#include <stdint.h>
#include <stdbool.h>
#include "driverlib/pwm.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/timer.h"
#include "driverlib/pin_map.h"
#include "inc/tm4c1294ncpdt.h"
#include "driverlib/interrupt.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/fpu.h"
#include <math.h>
#include "driverlib/pwm.h"
#include <stdlib.h>
#include "audio_waveform.h"
#include "frequency.h"

#define AUDIO_PWM_PERIOD 258

uint32_t gSamplingRateDivider = 29; // sampling rate divider

void configure_audio() {
  // configure M0PWM2, at GPIO PF2, BoosterPack 1 header C1 pin 2
  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOG);
  GPIOPinTypePWM(GPIO_PORTG_BASE, GPIO_PIN_1);
  GPIOPinConfigure(GPIO_PG1_M0PWM5);
  GPIOPadConfigSet(GPIO_PORTG_BASE, GPIO_PIN_1, GPIO_STRENGTH_2MA,
                   GPIO_PIN_TYPE_STD);
  // configure the PWM0 peripheral, gen 2, outputs 5
  SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
  // use system clock without division
  PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_1);
  PWMGenConfigure(PWM0_BASE, PWM_GEN_2,
                  PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC);

  PWMGenPeriodSet(PWM0_BASE, PWM_GEN_2,
                  AUDIO_PWM_PERIOD);
  PWMPulseWidthSet(PWM0_BASE, PWM_OUT_5,
                   roundf((float)AUDIO_PWM_PERIOD * 0.5f));

  gSamplingRateDivider =  gSystemClock / AUDIO_PWM_PERIOD / AUDIO_SAMPLING_RATE;

  PWMGenIntTrigEnable(PWM0_BASE, PWM_GEN_2, PWM_INT_CNT_ZERO);

  PWMOutputState(PWM0_BASE, PWM_OUT_5_BIT, true);
  PWMGenEnable(PWM0_BASE, PWM_GEN_2);
}

uint32_t gPWMSample = 0; // PWM sample counter
void PWM_ISR(void)
{
    PWMGenIntClear(PWM0_BASE, PWM_GEN_2, PWM_INT_CNT_ZERO); // clear PWM interrupt flag
    // waveform sample index
    int i = (gPWMSample++) / gSamplingRateDivider;
    // write directly to the PWM compare B register
    PWM0_2_CMPB_R = 1 + gWaveform[i];
    if (i > gWaveformSize) { // if at the end of the waveform array
        // disable these interrupts
        PWMIntDisable(PWM0_BASE, PWM_INT_GEN_2);
        // reset sample index so the waveform starts from the beginning
        gPWMSample = 0;
    }
}