// MEMVIEW v1.1
//
// James Shaughnessy    james@manc.u-net.com
// http://www.netyaroze-europe.com/~shaughnj


#include <libps.h>
#include "pad.h"


#define SCR_ADDR (0x80090000)
#define MIN_ADDR (0x80000000)
#define MAX_ADDR (0x801fffff)



#define OT_LENGTH (1)
#define NUM_SPRITES (1+1)


// Two Ordering Tables, one for each buffer
GsOT WorldOT[2];
// Two Ordering Table Tags, one for each buffer
GsOT_TAG OTTag[2][1<<OT_LENGTH];
//Also allocate memory used for depth sorting, a block for each buffer
PACKET GpuPacketArea[2][NUM_SPRITES*sizeof(GsSPRITE)];


// Global Variables
int activeBuff;
int hsyncs;
u_long padStatus;
u_long memAddr = SCR_ADDR;
int scrW, scrH, bitDepth;

// Allow 256 lines
extern DISPENV GsDISPENV;


// Function Prototypes
void UpdateScreen();
void InitGraphics();


main()
{
  // Init variables
  scrW = 320;
  scrH = 256;
  bitDepth = 16;


  PadInit();
  InitGraphics();

  while(1)
  {
    padStatus = PadRead();

    // Quit if both Select and Start pressed
    if (padStatus & PAD1select && padStatus & PAD1start) break;

    activeBuff = GsGetActiveBuff();

    // Set packet work base
    GsSetWorkBase((PACKET *)GpuPacketArea[activeBuff]);

    // Clear the Ordering Table
    GsClearOt(0, 0, &WorldOT[activeBuff]);


    // Go as far down memory as possible (given current scrW) to view stack
    if (padStatus & PAD1start)
      memAddr = MAX_ADDR;

    // Scroll address
    if (padStatus & PAD1up) memAddr -= scrW * (4 + (padStatus & PAD1R1));
    if (padStatus & PAD1down) memAddr += scrW * (4 + (padStatus & PAD1R1));
    if (padStatus & PAD1left)
      if (padStatus & PAD1L1) { scrW -= 1 + (padStatus & PAD1R1); if (scrW < 1) scrW = 1; }
      else
        memAddr -= 1 * (4 + (padStatus & PAD1R1));
    if (padStatus & PAD1right)
      if (padStatus & PAD1L1) { scrW += 1 + (padStatus & PAD1R1); if (scrW > 640) scrW = 640; }
      else
        memAddr += 1 * (4 + (padStatus & PAD1R1));

    // Limit address to avoid DMA crash
    if (memAddr < MIN_ADDR) memAddr = MIN_ADDR;
    else if (memAddr > MAX_ADDR-(scrW*scrH*bitDepth/8)) memAddr = MAX_ADDR-(scrW*scrH*bitDepth/8);


    UpdateScreen();


    // Display H-Sync counter
    FntPrint("HSyncs: %d\n", hsyncs);
    FntPrint("Memory Address = %x\n", memAddr);
    FntPrint("Screen width = %d\n", scrW);
    FntPrint("Screen height = %d\n", scrH);
    FntPrint("Bit depth = %d\n", bitDepth);
    FntFlush(-1);

    // Wait for end of drawing, a vertical blank then swap buffers
    DrawSync(0);
    hsyncs = VSync(0);
    GsSwapDispBuff();

    // Register Clear in OT
    GsSortClear(0, 0, 0, &WorldOT[activeBuff]);

    // Draw the Ordering Table
    GsDrawOt(&WorldOT[activeBuff]);
  }

  ResetGraph(0);
  return 0;
}


void UpdateScreen()
{
  RECT rect;

  u_long *ptrAddr = (u_long *)memAddr;

  if (scrW < 320)
    rect.x = (320-scrW)>>1;
  else
    rect.x = 0;
  rect.y = activeBuff<<8;
  rect.w = scrW;
  rect.h = scrH;

  LoadImage(&rect, ptrAddr);

  DrawSync(0);
}


// Initialises Video, 3D Graphics and the Frame Buffer
void InitGraphics()
{
  int i;

  // Setup graphics PAL 320x256 
  SetVideoMode(MODE_PAL);
  GsInitGraph(320, 256, 4, 0, 0);
  GsDISPENV.screen.y = 20;
  GsDISPENV.screen.h = 256;
  GsDefDispBuff(0, 0, 0, 256);

  // Init Ordering Tables
  for (i = 0; i < 2; i++) {
    WorldOT[i].length = OT_LENGTH;
    WorldOT[i].org = OTTag[i];
    GsClearOt(0, 0, &WorldOT[i]);
  }

  // Loads the debug font into Frame Buffer
  FntLoad(960, 256);
  // Font printing location
  FntOpen(16, 200, 256, 192, 0, 512);
}





// ****** PAD routines ******

// call once only in program initialisation
void PadInit (void)
{
  GetPadBuf(&bb0, &bb1);
}

// call once per VSync(0)
// puts controller pad status into unsigned long integer
// please refer to the manuals if you want explanation 
// of the internals of this function
u_long PadRead(void)
{
  return(~(*(bb0+3) | *(bb0+2) << 8 | *(bb1+3) << 16 | *(bb1+2) << 24));
}