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AmigActive 10
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vidhrdw
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brkthru.c
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C/C++ Source or Header
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2000-05-04
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8KB
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310 lines
/***************************************************************************
breakthru:vidhrdw.c
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
unsigned char *brkthru_scroll;
unsigned char *brkthru_videoram;
size_t brkthru_videoram_size;
static int bgscroll;
static int bgbasecolor;
static int flipscreen;
/***************************************************************************
Convert the color PROMs into a more useable format.
Break Thru has one 256x8 and one 256x4 palette PROMs.
I don't know for sure how the palette PROMs are connected to the RGB
output, but it's probably the usual:
bit 7 -- 220 ohm resistor -- GREEN
-- 470 ohm resistor -- GREEN
-- 1 kohm resistor -- GREEN
-- 2.2kohm resistor -- GREEN
-- 220 ohm resistor -- RED
-- 470 ohm resistor -- RED
-- 1 kohm resistor -- RED
bit 0 -- 2.2kohm resistor -- RED
bit 3 -- 220 ohm resistor -- BLUE
-- 470 ohm resistor -- BLUE
-- 1 kohm resistor -- BLUE
bit 0 -- 2.2kohm resistor -- BLUE
***************************************************************************/
void brkthru_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
int i;
#define TOTAL_COLORS(gfxn) (Machine->gfx[gfxn]->total_colors * Machine->gfx[gfxn]->color_granularity)
#define COLOR(gfxn,offs) (colortable[Machine->drv->gfxdecodeinfo[gfxn].color_codes_start + offs])
for (i = 0;i < Machine->drv->total_colors;i++)
{
int bit0,bit1,bit2,bit3;
bit0 = (color_prom[0] >> 0) & 0x01;
bit1 = (color_prom[0] >> 1) & 0x01;
bit2 = (color_prom[0] >> 2) & 0x01;
bit3 = (color_prom[0] >> 3) & 0x01;
*(palette++) = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;
bit0 = (color_prom[0] >> 4) & 0x01;
bit1 = (color_prom[0] >> 5) & 0x01;
bit2 = (color_prom[0] >> 6) & 0x01;
bit3 = (color_prom[0] >> 7) & 0x01;
*(palette++) = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;
bit0 = (color_prom[Machine->drv->total_colors] >> 0) & 0x01;
bit1 = (color_prom[Machine->drv->total_colors] >> 1) & 0x01;
bit2 = (color_prom[Machine->drv->total_colors] >> 2) & 0x01;
bit3 = (color_prom[Machine->drv->total_colors] >> 3) & 0x01;
*(palette++) = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;
color_prom++;
}
/* characters use colors 0-7 */
for (i = 0;i < TOTAL_COLORS(0);i++)
COLOR(0,i) = i;
/* background tiles use colors 128-255 */
for (i = 0;i < TOTAL_COLORS(1);i++)
COLOR(1,i) = i + 128;
/* sprites use colors 64-127 */
for (i = 0;i < TOTAL_COLORS(9);i++)
COLOR(9,i) = i + 64;
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
int brkthru_vh_start(void)
{
if ((dirtybuffer = malloc(videoram_size)) == 0)
{
generic_vh_stop();
return 1;
}
memset(dirtybuffer,1,videoram_size);
/* the background area is twice as wide as the screen */
if ((tmpbitmap = osd_create_bitmap(2*Machine->drv->screen_width,Machine->drv->screen_height)) == 0)
{
free(dirtybuffer);
return 1;
}
return 0;
}
/***************************************************************************
Stop the video hardware emulation.
***************************************************************************/
void brkthru_vh_stop(void)
{
osd_free_bitmap(tmpbitmap);
free(dirtybuffer);
}
WRITE_HANDLER( brkthru_1800_w )
{
if (offset == 0) /* low 8 bits of scroll */
bgscroll = (bgscroll & 0x100) | data;
else if (offset == 1)
{
int bankaddress;
unsigned char *RAM = memory_region(REGION_CPU1);
/* bit 0-2 = ROM bank select */
bankaddress = 0x10000 + (data & 0x07) * 0x2000;
cpu_setbank(1,&RAM[bankaddress]);
/* bit 3-5 = background tiles color code */
if (((data & 0x38) >> 2) != bgbasecolor)
{
bgbasecolor = (data & 0x38) >> 2;
memset(dirtybuffer,1,videoram_size);
}
/* bit 6 = screen flip */
if (flipscreen != (data & 0x40))
{
flipscreen = data & 0x40;
memset(dirtybuffer,1,videoram_size);
}
/* bit 7 = high bit of scroll */
bgscroll = (bgscroll & 0xff) | ((data & 0x80) << 1);
}
}
/***************************************************************************
Draw the game screen in the given osd_bitmap.
Do NOT call osd_update_display() from this function, it will be called by
the main emulation engine.
***************************************************************************/
void brkthru_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
int offs;
/* for every character in the Video RAM, check if it has been modified */
/* since last time and update it accordingly. */
for (offs = videoram_size - 2;offs >= 0;offs -= 2)
{
if (dirtybuffer[offs] || dirtybuffer[offs+1])
{
int sx,sy,code;
dirtybuffer[offs] = dirtybuffer[offs+1] = 0;
sx = (offs/2) / 16;
sy = (offs/2) % 16;
if (flipscreen)
{
sx = 31 - sx;
sy = 15 - sy;
}
code = videoram[offs] + 256 * (videoram[offs+1] & 3);
drawgfx(tmpbitmap,Machine->gfx[1 + (code >> 7)],
code & 0x7f,
bgbasecolor + ((videoram[offs+1] & 0x04) >> 2),
flipscreen,flipscreen,
16*sx,16*sy,
0,TRANSPARENCY_NONE,0);
}
}
/* copy the background graphics */
{
int scroll;
if (flipscreen) scroll = 256 + bgscroll;
else scroll = -bgscroll;
copyscrollbitmap(bitmap,tmpbitmap,1,&scroll,0,0,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
}
/* Draw the sprites. Note that it is important to draw them exactly in this */
/* order, to have the correct priorities. */
for (offs = 0;offs < spriteram_size; offs += 4)
{
if (spriteram[offs] & 0x01) /* enable */
{
int sx,sy,code,color;
/* the meaning of bit 3 of [offs] is unknown */
sx = 240 - spriteram[offs+3];
if (sx < -7) sx += 256;
sy = 240 - spriteram[offs+2];
code = spriteram[offs+1] + 128 * (spriteram[offs] & 0x06);
color = (spriteram[offs] & 0xe0) >> 5;
if (flipscreen)
{
sx = 240 - sx;
sy = 240 - sy;
}
if (spriteram[offs] & 0x10) /* double height */
{
drawgfx(bitmap,Machine->gfx[9],
code & ~1,
color,
flipscreen,flipscreen,
sx,flipscreen? sy + 16 : sy - 16,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
drawgfx(bitmap,Machine->gfx[9],
code | 1,
color,
flipscreen,flipscreen,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
/* redraw with wraparound */
drawgfx(bitmap,Machine->gfx[9],
code & ~1,
color,
flipscreen,flipscreen,
sx,(flipscreen? sy + 16 : sy - 16) + 256,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
drawgfx(bitmap,Machine->gfx[9],
code | 1,
color,
flipscreen,flipscreen,
sx,sy + 256,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
else
{
drawgfx(bitmap,Machine->gfx[9],
code,
color,
flipscreen,flipscreen,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
/* redraw with wraparound */
drawgfx(bitmap,Machine->gfx[9],
code,
color,
flipscreen,flipscreen,
sx,sy + 256,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
}
}
/* draw the frontmost playfield. They are characters, but draw them as sprites */
for (offs = brkthru_videoram_size - 1;offs >= 0;offs--)
{
int sx,sy;
sx = offs % 32;
sy = offs / 32;
if (flipscreen)
{
sx = 31 - sx;
sy = 31 - sy;
}
drawgfx(bitmap,Machine->gfx[0],
brkthru_videoram[offs],
0,
flipscreen,flipscreen,
8*sx,8*sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
}