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vidhrdw
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blstroid.c
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C/C++ Source or Header
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2000-04-04
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/***************************************************************************
vidhrdw/blstroid.c
Functions to emulate the video hardware of the machine.
****************************************************************************
Playfield encoding
------------------
1 16-bit word is used
Word 1:
Bits 13-15 = palette
Bits 0-12 = image number
Motion Object encoding
----------------------
4 16-bit words are used
Word 1:
Bits 7-15 = vertical position
Bits 0-3 = vertical size of the object, in tiles
Word 2:
Bit 15 = horizontal flip
Bit 14 = vertical flip
Bits 0-13 = image index
Word 3:
Bits 3-11 = link to the next motion object
Word 4:
Bits 6-15 = horizontal position
Bits 0-3 = motion object palette
***************************************************************************/
#include "driver.h"
#include "machine/atarigen.h"
#include "vidhrdw/generic.h"
#define XCHARS 40
#define YCHARS 30
#define XDIM (XCHARS*16)
#define YDIM (YCHARS*8)
/*************************************
*
* Statics
*
*************************************/
static UINT32 priority[8];
/*************************************
*
* Prototypes
*
*************************************/
static const UINT8 *update_palette(void);
static void pf_color_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *data);
static void pf_render_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *data);
static void pf_overrender_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *data);
static void mo_color_callback(const UINT16 *data, const struct rectangle *clip, void *param);
static void mo_render_callback(const UINT16 *data, const struct rectangle *clip, void *param);
/*************************************
*
* Generic video system start
*
*************************************/
int blstroid_vh_start(void)
{
static struct atarigen_mo_desc mo_desc =
{
512, /* maximum number of MO's */
8, /* number of bytes per MO entry */
2, /* number of bytes between MO words */
0, /* ignore an entry if this word == 0xffff */
2, 3, 0x1ff, /* link = (data[linkword] >> linkshift) & linkmask */
0 /* render in reverse link order */
};
static struct atarigen_pf_desc pf_desc =
{
16, 8, /* width/height of each tile */
64, 64, /* number of tiles in each direction */
1 /* non-scrolling */
};
/* reset statics */
memset(priority, 0, sizeof(priority));
/* initialize the playfield */
if (atarigen_pf_init(&pf_desc))
return 1;
/* initialize the motion objects */
if (atarigen_mo_init(&mo_desc))
{
atarigen_pf_free();
return 1;
}
return 0;
}
/*************************************
*
* Video system shutdown
*
*************************************/
void blstroid_vh_stop(void)
{
atarigen_pf_free();
atarigen_mo_free();
}
/*************************************
*
* Periodic scanline updater
*
*************************************/
static void irq_off(int param)
{
atarigen_scanline_int_ack_w(0, 0);
}
void blstroid_scanline_update(int scanline)
{
int offset = (scanline / 8) * 0x80 + 0x50;
/* update motion objects */
if (scanline == 0)
atarigen_mo_update(atarigen_spriteram, 0, scanline);
/* check for interrupts */
if (offset < atarigen_playfieldram_size)
if (READ_WORD(&atarigen_playfieldram[offset]) & 0x8000)
{
/* generate the interrupt */
atarigen_scanline_int_gen();
atarigen_update_interrupts();
/* also set a timer to turn ourself off */
timer_set(cpu_getscanlineperiod(), 0, irq_off);
}
}
/*************************************
*
* Playfield RAM write handler
*
*************************************/
WRITE_HANDLER( blstroid_playfieldram_w )
{
int oldword = READ_WORD(&atarigen_playfieldram[offset]);
int newword = COMBINE_WORD(oldword, data);
if (oldword != newword)
{
WRITE_WORD(&atarigen_playfieldram[offset], newword);
atarigen_pf_dirty[offset / 2] = 1;
}
}
/*************************************
*
* Priority RAM write handler
*
*************************************/
WRITE_HANDLER( blstroid_priorityram_w )
{
int shift, which;
/* pick which playfield palette to look at */
which = (offset >> 5) & 7;
/* upper 16 bits are for H == 1, lower 16 for H == 0 */
shift = (offset >> 4) & 0x10;
shift += (offset >> 1) & 0x0f;
/* set or clear the appropriate bit */
priority[which] = (priority[which] & ~(1 << shift)) | ((data & 1) << shift);
}
/*************************************
*
* Main refresh
*
*************************************/
void blstroid_vh_screenrefresh(struct osd_bitmap *bitmap, int full_refresh)
{
/* remap if necessary */
if (update_palette())
memset(atarigen_pf_dirty, 1, atarigen_playfieldram_size / 2);
/* draw the playfield */
atarigen_pf_process(pf_render_callback, bitmap, &Machine->drv->visible_area);
/* render the motion objects */
atarigen_mo_process(mo_render_callback, bitmap);
/* update onscreen messages */
atarigen_update_messages();
}
/*************************************
*
* Palette management
*
*************************************/
static const UINT8 *update_palette(void)
{
UINT16 pf_map[8], mo_map[16];
int i, j;
/* reset color tracking */
memset(mo_map, 0, sizeof(mo_map));
memset(pf_map, 0, sizeof(pf_map));
palette_init_used_colors();
/* update color usage for the playfield */
atarigen_pf_process(pf_color_callback, pf_map, &Machine->drv->visible_area);
/* update color usage for the mo's */
atarigen_mo_process(mo_color_callback, mo_map);
/* rebuild the playfield palette */
for (i = 0; i < 8; i++)
{
UINT16 used = pf_map[i];
if (used)
for (j = 0; j < 16; j++)
if (used & (1 << j))
palette_used_colors[0x100 + i * 16 + j] = PALETTE_COLOR_USED;
}
/* rebuild the motion object palette */
for (i = 0; i < 16; i++)
{
UINT16 used = mo_map[i];
if (used)
{
palette_used_colors[0x000 + i * 16 + 0] = PALETTE_COLOR_TRANSPARENT;
for (j = 1; j < 16; j++)
if (used & (1 << j))
palette_used_colors[0x000 + i * 16 + j] = PALETTE_COLOR_USED;
}
}
return palette_recalc();
}
/*************************************
*
* Playfield palette
*
*************************************/
static void pf_color_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *param)
{
const unsigned int *usage = Machine->gfx[0]->pen_usage;
UINT16 *colormap = param;
int x, y;
/* standard loop over tiles */
for (y = tiles->min_y; y != tiles->max_y; y = (y + 1) & 63)
for (x = tiles->min_x; x != tiles->max_x; x = (x + 1) & 63)
{
int offs = y * 64 + x;
int data = READ_WORD(&atarigen_playfieldram[offs * 2]);
int code = data & 0x1fff;
int color = data >> 13;
/* mark the colors used by this tile */
colormap[color] |= usage[code];
}
}
/*************************************
*
* Playfield rendering
*
*************************************/
static void pf_render_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *param)
{
const struct GfxElement *gfx = Machine->gfx[0];
struct osd_bitmap *bitmap = param;
int x, y;
/* standard loop over tiles */
for (y = tiles->min_y; y != tiles->max_y; y = (y + 1) & 63)
for (x = tiles->min_x; x != tiles->max_x; x = (x + 1) & 63)
{
int offs = y * 64 + x;
/* update only if dirty */
if (atarigen_pf_dirty[offs])
{
int data = READ_WORD(&atarigen_playfieldram[offs * 2]);
int code = data & 0x1fff;
int color = data >> 13;
drawgfx(atarigen_pf_bitmap, gfx, code, color, 0, 0, 16 * x, 8 * y, 0, TRANSPARENCY_NONE, 0);
atarigen_pf_dirty[offs] = 0;
}
}
/* then blast the result */
copybitmap(bitmap, atarigen_pf_bitmap, 0, 0, 0, 0, clip, TRANSPARENCY_NONE, 0);
}
/*************************************
*
* Playfield overrendering
*
*************************************/
static void pf_overrender_callback(const struct rectangle *clip, const struct rectangle *tiles, const struct atarigen_pf_state *state, void *param)
{
const struct GfxElement *gfx = Machine->gfx[0];
struct osd_bitmap *bitmap = param;
int x, y;
/* standard loop over tiles */
for (y = tiles->min_y; y != tiles->max_y; y = (y + 1) & 63)
for (x = tiles->min_x; x != tiles->max_x; x = (x + 1) & 63)
{
int offs = y * 64 + x;
int data = READ_WORD(&atarigen_playfieldram[offs * 2]);
int color = data >> 13;
/* overrender if there is a non-zero priority for this color */
/* not perfect, but works for the most obvious cases */
if (!priority[color])
{
int code = data & 0x1fff;
drawgfx(bitmap, gfx, code, color, 0, 0, 16 * x, 8 * y, clip, TRANSPARENCY_NONE, 0);
}
}
}
/*************************************
*
* Motion object palette
*
*************************************/
static void mo_color_callback(const UINT16 *data, const struct rectangle *clip, void *param)
{
const unsigned int *usage = Machine->gfx[1]->pen_usage;
UINT16 *colormap = param;
int vsize = (data[0] & 0x000f) + 1;
int code = data[1] & 0x3fff;
int color = data[3] & 0x000f;
UINT16 temp = 0;
int i;
for (i = 0; i < vsize; i++)
temp |= usage[code++];
colormap[color] |= temp;;
}
/*************************************
*
* Motion object rendering
*
*************************************/
static void mo_render_callback(const UINT16 *data, const struct rectangle *clip, void *param)
{
const struct GfxElement *gfx = Machine->gfx[1];
struct osd_bitmap *bitmap = param;
struct rectangle pf_clip;
/* extract data from the various words */
int ypos = -(data[0] >> 7);
int vsize = (data[0] & 0x000f) + 1;
int hflip = data[1] & 0x8000;
int vflip = data[1] & 0x4000;
int code = data[1] & 0x3fff;
int xpos = (data[3] >> 7) << 1;
int color = data[3] & 0x000f;
/* adjust for height */
ypos -= vsize * 8;
/* adjust the final coordinates */
xpos &= 0x3ff;
ypos &= 0x1ff;
if (xpos >= XDIM) xpos -= 0x400;
if (ypos >= YDIM) ypos -= 0x200;
/* clip the X coordinate */
if (xpos <= -16 || xpos >= XDIM)
return;
/* determine the bounding box */
atarigen_mo_compute_clip_16x8(pf_clip, xpos, ypos, 1, vsize, clip);
/* draw the motion object */
atarigen_mo_draw_16x8_strip(bitmap, gfx, code, color, hflip, vflip, xpos, ypos, vsize, clip, TRANSPARENCY_PEN, 0);
/* overrender the playfield */
atarigen_pf_process(pf_overrender_callback, bitmap, &pf_clip);
}