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AmigActive 10
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AACD 10.iso
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vidhrdw
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mermaid.c
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C/C++ Source or Header
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2000-05-04
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5KB
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191 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
unsigned char* mermaid_background_videoram;
unsigned char* mermaid_foreground_videoram;
unsigned char* mermaid_foreground_colorram;
unsigned char* mermaid_background_scrollram;
unsigned char* mermaid_foreground_scrollram;
static struct rectangle spritevisiblearea =
{
0*8, 26*8-1,
2*8, 30*8-1
};
/***************************************************************************
Convert the color PROMs into a more useable format.
I'm not sure about the resistor value, I'm using the Galaxian ones.
***************************************************************************/
void mermaid_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
#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])
int i;
/* first, the char acter/sprite palette */
for (i = 0;i < TOTAL_COLORS(0); 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++;
}
/* blue background */
*(palette++) = 0;
*(palette++) = 0;
*(palette++) = 0xff;
/* set up background palette */
COLOR(2,0) = 32;
COLOR(2,1) = 33;
COLOR(2,2) = 64;
COLOR(2,3) = 33;
}
/***************************************************************************
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 mermaid_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
int offs;
/* for every character in the backround RAM, check if it has been modified */
/* since last time and update it accordingly. */
for (offs = 0; offs < videoram_size; offs ++)
{
int code,sx,sy;
sy = 8 * (offs / 32);
sx = 8 * (offs % 32);
code = mermaid_background_videoram[offs];
drawgfx(tmpbitmap,Machine->gfx[2],
code,
(sx >= 26*8) ? 0 : 1,
0,0,
sx,sy,
0,TRANSPARENCY_NONE,0);
}
/* copy the temporary bitmap to the screen */
{
int i, scroll[32];
for (i = 0;i < 32;i++)
{
scroll[i] = -mermaid_background_scrollram[i];
}
copyscrollbitmap(bitmap,tmpbitmap,0,0,32,scroll,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
}
/* draw the front layer. They are characters, but draw them as sprites */
for (offs = 0; offs < videoram_size; offs ++)
{
int code,sx,sy;
sy = 8 * (offs / 32);
sx = (offs % 32);
sy = (sy - mermaid_foreground_scrollram[sx]) & 0xff;
code = mermaid_foreground_videoram[offs] | ((mermaid_foreground_colorram[offs] & 0x30) << 4);
drawgfx(bitmap,Machine->gfx[0],
code,
mermaid_foreground_colorram[offs] & 0x0f,
0,0,
8*sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
/* draw the sprites */
for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
{
#ifdef MAME_DEBUG
extern int debug_key_pressed;
#endif
UINT8 flipx,flipy,sx,sy,code,bank = 0;
sx = spriteram[offs + 3] + 1;
sy = 240 - spriteram[offs + 1];
flipx = spriteram[offs + 0] & 0x40;
flipy = spriteram[offs + 0] & 0x80;
/* this doesn't look correct. Oh really? Maybe there is a PROM. */
switch (spriteram[offs + 2] & 0xf0)
{
case 0x00: bank = 2; break;
case 0x10: bank = 1; break;
case 0x20: bank = 2; break;
case 0x30: bank = 3; break;
case 0x50: bank = 1; break;
case 0x60: bank = 2; break;
case 0x80: bank = 0; break;
case 0x90: bank = 3; break;
case 0xa0: bank = 2; break;
case 0xb0: bank = 3; break;
#ifdef MAME_DEBUG
default: debug_key_pressed = 1; break;
#endif
}
code = (spriteram[offs + 0] & 0x3f) | (bank << 6);
drawgfx(bitmap,Machine->gfx[1],
code,
spriteram[offs + 2] & 0x0f,
flipx, flipy,
sx, sy,
&spritevisiblearea,TRANSPARENCY_PEN,0);
}
}