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AmigActive 10
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vidhrdw
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pingpong.c
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C/C++ Source or Header
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1998-07-18
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5KB
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164 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
/* This is strange; it's unlikely that the sprites actually have a hardware */
/* clipping region, but I haven't found another way to have them masked by */
/* the characters at the top and bottom of the screen. */
static struct rectangle spritevisiblearea =
{
0*8, 32*8-1,
4*8, 29*8-1
};
/***************************************************************************
Convert the color PROMs into a more useable format.
Ping Pong has a 32 bytes palette PROM and two 256 bytes color lookup table
PROMs (one for sprites, one for characters).
I don't know for sure how the palette PROM is connected to the RGB output,
but it's probably the usual:
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 pingpong_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;
/* red component */
bit0 = (*color_prom >> 0) & 0x01;
bit1 = (*color_prom >> 1) & 0x01;
bit2 = (*color_prom >> 2) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* green component */
bit0 = (*color_prom >> 3) & 0x01;
bit1 = (*color_prom >> 4) & 0x01;
bit2 = (*color_prom >> 5) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* blue component */
bit0 = 0;
bit1 = (*color_prom >> 6) & 0x01;
bit2 = (*color_prom >> 7) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
color_prom++;
}
/* color_prom now points to the beginning of the char lookup table */
/* sprites */
for (i = 0;i < TOTAL_COLORS(1);i++)
{
int code;
int bit0,bit1,bit2,bit3;
/* the bits of the color code are in reverse order - 0123 instead of 3210 */
code = *(color_prom++) & 0x0f;
bit0 = (code >> 0) & 1;
bit1 = (code >> 1) & 1;
bit2 = (code >> 2) & 1;
bit3 = (code >> 3) & 1;
code = (bit0 << 3) | (bit1 << 2) | (bit2 << 1) | (bit3 << 0);
COLOR(1,i) = code;
}
/* characters */
for (i = 0;i < TOTAL_COLORS(0);i++)
COLOR(0,i) = (*(color_prom++) & 0x0f) + 0x10;
}
/***************************************************************************
Draw the game screen in the given osd_bitmap.
***************************************************************************/
void pingpong_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 - 1;offs >= 0;offs--)
{
if (dirtybuffer[offs])
{
int sx,sy,flipx,flipy,tchar,color;
sx = offs % 32;
sy = offs / 32;
dirtybuffer[offs] = 0;
flipx = colorram[offs] & 0x40;
flipy = colorram[offs] & 0x80;
color = colorram[offs] & 0x1F;
tchar = (videoram[offs] + ((colorram[offs] & 0x20)<<3));
drawgfx(tmpbitmap,Machine->gfx[0],
tchar,
color,
flipx,flipy,
8 * sx,8 * sy,
&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
}
}
/* copy the character mapped graphics */
copybitmap(bitmap,tmpbitmap,0,0,0,0,&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 = spriteram_size - 4;offs >= 0;offs -= 4)
{
int sx,sy,flipx,flipy,color,schar;
sx = spriteram[offs + 3];
sy = 241 - spriteram[offs + 1];
flipx = spriteram[offs] & 0x40;
flipy = spriteram[offs] & 0x80;
color = spriteram[offs] & 0x1F;
schar = spriteram[offs + 2] & 0x7F;
drawgfx(bitmap,Machine->gfx[1],
schar,
color,
flipx,flipy,
sx,sy,
&spritevisiblearea,TRANSPARENCY_COLOR,0);
}
}