// File    	   : dbuffer.h
// Coded by    : Scotte
// History     : Created 14/03/00 19:58:37
//
// Description : Creating and updating a double buffer
// Notes       : None


#include "profile.h"
#include "yaroze.h"
#include "dbuffer.h"
#include "gtypes.h"
#include "console.h"


// The double buffer

static sDBUFFER db[2];

// Current buffer ID

static u_word id;


// Function    : DBUFFER_Set()
// Coded by    : Scotte
// History     : Created 12/03/00 16:44:46
//
// Description : Set up the double buffer
//
// Parameters  : r - screen area
//				 x,y - display position
//
// Returns     : Double buffer input
//
// Notes       : None


void DBUFFER_Set(const RECT *r,const u_hword x,const u_hword y)
{
	// Initialise the graphics

	GsInitGraph(r->w,r->h,GPU_OFFSET,1,VRAM_MODE_16BIT);
	GsDefDispBuff(r->x,r->y+r->h,r->x,r->y);

	// Set display and drawing environments for buffer 0 and 1
		
	SetDefDrawEnv(&db[0].drawenv,r->x,r->y+r->h,r->w,r->h);
	SetDefDrawEnv(&db[1].drawenv,r->x,r->y,r->w,r->h);

	SetDefDispEnv(&db[0].dispenv,r->x,r->y,r->w,r->h);
	SetDefDispEnv(&db[1].dispenv,r->x,r->y+r->h,r->w,r->h);

	// Automatically clear background
	
	db[0].drawenv.isbg=db[1].drawenv.isbg=1;
	
	// Enable dithering

	db[0].drawenv.dtd=db[1].drawenv.dtd=1;

	// Set screen position and size

	db[0].dispenv.screen.x=db[1].dispenv.screen.x=x;
	db[0].dispenv.screen.y=db[1].dispenv.screen.y=y;
   	db[0].dispenv.screen.h=db[1].dispenv.screen.h=r->h;

	// Set the current buffer ID

	id=0;

	// Initialise the profiler

	mPROFILE_INIT(r->w,r->h,2);

	// Turn on the display

	SetDispMask(1);
}


// Function    : DBUFFER_SetOT()
// Coded by    : Scotte
// History     : Created 14/03/00 20:15:01
//
// Description : Link an ordering table to the double buffer
//
// Parameters  : ot - ordering table
//
// Returns     : None
//
// Notes       : None


void DBUFFER_SetOT(GsOT *ot)
{
	db[0].ot=ot;
	db[1].ot=ot+1;

	// Clear the OT

	GsClearOt(0,0,db[0].ot);
	GsClearOt(0,0,db[1].ot);
}


// Function    : DBUFFER_SetPB()
// Coded by    : Scotte
// History     : Created 14/03/00 20:19:57
//
// Description : Set the packet buffer
//
// Parameters  : pb - base packet buffer
//				 size - packet buffer size
//
// Returns     : None
//
// Notes       : None


void DBUFFER_SetPB(PACKET *pb,const u_word size)
{
	db[0].pb=pb;
	db[1].pb=(PACKET *)((u_byte *)pb+size);

	// Point to the current packet buffer (used by GsSort...() functions)

	GsOUT_PACKET_P=db[0].pb;

	mMESSAGE("Packet buffer size : %d (bytes)\n",size);
}

 
// Function    : DBUFFER_SetBG()
// Coded by    : Scotte
// History     : Created 14/03/00 20:07:47
//
// Description : Set the background colour
//
// Parameters  : r,g,b - new background colour
//
// Returns     : Double buffer pointer
//
// Notes       : None


void DBUFFER_SetBG(const u_byte r,const u_byte g,const u_byte b)
{
	setRGB0(&db[0].drawenv,r,g,b);
	setRGB0(&db[1].drawenv,r,g,b);
}


// Function    : DBUFFER_Swap()
// Coded by    : Scotte
// History     : Created 14/03/00 20:50:36
//
// Description : Swap display/drawing environments and starts drawing
//
// Parameters  : None
//
// Returns     : Frame time in scanlines (horizontal blanks)
//
// Notes       : None


u_word DBUFFER_Swap(void)
{
	u_word vsync;

	// Time taken during this frame

	mPROFILE_READ(0x80,0x80,0x80);

	// Wait for drawing of previous frame to finish

	while(DrawSync(1));

	// Draw the profile bars

	mPROFILE_DRAW(db[id].ot);

	// Lock to 50/60 frames per second

	vsync=VSync(0);

	// Start of a frame

	mPROFILE_START();

	// Switch ID

	id^=1;

	// Switch display and drawing environments
		
	PutDrawEnv(&db[id].drawenv);
	PutDispEnv(&db[id].dispenv);	

	// Start drawing next frame

	GsDrawOt(db[id^1].ot);

	// Swap packet buffers

	GsOUT_PACKET_P=db[id].pb;

	// Clear OT

	GsClearOt(0,0,db[id].ot);

	return(vsync);
}


// Function    : DBUFFER_CurrentOT()
// Coded by    : Scotte
// History     : Created 14/03/00 20:53:11
//
// Description : Pointer to current ordering table
//
// Parameters  : None
//
// Returns     : Current OT
//
// Notes       : None


GsOT *DBUFFER_CurrentOT(void)
{
	return(db[id].ot);
}