ref: a7a315bff61bff58a9c918294f53c1e87d7ae7bb
dir: /sys/src/games/md/vdp.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "../eui.h"
#include "dat.h"
#include "fns.h"
u16int vdpstat = 0x3400;
int vdpx, vdpy, vdpyy, frame, intla;
u16int hctr;
static int xmax, xdisp;
static int sx, snx, col, pri, lum;
enum { DARK, NORM, BRIGHT };
enum { ymax = 262, yvbl = 234 };
void
vdpmode(void)
{
if((reg[MODE4] & WIDE) != 0){
xmax = 406;
xdisp = 320;
}else{
xdisp = 256;
xmax = 342;
}
intla = (reg[MODE4] & 6) == 6;
}
static void
pixeldraw(int x, int y, int v)
{
u32int *p;
union { u32int l; u8int b[4]; } u;
p = (u32int *)pic + (x + y * 320) * scale;
u.b[0] = v >> 16;
u.b[1] = v >> 8;
u.b[2] = v;
u.b[3] = 0;
switch(scale){
case 16: *p++ = u.l;
case 15: *p++ = u.l;
case 14: *p++ = u.l;
case 13: *p++ = u.l;
case 12: *p++ = u.l;
case 11: *p++ = u.l;
case 10: *p++ = u.l;
case 9: *p++ = u.l;
case 8: *p++ = u.l;
case 7: *p++ = u.l;
case 6: *p++ = u.l;
case 5: *p++ = u.l;
case 4: *p++ = u.l;
case 3: *p++ = u.l;
case 2: *p++ = u.l; /* intla ignored */
default: *p = u.l;
}
}
static u32int
shade(u32int v, int l)
{
if(l == 1)
return v;
if(l == 2)
return v << 1 & 0xefefef;
return v >> 1 & 0xf7f7f7;
}
static void
pixel(int v, int p)
{
if(p >= pri){
col = v;
pri = p;
}
}
struct pctxt {
u8int ws, w, hs, h;
u16int tx, ty;
u8int tnx, tny;
u16int t;
u32int c;
} pctxt[3];
int lwin, rwin;
static void
tile(struct pctxt *p)
{
u16int a;
int y;
switch(p - pctxt){
default: a = (reg[PANT] & 0x38) << 9; break;
case 1: a = (reg[PBNT] & 7) << 12; break;
case 2: a = (reg[PWNT] & 0x3e) << 9; break;
}
a += p->ty << p->ws;
a += p->tx;
p->t = vram[a];
y = p->tny;
if(intla){
if((p->t & 0x1000) != 0)
y = 15 - y;
a = (p->t & 0x7ff) << 5 | y << 1;
}else{
if((p->t & 0x1000) != 0)
y = 7 - y;
a = (p->t & 0x7ff) << 4 | y << 1;
}
p->c = vram[a] << 16 | vram[a+1];
}
static void
planeinit(void)
{
static int szs[] = {5, 6, 6, 7};
int v, a, i;
struct pctxt *p;
pctxt[0].hs = pctxt[1].hs = szs[reg[PLSIZ] >> 4 & 3];
pctxt[0].ws = pctxt[1].ws = szs[reg[PLSIZ] & 3];
pctxt[2].ws = (reg[MODE4] & WIDE) != 0 ? 6 : 5;
pctxt[2].hs = 5;
for(i = 0; i <= 2; i++){
pctxt[i].h = 1<<pctxt[i].hs;
pctxt[i].w = 1<<pctxt[i].ws;
}
a = reg[HORSCR] << 9 & 0x7fff;
switch(reg[MODE3] & 3){
case 1: a += vdpy << 1 & 0xe; break;
case 2: a += vdpy << 1 & 0xff0; break;
case 3: a += vdpy << 1 & 0xffe; break;
}
for(i = 0; i < 2; i++){
p = pctxt + i;
v = -(vram[a + i] & 0x3ff);
p->tnx = v & 7;
p->tx = v >> 3 & pctxt[i].w - 1;
if(intla){
v = vsram[i] + vdpyy;
p->tny = v & 15;
p->ty = v >> 4 & pctxt[i].h - 1;
}else{
v = vsram[i] + vdpy;
p->tny = v & 7;
p->ty = v >> 3 & pctxt[i].h - 1;
}
tile(p);
if(p->tnx != 0)
if((p->t & 0x800) != 0)
p->c >>= p->tnx << 2;
else
p->c <<= p->tnx << 2;
}
sx = 0;
snx = 0;
v = reg[WINV] << 3 & 0xf8;
if((reg[WINV] & 0x80) != 0 ? vdpy < v : vdpy >= v){
lwin = 0;
rwin = reg[WINH] << 4 & 0x1f0;
if((reg[WINH] & 0x80) != 0){
lwin = rwin;
rwin = 320;
}
}else{
lwin = 0;
rwin = 320;
}
if(rwin > lwin){
p = pctxt + 2;
p->tx = lwin >> 3 & pctxt[2].w - 1;
p->tnx = lwin & 7;
p->tny = vdpy & 7;
p->ty = vdpy >> 3 & pctxt[2].h - 1;
tile(p);
}
}
static void
plane(int n, int vis)
{
struct pctxt *p;
u8int v, pr;
p = pctxt + n;
if((p->t & 0x800) != 0){
v = p->c & 15;
p->c >>= 4;
}else{
v = p->c >> 28;
p->c <<= 4;
}
if(vis != 0){
if(v != 0){
v |= p->t >> 9 & 48;
pr = 2 - (n & 1) + (p->t >> 13 & 4);
pixel(v, pr);
}
lum |= p->t >> 15;
}
if(++p->tnx == 8){
p->tnx = 0;
if(++p->tx == p->w)
p->tx = 0;
tile(pctxt + n);
}
}
static void
planes(void)
{
int i, w;
u16int v;
if((reg[MODE3] & 4) != 0 && ++snx == 16){
snx = 0;
sx++;
for(i = 0; i < 2; i++){
v = vsram[sx + i] + vdpy;
pctxt[i].tny = v & 7;
pctxt[i].ty = v >> 3 & pctxt[i].h - 1;
}
}
w = vdpx < rwin && vdpx >= lwin;
plane(0, !w);
plane(1, 1);
if(w)
plane(2, 1);
}
static struct sprite {
u16int y, x;
u8int w, h;
u16int t;
u32int c[4];
} spr[21], *lsp;
static void
spritesinit(void)
{
u16int t, *p, dy, c;
u32int v;
int i, ns, np, nt;
struct sprite *q;
t = (reg[SPRTAB] << 8 & 0x7f00);
p = vram + t;
q = spr;
ns = (reg[MODE4] & WIDE) != 0 ? 20 : 16;
np = 0;
nt = 0;
do{
if(intla){
q->y = (p[0] & 0x3ff) - 256;
q->h = (p[1] >> 8 & 3) + 1 << 4;
dy = vdpyy - q->y;
}else{
q->y = (p[0] & 0x3ff) - 128;
q->h = (p[1] >> 8 & 3) + 1 << 3;
dy = vdpy - q->y;
}
if(dy >= q->h)
continue;
q->t = p[2];
if((q->t & 0x1000) != 0)
dy = q->h + ~dy;
q->x = (p[3] & 0x3ff) - 128;
if(q->x == 0xff80)
break;
q->w = (p[1] >> 10 & 3) + 1 << 3;
c = ((q->t & 0x7ff) << 4+intla) + (dy << 1);
for(i = 0; i < q->w >> 3 && np < xdisp; i++){
v = vram[c] << 16 | vram[(u16int)(c+1)];
c += q->h << 1;
if((q->t & 0x800) != 0)
q->c[(q->w >> 3) - 1 - i] = v;
else
q->c[i] = v;
np += 8;
}
if((u16int)-q->x < q->w){
i = -(s16int)q->x;
if((q->t & 0x800) != 0)
q->c[i>>3] >>= (i & 7) << 2;
else
q->c[i>>3] <<= (i & 7) << 2;
}
if(++q == spr + ns || np >= xdisp){
vdpstat |= STATOVR;
break;
}
}while(p = vram + (u16int)(t + ((p[1] & 0x7f) << 2)), p - vram != t && ++nt < 80);
lsp = q;
}
static void
sprites(void)
{
struct sprite *p;
u16int dx;
int v, col, set;
u32int *c;
set = 0;
col = 0;
for(p = spr; p < lsp; p++){
dx = vdpx - p->x;
if(dx >= p->w)
continue;
c = p->c + (dx >> 3);
if((p->t & 0x800) != 0){
v = *c & 15;
*c >>= 4;
}else{
v = *c >> 28;
*c <<= 4;
}
if(v != 0)
if(set != 0)
vdpstat |= STATCOLL;
else{
set = 1 | p->t & 0x8000;
col = p->t >> 9 & 48 | v;
}
}
if(set)
if((reg[MODE4] & SHI) != 0)
if((col & 0xfe) == 0x3e)
lum = col & 1;
else{
pixel(col, set >> 13 | 2);
if((col & 0xf) == 0xe)
lum = 1;
else
lum |= set >> 15;
}
else
pixel(col, set >> 13 | 2);
}
void
vdpstep(void)
{
u32int v;
if(vdpx == 0){
planeinit();
spritesinit();
}
if(vdpx < 320 && vdpy < 224)
if(vdpx < xdisp){
col = reg[BGCOL] & 0x3f;
pri = 0;
lum = 0;
planes();
sprites();
if((reg[MODE2] & 0x40) != 0 && (vdpx >= 8 || (reg[MODE1] & 0x20) == 0)){
v = cramc[col];
if((reg[MODE4] & SHI) != 0)
v = shade(v, lum);
pixeldraw(vdpx, vdpy, v);
}else
pixeldraw(vdpx, vdpy, 0);
}else
pixeldraw(vdpx, vdpy, 0xcccccc);
if(++vdpx >= xmax){
z80irq = 0;
vdpx = 0;
if(++vdpy >= ymax){
vdpy = 0;
irq &= ~INTVBL;
vdpstat ^= STATFR;
vdpstat &= ~(STATINT | STATVBL | STATOVR | STATCOLL);
flush();
}
if(intla)
vdpyy = vdpy << 1 | frame;
if(vdpy == 0 || vdpy >= 225)
hctr = reg[HORCTR];
else
if(hctr-- == 0){
if((reg[MODE1] & IE1) != 0)
irq |= INTHOR;
hctr = reg[HORCTR];
}
if(vdpy == yvbl){
vdpstat |= STATVBL | STATINT;
frame ^= 1;
z80irq = 1;
if((reg[MODE2] & IE0) != 0)
irq |= INTVBL;
}
}
}