/******************************************************************************
 PeT mess@utanet.at 2000
******************************************************************************/
#include "driver.h"
#include "cpu/cdp1802/cdp1802.h"

#include "includes/studio2.h"

/*
  emulation of the rcata10171v1 (cdp1861) video controller
 */


static struct {
	UINT8 data[128][8];
	void *timer;
	int line;
	int dma_activ;
	int state;
	int count;
} studio2_video={ { {0} } };

int studio2_get_vsync(void)
{
	return !studio2_video.dma_activ;
}

#define COLUMNS 14
#define LINES 256
void studio2_video_dma(int cycles)
{
	int i;

	switch (studio2_video.state) {
	case 0: // deactivated
		break;
	case 1:
		studio2_video.count=COLUMNS-cycles;
		studio2_video.state++;
		cpunum_set_input_line(0, CDP1802_IRQ, PULSE_LINE);
		studio2_video.dma_activ=1;
		break;
	case 2:
		studio2_video.count-=cycles;
		if (studio2_video.count<0) {
			studio2_video.line=0;
			studio2_video.state=10;
			studio2_video.count+=COLUMNS;
		}
		break;
	case 10:
		studio2_video.count-=cycles;
		if (studio2_video.count<0) {
			for (i=0; i<8; i++) 
				studio2_video.data[studio2_video.line][i]=cdp1802_dma_read();
			studio2_video.count+=COLUMNS-8;
			if (++studio2_video.line>=128) {
				studio2_video.dma_activ=0;
				// turn off irq line !?
				studio2_video.count+=2*COLUMNS;
				studio2_video.state++;
			}
		}
		break;
	case 11:
		studio2_video.count-=cycles;
		if (studio2_video.count<0) {
// while dma_activ is high Register0 is corrected for doublescanning
// after is it waiting for it going high again
			studio2_video.dma_activ=1; 
			studio2_video.count+=COLUMNS;
			studio2_video.state++;
			if (++studio2_video.line>=256) studio2_video.state=1;
		}
		break;
	case 12:
		studio2_video.count-=cycles;
		if (studio2_video.count<0) {
			studio2_video.dma_activ=0; 
			studio2_video.count+=COLUMNS;
			studio2_video.state=11;
			if (++studio2_video.line>=256) studio2_video.state=1;
		}
		break;
	}
}

VIDEO_START( studio2 )
{
	studio2_video.state=1;
	return 0;
}

VIDEO_UPDATE( studio2 )
{
	int x, y, j;

	for (y=0; y<128;y++) {
		for (x=0, j=0; j<8;j++,x+=8*4)
			drawgfx(bitmap, Machine->gfx[0], studio2_video.data[y][j],0,
					0,0,x,y,
					0, TRANSPARENCY_NONE,0);
	}
}

 READ8_HANDLER( cdp1861_video_enable_r )
{
	studio2_video.state=1;
	return 0; //?
}

