//
// SQUARE WAVE CLOCK SIGNAL, WITH INTERRUPTS FOR MEMORY ACCESS
// PIN_CLK is monitored in Wokwi Logic Analyzer and resulting VCD file viewed in PulseView
//

#include <stdio.h>
#include <string.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"

#include "hardware/irq.h"   //
#include "hardware/pio.h"   //
#include "hardware/clocks.h"

#include "cpu6502.h"
#include "PIO_test.pio.h"

uint16_t cpu_addr;   // 65C02 address (program counter)
uint8_t cpu_data;    // 65C02 data
bool cpu_rw;         // 65C02 Read/Write pin state

static PIO PIO_O;       // PIO object
static uint SM;         // PIO state machine index
static uint PIO_IRQ;    // NVIC ARM CPU interrupt number


//
// INIT
//

void init() {
  stdio_init_all();
  printf("Pi Pico TEST : clock and interrupts\n\n");
  cpu6502_init();
}


//
// PIO INTERRUPT SERVICE ROUTINE
// Still not entirely sure of timing requirements
// Timing diags indicate address OK as PHI2 goes low
//

void pio_irq_handler() {
  gpio_put(_NMI_PIN, 1);  // SET TEST PIN FOR ANALYSER
  gpio_put(_NMI_PIN, 0);  // Just using NMI since it's not in use

  if (gpio_get(_CLOCK_PIN) == 0)   // Low, get address
    cpu6502_get_address();
  else
    cpu6502_get_data();            // else get data from bus

  pio_interrupt_clear(PIO_O, 0);
}


void test_IRQ_PIO() {
  PIO_O = pio0;
  PIO_IRQ = PIO0_IRQ_0;

  uint offset = pio_add_program(PIO_O, &pioIRQ_program);

  // TODO
  float SM_CLK_FREQ = 1000000;

  // Find a free state machine on our chosen PIO
  SM = pio_claim_unused_sm(PIO_O, true);
  pioIRQ_program_init(PIO_O, SM, offset, _CLOCK_PIN, SM_CLK_FREQ);
  pio_set_irq0_source_enabled(PIO_O, pis_interrupt0, true); // sets IRQ0
  irq_set_exclusive_handler(PIO_IRQ, pio_irq_handler);  //Set the handler in the NVIC
  irq_set_enabled(PIO_IRQ, true);                    // Enabling the PIO
}


//
// MAIN
//

int main() {
  init();

  test_IRQ_PIO();
  printf("PIO: %d, SM: %d, PIO_IRQ_num: %d \n", pio_get_index(PIO_O), SM, PIO_IRQ);

  while (true) {
    printf("."); // Show something happening
    sleep_ms(200);
  }
}