callback) {

        //printf("Calling app callback.\n");

        bios->can_callback(msg);

    }

}

#define BIOS_APP    1

#define BIOS_NOAPP  2

#define BIOS_PGM    3

int main() {

    void (*app_reset)(void) = 0; // Function pointer to jump to application reset vector.

    uint8_t bios_state;

    uint8_t nmt_type;

    uint8_t pagebuf[SPM_PAGESIZE];

    // These unneccessary initializations uses 12 bytes flash, just to make the compiler happy!

    uint16_t base_addr = 0;

    uint16_t offset = 0;

    uint16_t addr = 0;

    uint8_t len;

    uint16_t data;

    uint8_t send_msg = 0;

    Can_Message_t tx_msg;

    Can_Message_t bios_msg;

    bios_msg_ptr = &bios_msg;

#ifdef BIOS_UART

    // Setup USART for debug channel

    UART_INIT();

    stdout = &bios_stdio;

    stdin = &bios_stdio;

#endif

    // Initialize a suitable hardware timer to create a 1KHz interrupt.

    //TODO: Any point in having timebase in bios after wdt_reset() is moved to Can_Process?

    TIMEBASE_INIT();

    // Enable watchdog timer to protect against an application locking the

    // node by leaving interrupts disabled. 

    wdt_enable(WDTO_2S);

    // Move interrupt vectors to start of bootloader section and enable interrupts

    IVSEL_REG = _BV(IVCE);

    IVSEL_REG = _BV(IVSEL);

    sei();

    if (Can_Init() != CAN_OK) reset();

    tx_msg.RemoteFlag = 0;

    tx_msg.ExtendedFlag = 1;

    tx_msg.Id = CAN_ID_NMT_BIOS_START;

    tx_msg.DataLength = 3;

    tx_msg.Data.words[0] = BIOS_VERSION;

#ifdef BIOS_UART

    printf("BIOS start\n");

#endif

    if (pgm_read_word(0) == 0xffff) {

        // No application in flash

        // Send CAN_NMT_BIOS_START(BIOS_VERSION, 0)

        tx_msg.Data.bytes[2] = 0;

        bios_state = BIOS_NOAPP;

    } else {

        // Application exists

        // Send CAN_NMT_BIOS_START(BIOS_VERSION, 1)

        tx_msg.Data.bytes[2] = 1;

        bios_state = BIOS_APP;

    }

    while (Can_Send(&tx_msg) != CAN_OK);

    tx_msg.DataLength = 2; // All msg sent after BIOS_START are length 2 so set it once.

    // Main loop

    while (1) {

        // Wait for message

        while (!bios_msg_full);

        nmt_type = (bios_msg.Id & CAN_MASK_NMT_TYPE)>>CAN_SHIFT_NMT_TYPE;

        switch (bios_state) {

        case BIOS_APP:

            if (nmt_type == CAN_NMT_START_APP) {

                app_reset(); // Will never return

            }

            // Fall through

        case BIOS_NOAPP:

            if (nmt_type == CAN_NMT_PGM_START) {

                // Set base address

                base_addr = bios_msg.Data.words[0];

                flash_init(pagebuf);

                //send CAN_NMT_PGM_ACK(offset)

                tx_msg.Id = CAN_ID_NMT_PGM_ACK;

                tx_msg.Data.words[0] = base_addr;

                send_msg = 1;

                bios_state = BIOS_PGM;

            }

            if (nmt_type == CAN_NMT_PGM_COPY) {

                // For BIOS updating over CAN. Upload bios to application area,

                // send this message with correct parameters to copy data from

                // application to bios area and pray it will come alive again.

                flash_copy_data(bios_msg.Data.words[0],

                                bios_msg.Data.words[1],

                                bios_msg.Data.words[2]);

                // flash_copy_data will never return.

            }

            break;

        case BIOS_PGM:

            // Default to send CAN_NMT_PGM_ACK(offset)

            tx_msg.Id = CAN_ID_NMT_PGM_ACK;

            if (nmt_type == CAN_NMT_PGM_DATA) {

                // Set address = base address + offset.

                offset = bios_msg.Data.words[0];

                addr = base_addr + offset;

                // One of ACK and NACK will be sent, both have offset as data.

                tx_msg.Data.words[0] = offset;

                send_msg = 1;

                // Flash all data sent, beginning at addr.

                len = (bios_msg.DataLength+1)/2; // Number of words in message, rounded up.

                uint8_t i;

                for (i=1; i<len; i++) { // Skip first word (offset).

                    // Abort if trying to write in BIOS area.

                    if (addr >= (uint16_t)&__bios_start) {

                        // Send CAN_NMT_PGM_NACK(offset).

                        tx_msg.Id = CAN_ID_NMT_PGM_NACK;

                        break; //for loop

                    }

                    data = bios_msg.Data.words[i];

                    flash_write_word(addr, data);

                    addr += 2;

                }

                // Adjust addr if an odd number of bytes were sent, for use in crc calc.

                addr -= bios_msg.DataLength & 1;

            }

            if (nmt_type == CAN_NMT_PGM_END) {

                // Make sure a partly filled page will be flashed.

                flash_flush_buffer();

                // Calculate crc on written data.

                //TODO: This will not work if data is not sent sequentially without

                // holes, starting with offset=0. We might want to send a NACK if the

                // offset in a CAN_NMT_PGM_DATA msg differs from the expected offset.

                uint16_t loc, crc = 0;

                for (loc = base_addr; loc < addr; loc++) { // addr will be last location written + 2.

                    crc = _crc16_update(crc, pgm_read_byte(loc));

                }

                tx_msg.Data.words[0] = crc;

                send_msg = 1;

                bios_state = BIOS_NOAPP;

            }

        }

        if (send_msg) {

            while (Can_Send(&tx_msg) != CAN_OK);

            send_msg = 0;

        }

        bios_msg_full = 0; // We're done with this message, ready for the next.

    }

    return 0;

}