ref: 586a24770c5accfadc13408ba2b617b062fb50ae
dir: /sys/src/games/gba/mem.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
uchar bios[16*KB], wram0[32*KB], wram1[256*KB];
uchar vram[96*KB];
u16int pram[512], oam[512];
uchar *rom, *back;
int nrom, nback;
u16int reg[512];
int dmaact;
enum {
DMASRC,
DMADST,
DMACNT
};
u32int dmar[16];
u8int waitst[16] = {5, 5, 5, 5, 3, 5, 5, 9, 8, 10, 10, 14};
u32int eepstart;
Var memvars[] = {
ARR(wram0), ARR(wram1), ARR(vram), ARR(pram), ARR(oam), ARR(reg),
VAR(dmaact), ARR(dmar), ARR(waitst),
{nil, 0, 0},
};
extern int cyc;
static int eepromread(void);
static void eepromwrite(int);
static u8int flashread(u16int);
static void flashwrite(u16int, u8int);
static u32int
arread(uchar *c, int n)
{
switch(n){
default:
return c[0];
case 2:
return c[0] | c[1] << 8;
case 4:
return c[0] | c[1] << 8 | c[2] << 16 | c[3] << 24;
}
}
static void
arwrite(uchar *c, u32int v, int n)
{
switch(n){
case 4:
c[3] = v >> 24;
c[2] = v >> 16;
case 2:
c[1] = v >> 8;
default:
c[0] = v;
}
}
static u32int
ar16read(u16int *c, int h, int n)
{
switch(n){
case 1:
return c[0] >> (h << 3);
default:
return c[0];
case 4:
return c[0] | c[1] << 16;
}
}
static void
ar16write(u16int *c, int h, u32int v, int n)
{
switch(n){
case 1:
if(h)
c[0] = c[0] & 0xff | ((u8int)v) << 8;
else
c[0] = c[0] & 0xff00 | (u8int)v;
break;
case 2:
c[0] = v;
break;
case 4:
c[0] = v;
c[1] = v >> 16;
break;
}
}
static u32int
regread(u32int a)
{
u32int v;
switch(a){
case DISPSTAT*2:
v = reg[a/2] & ~7;
if(ppuy >= 160 && ppuy != 227)
v |= 1;
if(hblank)
v |= 2;
if(ppuy == v >> 8)
v |= 4;
return v;
case 0x006:
return ppuy;
case 0x100: case 0x104: case 0x108: case 0x10c:
return timerget((a - 0x100) / 4);
case 0x130:
return keys ^ 0x3ff;
default:
return reg[a/2];
}
}
static void
regwrite16(u32int a, u16int v)
{
u16int *p;
int i;
static u8int ws0[4] = {5,4,3,9};
if(a < 0x56)
ppuwrite(a, v);
else if(a < 0xa0)
sndwrite(a, v);
p = ®[a/2];
switch(a){
case IF*2:
*p &= ~v;
setif(0);
return;
case IME*2: case IE*2:
*p = v;
setif(0);
return;
case DMA0CNTH*2: case DMA1CNTH*2: case DMA2CNTH*2: case DMA3CNTH*2:
i = (a - DMA0CNTH*2) / 12;
if((v & DMAEN) != 0){
if((v >> DMAWHEN & 3) == 0)
dmaact |= 1<<i;
if(i == 3 && (v >> DMAWHEN & 3) == 3)
print("DMA video capture mode\n");
dmar[4*i + DMASRC] = p[-5] | p[-4] << 16;
dmar[4*i + DMADST] = p[-3] | p[-2] << 16;
dmar[4*i + DMACNT] = p[-1];
}else
dmaact &= ~1<<i;
break;
case SOUNDCNTH*2:
soundcnth(v);
break;
case FIFOAH*2: case FIFOBH*2:
fifoput(a >> 2 & 1, p[-1] | v << 16);
break;
case 0x102: case 0x106: case 0x10a: case 0x10e:
timerset((a - 0x102) / 4, v);
break;
case WAITCNT*2:
waitst[3] = waitst[7] = ws0[v & 3];
waitst[0] = ws0[v >> 2 & 3];
waitst[4] = ((v & 1<<4) == 0) + 2;
waitst[1] = ws0[v >> 5 & 3];
waitst[5] = (v & 1<<7) == 0 ? 5 : 2;
waitst[2] = ws0[v >> 8 & 3];
waitst[6] = (v & 1<<10) == 0 ? 9 : 2;
for(i = 0; i < 8; i++)
waitst[8 + i] = waitst[i] + waitst[i | 4];
break;
case 0x301:
cpuhalt = 1;
break;
}
*p = v;
}
static void
regwrite(u32int a, u32int v, int n)
{
u16int w;
switch(n){
case 1:
if((a & ~1) == IF)
w = 0;
else
w = regread(a);
if((a & 1) == 0)
w = w & 0xff00 | (u8int)v;
else
w = w & 0xff | v << 8;
regwrite16(a & ~1, w);
break;
default:
regwrite16(a, v);
break;
case 4:
regwrite16(a, v);
regwrite16(a + 2, v >> 16);
break;
}
}
void
setif(u16int v)
{
reg[IF] |= v;
irq = (reg[IME] & 1) != 0 && (reg[IF] & reg[IE]) != 0;
if(irq)
cpuhalt = 0;
}
u32int
memread(u32int a, int n, int seq)
{
u32int b;
assert((a & n-1) == 0);
switch(a >> 24){
case 0:
b = a & sizeof(bios) - 1;
cyc++;
return arread(bios + b, n);
case 2:
b = a & sizeof(wram1) - 1;
cyc += n > 2 ? 6 : 3;
return arread(wram1 + b, n);
case 3:
b = a & sizeof(wram0) - 1;
cyc++;
return arread(wram0 + b, n);
case 4:
b = a & 0xffffff;
if(b >= sizeof(reg)) goto fault;
cyc++;
if(n == 4)
return regread(b) | regread(b+2) << 16;
else if(n == 1)
if((b & 1) != 0)
return regread(b) >> 8;
else
return regread(b) & 0xff;
return regread(b);
case 5:
b = a & sizeof(pram) - 1;
cyc += (n+1) >> 1;
return ar16read(pram + b/2, b & 1, n);
case 6:
b = a & 128*KB - 1;
if(b >= 64*KB)
b &= ~(32*KB);
cyc += (n+1) >> 1;
return arread(vram + b, n);
case 7:
b = a & sizeof(oam) - 1;
cyc++;
return ar16read(oam + b/2, b & 1, n);
case 8: case 9: case 10: case 11: case 12: case 13:
b = a & 0x1ffffff;
cyc += waitst[(a >> 25) - 4 | seq << 2 | (n > 2) << 3];
if(b >= nrom){
if(b >= eepstart)
return eepromread();
return 0;
}
return arread(rom + b, n);
case 14:
if(backup == SRAM){
b = a & nback - 1;
return arread(back + b, n);
}
if(backup == FLASH)
return flashread(a);
return 0;
default:
fault:
print("read from %#.8ux (pc=%#.8ux)\n", a, curpc);
return 0;
}
}
void
memwrite(u32int a, u32int v, int n)
{
u32int b;
assert((a & n-1) == 0);
switch(a >> 24){
case 0:
return;
case 2:
b = a & sizeof(wram1) - 1;
cyc += n > 2 ? 6 : 3;
arwrite(wram1 + b, v, n);
return;
case 3:
b = a & sizeof(wram0) - 1;
cyc++;
arwrite(wram0 + b, v, n);
return;
case 4:
cyc++;
b = a & 0xffffff;
if(b == 0x410) return;
if(b >= sizeof(reg)) goto fault;
regwrite(b, v, n);
return;
case 5:
b = a & sizeof(pram) - 1;
cyc += (n+1) >> 1;
ar16write(pram + b/2, b & 1, v, n);
return;
case 6:
b = a & 128*KB - 1;
if(b >= 64*KB)
b &= ~(32*KB);
cyc += (n+1) >> 1;
arwrite(vram + b, v, n);
return;
case 7:
b = a & sizeof(oam) - 1;
cyc++;
ar16write(oam + b/2, b & 1, v, n);
return;
case 8: case 9: case 10: case 11: case 12: case 13:
if(backup == EEPROM){
b = a & 0x01ffffff;
if(b >= eepstart)
eepromwrite(v & 1);
}
return;
case 14:
if(backup == SRAM){
b = a & nback - 1;
arwrite(back + b, v, n);
writeback();
return;
}
if(backup == FLASH){
flashwrite(a, v);
return;
}
return;
default:
fault:
print("write to %#.8ux, value %#.8ux (pc=%#.8ux)\n", a, v, curpc);
}
}
void
memreset(void)
{
reg[0x88/2] = 0x200;
reg[BG2PA] = reg[BG2PD] = 0x100;
if(backup == EEPROM)
if(nrom <= 16*KB*KB)
eepstart = 0x1000000;
else
eepstart = 0x1ffff00;
else
eepstart = -1;
}
int
dmastep(void)
{
int i;
u16int *cntp, cnt;
u32int *dr;
u32int v;
int sz, snd;
cyc = 0;
for(i = 0; i < 4; i++)
if((dmaact & 1<<i) != 0)
break;
if(i == 4)
return cyc;
curpc = -1;
cntp = reg + DMA0CNTH + i * 6;
cnt = *cntp;
dr = dmar + 4 * i;
snd = (cnt >> DMAWHEN & 3) == 3 && (i == 1 || i == 2);
if(snd)
cnt = cnt & ~(3 << DMADCNT) | DMAFIX << DMADCNT | DMAWIDE;
sz = (cnt & DMAWIDE) != 0 ? 4 : 2;
if(i == 0)
dr[DMASRC] &= 0x07FFFFFF;
else
dr[DMASRC] &= 0x0FFFFFFF;
if(i != 3)
dr[DMADST] &= 0x7FFFFFFF;
else
dr[DMADST] &= 0x0FFFFFFF;
v = memread(dr[DMASRC] & -sz, sz, 1);
memwrite(dr[DMADST] & -sz, v, sz);
switch(cnt >> DMADCNT & 3){
case DMAINC: case DMAINCREL: dr[DMADST] += sz; break;
case DMADEC: dr[DMADST] -= sz; break;
}
switch(cnt >> DMASCNT & 3){
case DMAINC: dr[DMASRC] += sz; break;
case DMADEC: dr[DMASRC] -= sz; break;
}
if(dr[DMACNT] == 0)
dr[DMACNT] = i != 3 ? 0x4000 : 0x10000;
if(--dr[DMACNT] == 0){
dmaact &= ~(1<<i);
if((cnt & DMAREP) != 0){
dr[DMACNT] = cntp[-1];
if((cnt >> DMADCNT & 3) == DMAINCREL)
dr[DMADST] = cntp[-3] | cntp[-2] << 16;
}else
*cntp &= ~DMAEN;
if((cnt & DMAIRQ) != 0)
setif(IRQDMA0 << i);
}
return cyc;
}
void
dmastart(int cond)
{
int i;
u16int *cntp, cnt, c;
cntp = reg + DMA0CNTH;
for(i = 0; i < 4; i++, cntp += 6){
cnt = *cntp;
if((cnt & DMAEN) == 0)
continue;
c = cnt >> DMAWHEN & 3;
if(c == 3)
c += (i + 1) / 2;
if(c == cond){
dmaact |= 1<<i;
if(c == DMASOUND)
dmar[i * 4 + DMACNT] = 4;
}
}
}
int eepromstate, eeprompos, eepromaddr;
u64int eepromdata;
enum {
EEPROMCMD,
EEPROMRDCMD,
EEPROMRDRESP,
EEPROMWRCMD,
EEPROMWRDATA,
EEPROMWRRESP,
};
static int
eepromread(void)
{
int v;
switch(eepromstate){
case EEPROMRDRESP:
eeprompos++;
if(eeprompos <= 4)
return 0;
if(eeprompos == 68){
eepromstate = EEPROMCMD;
eeprompos = 0;
}
v = eepromdata >> 63;
eepromdata <<= 1;
return v;
case EEPROMWRRESP:
if(++eeprompos == 1000){
eepromstate = EEPROMCMD;
eeprompos = 0;
return 1;
}
return 0;
default:
return 0;
}
}
static void
eepromwrite(int n)
{
uchar *p;
switch(eepromstate){
case EEPROMCMD:
eepromaddr = eepromaddr << 1 | n;
if(++eeprompos >= 2){
switch(eepromaddr & 3){
case 2:
eepromstate = EEPROMWRCMD;
break;
case 3:
eepromstate = EEPROMRDCMD;
break;
}
eeprompos = 0;
}
break;
case EEPROMRDCMD:
case EEPROMWRCMD:
eepromaddr = eepromaddr << 1 | n;
eeprompos++;
if(nback == 512){
if(eeprompos >= 7)
eepromaddr = eepromaddr >> 1 & 0x3f;
else
break;
}else{
if(eeprompos >= 15)
eepromaddr = eepromaddr >> 1 & 0x3fff;
else
break;
}
if(eepromstate == EEPROMRDCMD){
p = back + eepromaddr * 8;
eepromdata = p[0] | p[1] << 8 | p[2] << 16 | p[3] << 24 | (u64int)p[4] << 32 |
(u64int)p[5] << 40 | (u64int)p[6] << 48 | (u64int)p[7] << 56;
eeprompos = 0;
eepromstate = EEPROMRDRESP;
break;
}else{
eepromdata = n;
eeprompos = 1;
eepromstate = EEPROMWRDATA;
break;
}
case EEPROMWRDATA:
if(eeprompos == 64){
p = back + eepromaddr * 8;
p[0] = eepromdata;
p[1] = eepromdata >> 8;
p[2] = eepromdata >> 16;
p[3] = eepromdata >> 24;
p[4] = eepromdata >> 32;
p[5] = eepromdata >> 40;
p[6] = eepromdata >> 48;
p[7] = eepromdata >> 56;
eepromstate = EEPROMWRRESP;
eeprompos = 0;
writeback();
break;
}
eepromdata = eepromdata << 1 | n;
eeprompos++;
break;
}
}
int flashstate, flashmode, flashbank;
enum {
FLASHCMD0,
FLASHCMD1,
FLASHCMD2,
FLASHBANK,
FLASHWRITE,
FLASHID = 1,
FLASHERASE = 2,
};
static u8int
flashread(u16int a)
{
if((flashmode & FLASHID) != 0)
return (a & 1) != 0 ? 0xd4 : 0xbf;
return back[(flashbank << 16) + a];
}
static void
flashwrite(u16int a, u8int v)
{
int erase;
switch(flashstate){
case FLASHCMD0:
if(a == 0x5555 && v == 0xaa)
flashstate = FLASHCMD1;
break;
case FLASHCMD1:
if(a == 0x2aaa && v == 0x55)
flashstate = FLASHCMD2;
else
flashstate = FLASHCMD0;
break;
case FLASHCMD2:
flashstate = FLASHCMD0;
erase = flashmode & FLASHERASE;
flashmode &= ~FLASHERASE;
switch(v){
case 0x90: flashmode |= FLASHID; break;
case 0xF0: flashmode &= ~FLASHID; break;
case 0x80: flashmode |= FLASHERASE; break;
case 0x10:
if(erase){
memset(back, 0xff, nback);
writeback();
}
break;
case 0x30:
if(erase){
memset(back + (a & 0xf000) + (flashbank << 16), 0xff, 4096);
writeback();
}
break;
case 0xA0:
writeback();
flashstate = FLASHWRITE;
break;
case 0xB0: flashstate = FLASHBANK; break;
default:
print("unknown flash cmd %x\n", v);
}
break;
case FLASHBANK:
flashbank = v % (nback >> 16);
flashstate = FLASHCMD0;
break;
case FLASHWRITE:
back[(flashbank << 16) + a] &= v;
writeback();
flashstate = FLASHCMD0;
break;
}
}