/***************************************************************************

  trs80.c

  Functions to emulate the video hardware of the TRS80.

***************************************************************************/
#include "includes/trs80.h"

#define FW  TRS80_FONT_W
#define FH  TRS80_FONT_H

/***************************************************************************
  Statics for this module
***************************************************************************/
static tilemap *dblwidth_tilemap;
static tilemap *normwidth_tilemap;
static tilemap *current_tilemap;
static const UINT8 *translate;
static int color;

/***************************************************************************
  Tilemap callbacks
***************************************************************************/

static TILE_GET_INFO(dblwidth_gettileinfo)
{
	SET_TILE_INFO(
		1,									/* gfx */
		translate[videoram[tile_index]],	/* character */
		color,								/* color */
		0);									/* flags */
}

static TILE_GET_INFO(normwidth_gettileinfo)
{
	SET_TILE_INFO(
		0,									/* gfx */
		translate[videoram[tile_index]],	/* character */
		color,								/* color */
		0);									/* flags */
}

/***************************************************************************
  Start the video hardware emulation.
***************************************************************************/
VIDEO_START( trs80 )
{
	dblwidth_tilemap = tilemap_create(
		dblwidth_gettileinfo,
		tilemap_scan_rows,
		TILEMAP_TYPE_PEN,
		FW * 2, FH,
		64, videoram_size / 64);

	normwidth_tilemap = tilemap_create(
		normwidth_gettileinfo,
		tilemap_scan_rows,
		TILEMAP_TYPE_PEN,
		FW, FH,
		64, videoram_size / 64);


	color = -1;
	current_tilemap = NULL;
}

/***************************************************************************
  Draw the game screen in the given mame_bitmap.
  Do NOT call osd_update_display() from this function,
  it will be called by the main emulation engine.
***************************************************************************/
VIDEO_UPDATE( trs80 )
{
	tilemap *new_tilemap;

	/* Special translation if video RAM with only 7 bits is present
	 * I don't know if it's entirely correct, but it's close ;-)
	 */
	static UINT8 translate_videoram[2][256] = {
		{
			0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,
			0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,
			0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f,
			0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f,
			0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f,
			0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f,
			0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x6b,0x6c,0x6d,0x6e,0x6f,
			0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x7b,0x7c,0x7d,0x7e,0x7f,
			0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f,
			0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f,
			0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf,
			0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf,
			0xc0,0xc1,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xcb,0xcc,0xcd,0xce,0xcf,
			0xd0,0xd1,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xdb,0xdc,0xdd,0xde,0xdf,
			0xe0,0xe1,0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xeb,0xec,0xed,0xee,0xef,
			0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
		},
		{
			0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f,
			0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f,
			0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f,
			0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f,
			0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f,
			0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f,
			0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f,
			0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f,
			0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f,
			0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f,
			0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf,
			0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf,
			0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f,
			0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f,
			0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf,
			0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf}
	};

	translate = translate_videoram[(input_port_0_r(0) & 0x40) ? 1 : 0];

	if (readinputport(0) & 0x08)
        cpunum_set_input_line(0, INPUT_LINE_NMI, PULSE_LINE);

    /* check for changed color settings */
	if (color != (readinputport(0) & 3))
    {
		color = readinputport(0) & 3;
		current_tilemap = NULL;
    }

	/* have we changed the tilemap? */
	new_tilemap = (trs80_port_ff & 0x08) ? dblwidth_tilemap : normwidth_tilemap;
	if (current_tilemap != new_tilemap)
	{
		current_tilemap = new_tilemap;
		tilemap_mark_all_tiles_dirty(current_tilemap);
	}

	tilemap_draw(bitmap, NULL, current_tilemap, 0, 0);
	return 0;
}

/***************************************************************************
  Write to video ram
***************************************************************************/

WRITE8_HANDLER( trs80_videoram_w )
{
	if (videoram[offset] != data)
	{
		videoram[offset] = data;
		if (current_tilemap)
			tilemap_mark_tile_dirty(current_tilemap, offset);
	}
}