//
// Test program for GBA devkitadv
//

#include "pwave.h"

// 型情報
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned long u32;
typedef signed char s8;
typedef signed short s16;
typedef signed long s32;

// 制御レジスタ情報
#define SND_ABCTRL    0x04000082
#define SND_SWITCH    0x04000084
#define SND_CHAFIFO   0x040000A0
#define SND_CHBFIFO   0x040000A4
#define DMA1_SRCAD    0x040000BC
#define DMA1_DSTAD    0x040000C0
#define DMA1_COUNT    0x040000C4
#define DMA1_CTRL     0x040000C6
#define TIMER0_COUNT  0x04000100
#define TIMER0_CTRL   0x04000102
#define TIMER1_COUNT  0x04000104
#define TIMER1_CTRL   0x04000106
#define TIMER2_COUNT  0x04000108
#define TIMER2_CTRL   0x0400010A
#define TIMER3_COUNT  0x0400010C
#define TIMER3_CTRL   0x0400010E
#define KEY_INPUT     0x04000130
#define KEY_INTERRUPT 0x04000132
#define INT_IE        0x04000200
#define INT_IF        0x04000202
#define INT_IME       0x04000208
#define register(p) *((u16*) p)
#define register4(p) *((u32*) p)

#define KEY_A      0x0001
#define KEY_B      0x0002
#define KEY_SELECT 0x0004
#define KEY_START  0x0008
#define KEY_RIGHT  0x0010
#define KEY_LEFT   0x0020
#define KEY_UP     0x0040
#define KEY_DOWN   0x0080
#define KEY_R      0x0100
#define KEY_L      0x0200
#define KEY_INTEN  0x4000
#define KEY_INTAND 0x8000

#define TIM_PRESCALAR0 0x0000 // about    60 ns
#define TIM_PRESCALAR1 0x0001 // about   380 ns
#define TIM_PRESCALAR2 0x0002 // about 15300 ns
#define TIM_PRESCALAR3 0x0003 // about 61000 ns

#define TIM_CASCADE 0x0004
#define TIM_INTEN   0x0040
#define TIM_ON      0x0080

#define INT_VBLANK 0x0001
#define INT_HBLANK 0x0002
#define INT_VCOUNT 0x0004
#define INT_TIMER0 0x0008
#define INT_TIMER1 0x0010
#define INT_TIMER2 0x0020
#define INT_TIMER3 0x0040
#define INT_COMM   0x0080
#define INT_DMA0   0x0100
#define INT_DMA1   0x0200
#define INT_DMA2   0x0400
#define INT_DMA3   0x0800
#define INT_KEY    0x1000
#define INT_GAMEP  0x2000

#define SND_ALL_ON   0x0080
#define SND_CHARESET  0x0800
#define SND_CHATIMER0 0x0000
#define SND_CHATIMER1 0x0400
#define SND_CHALEFT   0x0200
#define SND_CHARIGHT  0x0100
#define SND_CHAHALF   0x0000 
#define SND_CHAFULL   0x0004
#define SND_CHBRESET  0x8000
#define SND_CHBTIMER0 0x0000
#define SND_CHBTIMER1 0x4000
#define SND_CHBLEFT   0x2000
#define SND_CHBRIGHT  0x1000
#define SND_CHBHALF   0x0000 
#define SND_CHBFULL   0x0008

#define DMA_DISABLE   0x0000
#define DMA_ENABLE    0x8000
#define DMA_INTEN     0x4000
#define DMA_STARTIMD  0x0000
#define DMA_STARTVBL  0x1000
#define DMA_STARTHBL  0x2000
#define DMA_STARTFIFO 0x3000
#define DMA_SIZE16    0x0000
#define DMA_SIZE32    0x0400
#define DMA_ONCE      0x0000
#define DMA_REPEAT    0x0200

#define DMA_SRCINC 0x0000
#define DMA_SRCDEC 0x0080
#define DMA_SRCFIX 0x0100

#define DMA_DSTINC 0x0000
#define DMA_DSTDEC 0x0020
#define DMA_DSTFIX 0x0040
#define DMA_DSTREL 0x0060 // 増加とリロード

// マルチブート指定
int __gba_multiboot = 0;

volatile u8 playing = 0;
volatile u32 wave_count = 0;
volatile u32 wave_size = 117156;
volatile u32 wave_freq = 11000;

void StopMusic(){
  // 再生フラグをオフに
  playing = 0;
  // サウンドの設定をオフに
  register(SND_ABCTRL) = 0;
  // ＤＭＡ１ 停止
  register(DMA1_CTRL) = 0;
  // タイマー０ 停止
  register(TIMER0_CTRL) = 0;
  // カウントを 0 に
  wave_count = 0;
}

void StartMusic()
{
  int count;

  if(playing == 1){
    // 再生中なら曲を停止
    StopMusic();
  }

  // サウンドを有効に
  register(SND_SWITCH) = SND_ALL_ON;

  // チャンネルＡの設定
  register(SND_ABCTRL) = SND_CHARESET | SND_CHATIMER0 | SND_CHALEFT | SND_CHARIGHT | SND_CHAFULL;

  // ＤＭＡ転送元と先の設定
  register4(DMA1_SRCAD) = (u32)pwave;
  register4(DMA1_DSTAD) = SND_CHAFIFO;

  // タイマーの設定
  count = 16777216 / wave_freq; // 16777216 = 2^24
  register(TIMER0_COUNT) = (u16)-count;

  // ＤＭＡ転送の設定
  register(DMA1_CTRL) = DMA_ENABLE | DMA_STARTFIFO | DMA_SIZE32 | DMA_REPEAT | DMA_SRCINC | DMA_DSTFIX;

  // タイマー０を開始
  register(TIMER0_CTRL) = TIM_ON | TIM_INTEN | TIM_PRESCALAR0;

  // 再生フラグをオンに
  playing = 1;
}

void IRQ_Handler()
{
  u16 Int_Flag;

  register(INT_IME) =  0;

  Int_Flag = register(INT_IF);

  if(Int_Flag & INT_KEY){
    if((register(KEY_INPUT) & KEY_A) == 0){
      StartMusic();
    }
    if((register(KEY_INPUT) & KEY_B) == 0){
      // ＤＭＡ１ 停止
      register(DMA1_CTRL) = 0;
      // タイマー０ 停止
      register(TIMER0_CTRL) = 0;
    }
  }
  if(Int_Flag & INT_TIMER0){
    if(playing == 1){
      wave_count++;
      if(wave_count >= (wave_size - 20)){
        StopMusic();
      }

      if(playing == 0){
        StartMusic();
      }
    }
  }

  register(INT_IF) = Int_Flag;
  register(INT_IME) = 1;
}

void WaitForVsync(void)
{
  while(*(volatile u16*)0x4000006 >= 160){};
  while(*(volatile u16*)0x4000006 < 160){};
}


// メインプログラム
int main(void)
{
  // サウンドの設定
  register(SND_ABCTRL) = 0;

  // 割り込みの設定
  register(INT_IME) =  0;

  *(u32*)0x03007FFC = (u32)IRQ_Handler;

  register(KEY_INTERRUPT) = KEY_INTEN | KEY_A | KEY_B;
  register(INT_IE) |= (INT_TIMER0 | INT_KEY);

  // 割り込み開始
  register(INT_IME) =  1;

  // 無限ループ
  while(1){
    // Ｖブランクまで待機
    WaitForVsync();
  }
}