diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mos6502.rs | 33 | ||||
| -rw-r--r-- | src/ppu.rs | 21 |
2 files changed, 30 insertions, 24 deletions
diff --git a/src/mos6502.rs b/src/mos6502.rs index fdce0ab..e95910f 100644 --- a/src/mos6502.rs +++ b/src/mos6502.rs @@ -232,6 +232,13 @@ macro_rules! read16 { $mem.read($laddr))); } +macro_rules! read16wrap { + ($mem: expr, $laddr: expr) => ({ + let naddr = ($laddr & 0xff00) | (($laddr as u8).wrapping_add(1) as u16); + make16!($mem.read(naddr), $mem.read($laddr)) + }); +} + mod ops { use memory::VMem; use mos6502::*; @@ -392,13 +399,13 @@ mod ops { fn rol(cpu: &mut CPU) { let res = match cpu.acc { true => { - let t = (cpu.a as u16) << 1; - cpu.a = t as u8 | cpu.get_carry(); + let t = ((cpu.a as u16) << 1) | (cpu.get_carry() as u16); + cpu.a = t as u8; t }, false => { - let t = (cpu.mem.read(cpu.ea) as u16) << 1; - cpu.mem.write(cpu.ea, t as u8 | cpu.get_carry()); + let t = ((cpu.mem.read(cpu.ea) as u16) << 1) | (cpu.get_carry() as u16); + cpu.mem.write(cpu.ea, t as u8); t }}; let mut status = cpu.status & !(CARRY_FLAG | ZERO_FLAG | NEG_FLAG); @@ -413,15 +420,15 @@ mod ops { let res = match cpu.acc { true => { let old = cpu.a; - let t = old >> 1; - cpu.a = t as u8 | (cpu.get_carry() << 7); + let t = (old >> 1) | (cpu.get_carry() << 7); + cpu.a = t as u8; status |= (old & 1) as u8; /* carry flag */ t }, false => { let old = cpu.mem.read(cpu.ea); - let t = old >> 1; - cpu.mem.write(cpu.ea, t as u8 | (cpu.get_carry() << 7)); + let t = (old >> 1) | (cpu.get_carry() << 7); + cpu.mem.write(cpu.ea, t as u8); status |= (old & 1) as u8; /* carry flag */ t }}; @@ -649,17 +656,17 @@ mod addr { fn ind(cpu: &mut CPU) -> u8 { let addr = read16!(cpu.mem, cpu.opr); - cpu.ea = read16!(cpu.mem, addr); 0 + cpu.ea = read16wrap!(cpu.mem, addr); 0 } fn xin(cpu: &mut CPU) -> u8 { - cpu.ea = read16!(cpu.mem, + cpu.ea = read16wrap!(cpu.mem, cpu.mem.read(cpu.opr) .wrapping_add(cpu.x) as u16) as u16; 0 } fn iny(cpu: &mut CPU) -> u8 { - let base = read16!(cpu.mem, cpu.mem.read(cpu.opr) as u16); + let base = read16wrap!(cpu.mem, cpu.mem.read(cpu.opr) as u16); let sum = (base & 0xff) + (cpu.y as u16); cpu.ea = (base & 0xff00).wrapping_add(sum); (sum >> 8) as u8 /* boundary cross if carry */ @@ -747,7 +754,7 @@ impl<'a> CPU<'a> { } else { let pc = self.pc; let opcode = self.mem.read(pc) as usize; - /* + /* let len = INST_LENGTH[opcode]; let mut code = vec![0; len as usize]; for i in 0..len as u16 { @@ -756,7 +763,7 @@ impl<'a> CPU<'a> { println!("0x{:04x} {} a:{:02x} x:{:02x} y:{:02x} s: {:02x} sp: {:02x}", pc, disasm::parse(opcode as u8, &code[1..]), self.a, self.x, self.y, self.status, self.sp); - */ + */ /* update opr pointing to operands of current inst */ self.opr = pc.wrapping_add(1); /* update program counter pointing to next inst */ @@ -447,7 +447,7 @@ impl<'a> PPU<'a> { let ppustatus = 0xa0; let oamaddr = 0x00; let buffered_read = 0x00; - let cycle = 370; + let cycle = 340; let scanline = 240; PPU { scanline, @@ -478,7 +478,7 @@ impl<'a> PPU<'a> { self.ppustatus = self.ppustatus & 0x80; self.w = false; self.buffered_read = 0x00; - self.cycle = 370; + self.cycle = 340; self.scanline = 240; } @@ -528,18 +528,11 @@ impl<'a> PPU<'a> { self.reset_cx(); self.fetch_sprite(); } - if pre_line { - if cycle == 1 { - /* clear vblank, sprite zero hit & overflow */ - self.ppustatus &= !(PPU::FLAG_VBLANK | - PPU::FLAG_SPRITE_ZERO | PPU::FLAG_OVERFLOW); - self.bg_pixel = 0 - } else if cycle == 339 && self.f { + if pre_line && cycle == 339 && self.f { self.scanline = 0; self.cycle = 0; self.f = !self.f; return false; - } } } } else { @@ -549,11 +542,17 @@ impl<'a> PPU<'a> { self.ppustatus |= PPU::FLAG_VBLANK; } self.scr.render(); - self.cycle += 1; + self.cycle = 2; self.early_read = false; return !self.early_read && self.get_flag_nmi(); /* trigger cpu's NMI */ } } + if pre_line && cycle == 1 { + /* clear vblank, sprite zero hit & overflow */ + self.ppustatus &= !(PPU::FLAG_VBLANK | + PPU::FLAG_SPRITE_ZERO | PPU::FLAG_OVERFLOW); + self.bg_pixel = 0; + } self.cycle += 1; if self.cycle > 340 { self.cycle = 0; |