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AmigActive 10
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AACD 10.iso
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vidhrdw
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thepit.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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329 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
extern unsigned char *galaxian_attributesram;
static int graphics_bank = 0;
static int sound_enabled = 0;
static struct rectangle spritevisiblearea =
{
2*8+1, 32*8-1,
2*8, 30*8-1
};
static struct rectangle spritevisibleareaflipx =
{
0*8, 30*8-2,
2*8, 30*8-1
};
/***************************************************************************
Convert the color PROMs into a more useable format.
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 thepit_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
int i;
/* first of all, allocate primary colors for the background and foreground */
/* this is wrong, but I don't know where to pick the colors from */
for (i = 0;i < 8;i++)
{
*(palette++) = 0xff * ((i >> 2) & 1);
*(palette++) = 0xff * ((i >> 1) & 1);
*(palette++) = 0xff * ((i >> 0) & 1);
}
for (i = 0;i < Machine->drv->total_colors-8;i++)
{
int bit0,bit1,bit2;
bit0 = (color_prom[i] >> 0) & 0x01;
bit1 = (color_prom[i] >> 1) & 0x01;
bit2 = (color_prom[i] >> 2) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
bit0 = (color_prom[i] >> 3) & 0x01;
bit1 = (color_prom[i] >> 4) & 0x01;
bit2 = (color_prom[i] >> 5) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
bit0 = 0;
bit1 = (color_prom[i] >> 6) & 0x01;
bit2 = (color_prom[i] >> 7) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
}
for (i = 0;i < Machine->drv->total_colors-8;i++)
{
colortable[i] = i + 8;
}
}
WRITE_HANDLER( intrepid_graphics_bank_select_w )
{
if (graphics_bank != (data << 1))
{
graphics_bank = data << 1;
memset(dirtybuffer,1,videoram_size);
}
}
WRITE_HANDLER( thepit_flipx_w )
{
if (*flip_screen_x != (data & 1))
{
*flip_screen_x = data & 1;
memset(dirtybuffer,1,videoram_size);
}
}
WRITE_HANDLER( thepit_flipy_w )
{
if (*flip_screen_y != (data & 1))
{
*flip_screen_y = data & 1;
memset(dirtybuffer,1,videoram_size);
}
}
READ_HANDLER( thepit_input_port_0_r )
{
/* Read either the real or the fake input ports depending on the
horizontal flip switch. (This is how the real PCB does it) */
if (*flip_screen_x)
{
return input_port_3_r(offset);
}
else
{
return input_port_0_r(offset);
}
}
WRITE_HANDLER( thepit_sound_enable_w )
{
if (sound_enabled && !data)
{
AY8910_reset(0);
}
sound_enabled = data;
}
static void common_AY8910_w(int offset, int data,
mem_write_handler write_port,
mem_write_handler control_port)
{
/* Get out if sound is off */
if (!sound_enabled) return;
if (offset & 1)
{
write_port(0, data);
}
else
{
control_port(0, data);
}
}
WRITE_HANDLER( thepit_AY8910_0_w )
{
common_AY8910_w(offset, data, AY8910_write_port_0_w, AY8910_control_port_0_w);
}
WRITE_HANDLER( thepit_AY8910_1_w )
{
common_AY8910_w(offset, data, AY8910_write_port_1_w, AY8910_control_port_1_w);
}
/***************************************************************************
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.
***************************************************************************/
static void drawtiles(struct osd_bitmap *bitmap,int priority)
{
int offs,spacechar=0;
if (priority == 1)
{
/* find the space character */
while (Machine->gfx[0]->pen_usage[spacechar] & ~1) spacechar++;
}
/* for every character in the Video RAM, check if it has been modified */
/* since last time and update it accordingly. */
for (offs = videoram_size - 1;offs >= 0;offs--)
{
int bgcolor;
bgcolor = (colorram[offs] & 0x70) >> 4;
if ((priority == 0 && dirtybuffer[offs]) ||
(priority == 1 && bgcolor != 0 && (colorram[offs] & 0x80) == 0))
{
int sx,sy,code,bank,color;
dirtybuffer[offs] = 0;
sx = (offs % 32);
sy = 8*(offs / 32);
if (priority == 0)
{
code = videoram[offs];
bank = graphics_bank;
}
else
{
code = spacechar;
bank = 0;
sy = (sy - galaxian_attributesram[2 * sx]) & 0xff;
}
if (*flip_screen_x) sx = 31 - sx;
if (*flip_screen_y) sy = 248 - sy;
color = colorram[offs] & 0x07;
/* set up the background color */
Machine->gfx[bank]->
colortable[color * Machine->gfx[graphics_bank]->color_granularity] =
Machine->pens[bgcolor];
drawgfx(priority == 0 ? tmpbitmap : bitmap,Machine->gfx[bank],
code,
color,
*flip_screen_x,*flip_screen_y,
8*sx,sy,
0,TRANSPARENCY_NONE,0);
}
}
/* copy the temporary bitmap to the screen */
if (priority == 0)
{
int i, scroll[32];
if (*flip_screen_x)
{
for (i = 0;i < 32;i++)
{
scroll[31-i] = -galaxian_attributesram[2 * i];
if (*flip_screen_y) scroll[31-i] = -scroll[31-i];
}
}
else
{
for (i = 0;i < 32;i++)
{
scroll[i] = -galaxian_attributesram[2 * i];
if (*flip_screen_y) scroll[i] = -scroll[i];
}
}
copyscrollbitmap(bitmap,tmpbitmap,0,0,32,scroll,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
}
}
static void drawsprites(struct osd_bitmap *bitmap,int priority)
{
int offs;
/* draw low priority sprites */
for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
{
if (((spriteram[offs + 2] & 0x08) >> 3) == priority)
{
int sx,sy,flipx,flipy;
if (spriteram[offs + 0] == 0 ||
spriteram[offs + 3] == 0)
{
continue;
}
sx = (spriteram[offs+3] + 1) & 0xff;
sy = 240 - spriteram[offs];
flipx = spriteram[offs + 1] & 0x40;
flipy = spriteram[offs + 1] & 0x80;
if (*flip_screen_x)
{
sx = 242 - sx;
flipx = !flipx;
}
if (*flip_screen_y)
{
sy = 240 - sy;
flipy = !flipy;
}
/* Sprites 0-3 are drawn one pixel to the left */
if (offs <= 3*4) sy++;
drawgfx(bitmap,Machine->gfx[graphics_bank | 1],
spriteram[offs + 1] & 0x3f,
spriteram[offs + 2] & 0x07,
flipx,flipy,
sx,sy,
*flip_screen_x & 1 ? &spritevisibleareaflipx : &spritevisiblearea,TRANSPARENCY_PEN,0);
}
}
}
void thepit_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
/* low priority tiles */
drawtiles(bitmap,0);
/* low priority sprites */
drawsprites(bitmap,0);
/* high priority tiles */
drawtiles(bitmap,1);
/* high priority sprites */
drawsprites(bitmap,1);
}