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AmigActive 10
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vidhrdw
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gberet.c
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C/C++ Source or Header
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2000-04-04
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7KB
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295 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
unsigned char *gberet_videoram,*gberet_colorram;
unsigned char *gberet_spritebank;
unsigned char *gberet_scrollram;
static struct tilemap *bg_tilemap;
static int interruptenable;
static int flipscreen;
static int sprites_type;
/***************************************************************************
Convert the color PROMs into a more useable format.
Green Beret has a 32 bytes palette PROM and two 256 bytes color lookup table
PROMs (one for sprites, one for characters).
The palette PROM is connected to the RGB output, this way:
bit 7 -- 220 ohm resistor -- BLUE
-- 470 ohm resistor -- BLUE
-- 220 ohm resistor -- GREEN
-- 470 ohm resistor -- GREEN
-- 1 kohm resistor -- GREEN
-- 220 ohm resistor -- RED
-- 470 ohm resistor -- RED
bit 0 -- 1 kohm resistor -- RED
***************************************************************************/
void gberet_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;
bit0 = (*color_prom >> 0) & 0x01;
bit1 = (*color_prom >> 1) & 0x01;
bit2 = (*color_prom >> 2) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
bit0 = (*color_prom >> 3) & 0x01;
bit1 = (*color_prom >> 4) & 0x01;
bit2 = (*color_prom >> 5) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
bit0 = 0;
bit1 = (*color_prom >> 6) & 0x01;
bit2 = (*color_prom >> 7) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
color_prom++;
}
for (i = 0;i < TOTAL_COLORS(1);i++)
{
if (*color_prom & 0x0f) COLOR(1,i) = *color_prom & 0x0f;
else COLOR(1,i) = 0;
color_prom++;
}
for (i = 0;i < TOTAL_COLORS(0);i++)
{
COLOR(0,i) = (*(color_prom++) & 0x0f) + 0x10;
}
}
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static void get_tile_info(int tile_index)
{
unsigned char attr = gberet_colorram[tile_index];
SET_TILE_INFO(0,gberet_videoram[tile_index] + ((attr & 0x40) << 2),attr & 0x0f)
tile_info.flags = TILE_FLIPYX((attr & 0x30) >> 4) | TILE_SPLIT((attr & 0x80) >> 7);
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
int gberet_vh_start(void)
{
bg_tilemap = tilemap_create(get_tile_info,tilemap_scan_rows,TILEMAP_SPLIT,8,8,64,32);
if (!bg_tilemap)
return 0;
bg_tilemap->transmask[0] = 0x0001; /* split type 0 has pen 1 transparent in front half */
bg_tilemap->transmask[1] = 0xffff; /* split type 1 is totally transparent in front half */
tilemap_set_scroll_rows(bg_tilemap,32);
return 0;
}
void init_gberet(void)
{
sprites_type = 0;
}
void init_gberetb(void)
{
sprites_type = 1;
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE_HANDLER( gberet_videoram_w )
{
if (gberet_videoram[offset] != data)
{
gberet_videoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset);
}
}
WRITE_HANDLER( gberet_colorram_w )
{
if (gberet_colorram[offset] != data)
{
gberet_colorram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset);
}
}
WRITE_HANDLER( gberet_e044_w )
{
/* bit 0 enables interrupts */
interruptenable = data & 1;
/* bit 3 flips screen */
flipscreen = data & 0x08;
tilemap_set_flip(ALL_TILEMAPS,flipscreen ? (TILEMAP_FLIPY | TILEMAP_FLIPX) : 0);
/* don't know about the other bits */
}
WRITE_HANDLER( gberet_scroll_w )
{
int scroll;
gberet_scrollram[offset] = data;
scroll = gberet_scrollram[offset & 0x1f] | (gberet_scrollram[offset | 0x20] << 8);
tilemap_set_scrollx(bg_tilemap,offset & 0x1f,scroll);
}
WRITE_HANDLER( gberetb_scroll_w )
{
if (offset) data |= 0x100;
for (offset = 6;offset < 29;offset++)
tilemap_set_scrollx(bg_tilemap,offset,data + 64-8);
}
int gberet_interrupt(void)
{
if (cpu_getiloops() == 0) return interrupt();
else if (cpu_getiloops() % 2)
{
if (interruptenable) return nmi_interrupt();
}
return ignore_interrupt();
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites0(struct osd_bitmap *bitmap)
{
int offs;
unsigned char *sr;
if (*gberet_spritebank & 0x08)
sr = spriteram_2;
else sr = spriteram;
for (offs = 0;offs < spriteram_size;offs += 4)
{
if (sr[offs+3])
{
int sx,sy,flipx,flipy;
sx = sr[offs+2] - 2*(sr[offs+1] & 0x80);
sy = sr[offs+3];
if (sprites_type) sy = 240 - sy;
flipx = sr[offs+1] & 0x10;
flipy = sr[offs+1] & 0x20;
if (flipscreen)
{
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,Machine->gfx[1],
sr[offs+0] + ((sr[offs+1] & 0x40) << 2),
sr[offs+1] & 0x0f,
flipx,flipy,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_COLOR,0);
}
}
}
static void draw_sprites1(struct osd_bitmap *bitmap)
{
int offs;
unsigned char *sr;
sr = spriteram;
for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
{
if (sr[offs+1])
{
int sx,sy,flipx,flipy;
sx = sr[offs+2] - 2*(sr[offs+3] & 0x80);
sy = sr[offs+1];
if (sprites_type) sy = 240 - sy;
flipx = sr[offs+3] & 0x10;
flipy = sr[offs+3] & 0x20;
if (flipscreen)
{
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,Machine->gfx[1],
sr[offs+0] + ((sr[offs+3] & 0x40) << 2),
sr[offs+3] & 0x0f,
flipx,flipy,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_COLOR,0);
}
}
}
void gberet_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
tilemap_update(ALL_TILEMAPS);
tilemap_render(ALL_TILEMAPS);
tilemap_draw(bitmap,bg_tilemap,TILEMAP_BACK);
if (sprites_type == 0) draw_sprites0(bitmap); /* original */
else draw_sprites1(bitmap); /* bootleg */
tilemap_draw(bitmap,bg_tilemap,TILEMAP_FRONT);
}