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Grayscale, timing fixes.

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This commit is contained in:
Andrea Orrù 2014-02-18 17:44:29 +01:00
parent 483361cec2
commit 67a5791fcc
1 changed files with 59 additions and 48 deletions
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107
src/ppu.cpp
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@ -27,30 +27,36 @@ u8 atShiftL, atShiftH; u16 bgShiftL, bgShiftH;
bool atLatchL, atLatchH;
// Rendering counters:
int scanline, cycle;
int scanline, dot;
bool frameOdd;
inline bool rendering() { return mask.bg || mask.spr; }
inline int spr_height() { return ctrl.sprSz ? 16 : 8; }
/* Access PPU memory */
template <bool wr> u8 mem_access(u16 addr, u8 v = 0)
u8 rd(u16 addr)
{
u8* ref;
switch (addr)
{
case 0x0000 ... 0x1FFF: return Cartridge::chr_access<wr>(addr, v); // CHR-ROM/RAM.
case 0x2000 ... 0x3EFF: ref = &ciRam[addr - 0x2000]; break; // Nametables.
case 0x0000 ... 0x1FFF: return Cartridge::chr_access<0>(addr); // CHR-ROM/RAM.
case 0x2000 ... 0x3EFF: return ciRam[addr - 0x2000]; // Nametables.
case 0x3F00 ... 0x3FFF: // Palettes:
if ((addr & 0x13) == 0x10) addr &= ~0x10;
ref = &cgRam[addr & 0x1F];
break;
return cgRam[addr & 0x1F] & (mask.gray ? 0x30 : 0xFF);
default: return 0;
}
}
void wr(u16 addr, u8 v)
{
switch (addr)
{
case 0x0000 ... 0x1FFF: Cartridge::chr_access<1>(addr, v); break; // CHR-ROM/RAM.
case 0x2000 ... 0x3EFF: ciRam[addr - 0x2000] = v; break; // Nametables.
case 0x3F00 ... 0x3FFF: // Palettes:
if ((addr & 0x13) == 0x10) addr &= ~0x10;
cgRam[addr & 0x1F] = v; break;
}
if (wr) return *ref = v;
else return *ref;
}
inline u8 rd(u16 addr) { return mem_access<0>(addr); }
inline u8 wr(u16 addr, u8 v) { return mem_access<1>(addr, v); }
/* Access PPU through registers. */
template <bool write> u8 access(u16 index, u8 v)
@ -199,39 +205,44 @@ void load_sprites()
/* Process a pixel, draw it if it's on screen */
void pixel()
{
u8 palette, objPalette = 0;
u8 palette = 0, objPalette = 0;
bool objPriority = 0;
int x = dot - 2;
if (scanline < 240 and cycle >= 1 and cycle <= 256)
if (scanline < 240 and x >= 0 and x < 256)
{
// Background:
palette = (NTH_BIT(bgShiftH, 15 - fX) << 1) |
NTH_BIT(bgShiftL, 15 - fX);
if (palette)
palette |= ((NTH_BIT(atShiftH, 7 - fX) << 1) |
NTH_BIT(atShiftL, 7 - fX)) << 2;
if (mask.bg and not (!mask.bgLeft && x < 8))
{
// Background:
palette = (NTH_BIT(bgShiftH, 15 - fX) << 1) |
NTH_BIT(bgShiftL, 15 - fX);
if (palette)
palette |= ((NTH_BIT(atShiftH, 7 - fX) << 1) |
NTH_BIT(atShiftL, 7 - fX)) << 2;
}
// Sprites:
for (int i = 7; i >= 0; i--)
{
if (oam[i].id == 64) continue; // Void entry.
if (mask.spr and not (!mask.sprLeft && x < 8))
for (int i = 7; i >= 0; i--)
{
if (oam[i].id == 64) continue; // Void entry.
unsigned sprX = cycle - oam[i].x;
if (sprX >= 8) continue;
if (oam[i].attr & 0x40) sprX ^= 7; // Horizontal flip.
unsigned sprX = x - oam[i].x;
if (sprX >= 8) continue;
if (oam[i].attr & 0x40) sprX ^= 7; // Horizontal flip.
u8 sprPalette = (NTH_BIT(oam[i].dataH, 7 - sprX) << 1) |
NTH_BIT(oam[i].dataL, 7 - sprX);
if (sprPalette == 0) continue;
u8 sprPalette = (NTH_BIT(oam[i].dataH, 7 - sprX) << 1) |
NTH_BIT(oam[i].dataL, 7 - sprX);
if (sprPalette == 0) continue;
if (oam[i].id == 0 && palette && cycle != 255) status.sprHit = true;
sprPalette |= (oam[i].attr & 3) << 2;
objPalette = sprPalette + 16;
objPriority = oam[i].attr & 0x20;
}
if (oam[i].id == 0 && palette && x != 255) status.sprHit = true;
sprPalette |= (oam[i].attr & 3) << 2;
objPalette = sprPalette + 16;
objPriority = oam[i].attr & 0x20;
}
if (objPalette && (palette == 0 || objPriority == 0)) palette = objPalette;
IO::draw_pixel(cycle - 1, scanline, nesRgb[rd(0x3F00 + (rendering() ? palette : 0))]);
IO::draw_pixel(x, scanline, nesRgb[rd(0x3F00 + (rendering() ? palette : 0))]);
}
bgShiftL <<= 1; bgShiftH <<= 1;
@ -244,22 +255,23 @@ template<Scanline s> void scanline_cycle()
{
static u16 addr;
if (s == NMI and cycle == 1) { status.vBlank = true; if (ctrl.nmi) CPU::set_nmi(); }
else if (s == POST and cycle == 0) IO::flush_screen();
if (s == NMI and dot == 1) { status.vBlank = true; if (ctrl.nmi) CPU::set_nmi(); }
else if (s == POST and dot == 0) IO::flush_screen();
else if (s == VISIBLE or s == PRE)
{
// Sprites:
switch (cycle)
switch (dot)
{
case 1: clear_oam(); if (s == PRE) { status.sprOvf = status.sprHit = false; } break;
case 257: eval_sprites(); break;
case 321: load_sprites(); break;
}
// Background:
switch (cycle)
switch (dot)
{
case 2 ... 255: case 322 ... 337:
switch (cycle % 8)
pixel();
switch (dot % 8)
{
// Nametable:
case 1: addr = nt_addr(); reload_shift(); break;
@ -274,18 +286,17 @@ template<Scanline s> void scanline_cycle()
// Background (high bits):
case 7: addr += 8; break;
case 0: bgH = rd(addr); h_scroll();
}
pixel(); break;
case 256: bgH = rd(addr); v_scroll(); pixel(); break; // Vertical bump.
case 257: reload_shift(); h_update(); break; // Update horizontal position.
case 280 ... 304: if (s == PRE) v_update(); break; // Update vertical position.
} break;
case 256: pixel(); bgH = rd(addr); v_scroll(); break; // Vertical bump.
case 257: pixel(); reload_shift(); h_update(); break; // Update horizontal position.
case 280 ... 304: if (s == PRE) v_update(); break; // Update vertical position.
// No shift reloading:
case 1: addr = nt_addr(); if (s == PRE) status.vBlank = false; break;
case 321: case 339: addr = nt_addr(); break;
// Nametable fetch instead of attribute:
case 338: nt = rd(addr); break;
case 340: nt = rd(addr); if (s == PRE && rendering() && frameOdd) cycle++;
case 340: nt = rd(addr); if (s == PRE && rendering() && frameOdd) dot++;
}
}
}
@ -300,10 +311,10 @@ void step()
case 241: scanline_cycle<NMI>(); break;
case 261: scanline_cycle<PRE>(); break;
}
// Update cycle and scanline counters:
if (++cycle > 340)
// Update dot and scanline counters:
if (++dot > 340)
{
cycle %= 341;
dot %= 341;
if (++scanline > 261)
{
scanline = 0;