// See LICENSE for license details.

#include <stdio.h>

#include "shared.h"
#include "plic.h"
#include <string.h>

void reset_demo (void);

// Structures for registering different interrupt handlers
// for different parts of the application.
typedef void (*function_ptr_t) (void);

void no_interrupt_handler (void) {};

function_ptr_t g_ext_interrupt_handlers[9];

function_ptr_t g_m_timer_interrupt_handler = no_interrupt_handler;

// Instance data for the PLIC.

plic_instance_t g_plic;

// Simple variables for LEDs, buttons, etc.
volatile unsigned int* g_outputs  = (unsigned int *) (GPIO_BASE_ADDR + GPIO_OUT_OFFSET);
volatile unsigned int* g_inputs   = (unsigned int *) (GPIO_BASE_ADDR + GPIO_IN_OFFSET);
volatile unsigned int* g_tristates = (unsigned int *) (GPIO_BASE_ADDR + GPIO_TRI_OFFSET);


/*Entry Point for PLIC Interrupt Handler*/
void handle_m_ext_interrupt(){
  plic_source int_num  = PLIC_claim_interrupt(&g_plic);
  if ((int_num >=1 ) && (int_num <= 8)) {
    g_ext_interrupt_handlers[int_num]();
  }
  else {
    _exit(1 + (uintptr_t) int_num);
  }
  PLIC_complete_interrupt(&g_plic, int_num);
}


/*Entry Point for Machine Timer Interrupt Handler*/
void handle_m_time_interrupt(){

  clear_csr(mie, MIP_MTIP);
  
  // Reset the timer for 3s in the future.
  // This also clears the existing timer interrupt.
  
  volatile uint64_t * mtime       = (uint64_t*) MTIME_ADDR;
  volatile uint64_t * mtimecmp    = (uint64_t*) MTIMECMP_BASE_ADDR;
  uint64_t now = *mtime;
  uint64_t then = now + 3 * CLOCK_FREQUENCY / RTC_PRESCALER;
  *mtimecmp = then;
 
  // read the current value of the LEDS and invert them.
  uint32_t leds = *g_outputs;
		   
  *g_outputs = (~leds) & ((0xF << RED_LEDS_OFFSET)   |
			  (0xF << GREEN_LEDS_OFFSET) |
			  (0xF << BLUE_LEDS_OFFSET));
  

  // Re-enable the timer interrupt.
  set_csr(mie, MIP_MTIP);
 
}


/*Entry Point for Machine Timer Interrupt  Handler*/
void handle_m_timer_interrupt(){
  g_m_timer_interrupt_handler();
}

const char * instructions_msg = " \
\n\
                SIFIVE, INC.\n\
\n\
         5555555555555555555555555\n\
        5555                   5555\n\
       5555                     5555\n\
      5555                       5555\n\
     5555       5555555555555555555555\n\
    5555       555555555555555555555555\n\
   5555                             5555\n\
  5555                               5555\n\
 5555                                 5555\n\
5555555555555555555555555555          55555\n\
 55555           555555555           55555\n\
   55555           55555           55555\n\
     55555           5           55555\n\
       55555                   55555\n\
         55555               55555\n\
           55555           55555\n\
             55555       55555\n\
               55555   55555\n\
                 555555555\n\
                   55555\n\
                     5\n\
\n\
 SiFive E-Series Coreplex Demo on Arty Board\n \
 \n\
 ";

void print_instructions() {
  
  write (STDOUT_FILENO, instructions_msg, strlen(instructions_msg));
  
}

void button_0_handler(void) {

  // Rainbow LEDs!
  * g_outputs = (0x9 << RED_LEDS_OFFSET) | (0xA << GREEN_LEDS_OFFSET) | (0xC << BLUE_LEDS_OFFSET);

};


void reset_demo (){

    // Disable the machine & timer interrupts until setup is done.
  
    clear_csr(mie, MIP_MEIP);
    clear_csr(mie, MIP_MTIP);
  
    g_ext_interrupt_handlers[INT_DEVICE_BUTTON_0] = button_0_handler;
    g_ext_interrupt_handlers[INT_DEVICE_BUTTON_1] = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_BUTTON_2] = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_BUTTON_3] = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_JA_7]     = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_JA_8]     = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_JA_9]     = no_interrupt_handler;
    g_ext_interrupt_handlers[INT_DEVICE_JA_10]    = no_interrupt_handler;
    
    print_instructions();

    PLIC_enable_interrupt (&g_plic, INT_DEVICE_BUTTON_0);
       
    // Set the machine timer to go off in 3 seconds.
    // The
    volatile uint64_t * mtime       = (uint64_t*) MTIME_ADDR;
    volatile uint64_t * mtimecmp    = (uint64_t*) MTIMECMP_BASE_ADDR;
    uint64_t now = *mtime;
    uint64_t then = now + 3*CLOCK_FREQUENCY / RTC_PRESCALER;
    *mtimecmp = then;

    // Enable the Machine-External bit in MIE
    set_csr(mie, MIP_MEIP);

    // Enable the Machine-Timer bit in MIE
    set_csr(mie, MIP_MTIP);
    
    // Enable interrupts in general.
    set_csr(mstatus, MSTATUS_MIE);

}

int main(int argc, char **argv)
{
  // Set up the GPIOs such that the inputs' tristate are set.
  // The boot ROM actually does this, but still good.
  
  * g_tristates = (0xF << BUTTONS_OFFSET) | (0xF << SWITCHES_OFFSET) | (0xF << JA_IN_OFFSET);
  
  * g_outputs = (0xF << RED_LEDS_OFFSET);


  /**************************************************************************
   * Set up the PLIC
   * 
   *************************************************************************/
  PLIC_init(&g_plic, PLIC_BASE_ADDR, PLIC_NUM_SOURCES, PLIC_NUM_PRIORITIES);

  reset_demo();

  while (1);

  return 0;

}