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AmigActive 10
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AACD 10.iso
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vidhrdw
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frogger.c
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C/C++ Source or Header
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2000-04-04
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8KB
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316 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
static int flipscreen;
unsigned char *frogger_attributesram;
/* Cocktail mode implemented by Chad Hendrickson, July 26, 1999 */
/***************************************************************************
Convert the color PROMs into a more useable format.
Frogger has one 32 bytes palette PROM, 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
Additionally, there is a bit which is 1 in the upper half of the display
(136 lines? I'm not sure of the exact value); it is connected to blue
through a 470 ohm resistor. It is used to make the river blue instead of
black.
***************************************************************************/
void frogger_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
int i;
for (i = 0;i < 32;i++)
{
int bit0,bit1,bit2;
bit0 = (color_prom[i] >> 0) & 0x01;
bit1 = (color_prom[i] >> 1) & 0x01;
bit2 = (color_prom[i] >> 2) & 0x01;
palette[3*i] = 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[3*i + 1] = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
bit0 = 0;
bit1 = (color_prom[i] >> 6) & 0x01;
bit2 = (color_prom[i] >> 7) & 0x01;
palette[3*i + 2] = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
}
/* use an otherwise unused pen for the river background */
palette[3*4] = 0;
palette[3*4 + 1] = 0;
palette[3*4 + 2] = 0x47;
/* normal */
for (i = 0;i < 4 * 8;i++)
{
if (i & 3) colortable[i] = i;
else colortable[i] = 0;
}
/* blue background (river) */
for (i = 4 * 8;i < 4 * 16;i++)
{
if (i & 3) colortable[i] = i - 4*8;
else colortable[i] = 4;
}
}
WRITE_HANDLER( frogger_attributes_w )
{
if ((offset & 1) && frogger_attributesram[offset] != data)
{
int i;
for (i = offset / 2;i < videoram_size;i += 32)
dirtybuffer[i] = 1;
}
frogger_attributesram[offset] = data;
}
WRITE_HANDLER( frogger_flipscreen_w )
{
if (flipscreen != (data & 1))
{
flipscreen = data & 1;
memset(dirtybuffer,1,videoram_size);
}
}
/***************************************************************************
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 frogger_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
int i,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,col;
dirtybuffer[offs] = 0;
sx = offs % 32;
sy = offs / 32;
col = frogger_attributesram[2 * sx + 1] & 7;
col = ((col >> 1) & 0x03) | ((col << 2) & 0x04);
if (flipscreen)
{
sx = 31 - sx;
sy = 31 - sy;
drawgfx(tmpbitmap,Machine->gfx[0],
videoram[offs],
col + (sx >= 16 ? 8 : 0), /* blue background in the lower 128 lines */
flipscreen,flipscreen,8*sx,8*sy,
0,TRANSPARENCY_NONE,0);
}
else
{
drawgfx(tmpbitmap,Machine->gfx[0],
videoram[offs],
col + (sx <= 15 ? 8 : 0), /* blue background in the upper 128 lines */
flipscreen,flipscreen,8*sx,8*sy,
0,TRANSPARENCY_NONE,0);
}
}
}
/* copy the temporary bitmap to the screen */
{
int scroll[32],s;
for (i = 0;i < 32;i++)
{
s = frogger_attributesram[2 * i];
if (flipscreen)
{
scroll[31-i] = (((s << 4) & 0xf0) | ((s >> 4) & 0x0f));
}
else
{
scroll[i] = -(((s << 4) & 0xf0) | ((s >> 4) & 0x0f));
}
}
copyscrollbitmap(bitmap,tmpbitmap,0,0,32,scroll,&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)
{
if (spriteram[offs + 3] != 0)
{
int x,y,col;
x = spriteram[offs + 3];
y = spriteram[offs];
y = ((y << 4) & 0xf0) | ((y >> 4) & 0x0f);
col = spriteram[offs + 2] & 7;
col = ((col >> 1) & 0x03) | ((col << 2) & 0x04);
if (flipscreen)
{
x = 242 - x;
y = 240 - y;
drawgfx(bitmap,Machine->gfx[1],
spriteram[offs + 1] & 0x3f,
col,
!(spriteram[offs + 1] & 0x40),!(spriteram[offs + 1] & 0x80),
x,30*8 - y,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
else
{
drawgfx(bitmap,Machine->gfx[1],
spriteram[offs + 1] & 0x3f,
col,
spriteram[offs + 1] & 0x40,spriteram[offs + 1] & 0x80,
x,30*8 - y,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
}
}
}
/* the alternate version doesn't have the sprite & scroll registers mangling, */
/* but it still has the color code mangling. */
void frogger2_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
int i,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,col;
dirtybuffer[offs] = 0;
sx = offs % 32;
sy = offs / 32;
col = frogger_attributesram[2 * sx + 1] & 7;
col = ((col >> 1) & 0x03) | ((col << 2) & 0x04);
if (flipscreen)
{
sx = 31 - sx;
sy = 31 - sy;
drawgfx(tmpbitmap,Machine->gfx[0],
videoram[offs],
col + (sx >= 16 ? 8 : 0), /* blue background in the lower 128 lines */
flipscreen,flipscreen,8*sx,8*sy,
0,TRANSPARENCY_NONE,0);
}
else
{
drawgfx(tmpbitmap,Machine->gfx[0],
videoram[offs],
col + (sx <= 15 ? 8 : 0), /* blue background in the upper 128 lines */
flipscreen,flipscreen,8*sx,8*sy,
0,TRANSPARENCY_NONE,0);
}
}
}
/* copy the temporary bitmap to the screen */
{
int scroll[32];
for (i = 0;i < 32;i++)
if (flipscreen)
{
scroll[31-i] = frogger_attributesram[2 * i];
}
else
{
scroll[i] = -frogger_attributesram[2 * i];
}
copyscrollbitmap(bitmap,tmpbitmap,0,0,32,scroll,&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)
{
if (spriteram[offs + 3] != 0)
{
int x,y,col;
x = spriteram[offs + 3];
y = spriteram[offs];
col = spriteram[offs + 2] & 7;
col = ((col >> 1) & 0x03) | ((col << 2) & 0x04);
if (flipscreen)
{
x = 242 - x;
y = 240 - y;
drawgfx(bitmap,Machine->gfx[1],
spriteram[offs + 1] & 0x3f,
col,
!(spriteram[offs + 1] & 0x40),!(spriteram[offs + 1] & 0x80),
x,30*8 - y,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
else
{
drawgfx(bitmap,Machine->gfx[1],
spriteram[offs + 1] & 0x3f,
col,
spriteram[offs + 1] & 0x40,spriteram[offs + 1] & 0x80,
x,30*8 - y,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
}
}
}