diff --git a/src/core/cpu.zig b/src/core/cpu.zig index a2b726b..fbde5ab 100644 --- a/src/core/cpu.zig +++ b/src/core/cpu.zig @@ -428,22 +428,24 @@ pub const Arm7tdmi = struct { } pub fn step(self: *Self) void { - if (self.cpsr.t.read()) blk: { - const opcode = @truncate(u16, self.pipe.step(self, u16) orelse break :blk); + defer { + if (!self.pipe.flushed) self.r[15] += if (self.cpsr.t.read()) 2 else @as(u32, 4); + self.pipe.flushed = false; + } + + if (self.cpsr.t.read()) { + const opcode = @truncate(u16, self.pipe.step(self, u16) orelse return); if (self.logger) |*trace| trace.mgbaLog(self, opcode); thumb.lut[thumb.idx(opcode)](self, self.bus, opcode); - } else blk: { - const opcode = self.pipe.step(self, u32) orelse break :blk; + } else { + const opcode = self.pipe.step(self, u32) orelse return; if (self.logger) |*trace| trace.mgbaLog(self, opcode); if (checkCond(self.cpsr, @truncate(u4, opcode >> 28))) { arm.lut[arm.idx(opcode)](self, self.bus, opcode); } } - - if (!self.pipe.flushed) self.r[15] += if (self.cpsr.t.read()) 2 else @as(u32, 4); - self.pipe.flushed = false; } pub fn stepDmaTransfer(self: *Self) bool { @@ -481,8 +483,8 @@ pub const Arm7tdmi = struct { // Return if IME is disabled, CPSR I is set or there is nothing to handle if (!self.bus.io.ime or self.cpsr.i.read() or should_handle == 0) return; - // If pipeline isn't full, return but reschedule the handling of the event - if (!self.pipe.isFull()) return; + // If Pipeline isn't full, we have a bug + std.debug.assert(self.pipe.isFull()); // log.debug("Handling Interrupt!", .{}); self.bus.io.haltcnt = .Execute; @@ -501,23 +503,18 @@ pub const Arm7tdmi = struct { self.pipe.reload(self); } - inline fn fetch(self: *Self, comptime T: type) T { + inline fn fetch(self: *Self, comptime T: type, address: u32) T { comptime std.debug.assert(T == u32 or T == u16); // Opcode may be 32-bit (ARM) or 16-bit (THUMB) - defer self.r[15] += if (T == u32) 4 else 2; - // FIXME: You better hope this is optimized out + // Bus.read will advance the scheduler. There are different timings for CPU fetches, + // so we want to undo what Bus.read will apply. We can do this by caching the current tick + // This is very dumb. + // + // FIXME: Please rework this const tick_cache = self.sched.tick; - defer self.sched.tick = tick_cache + Bus.fetch_timings[@boolToInt(T == u32)][@truncate(u4, self.r[15] >> 24)]; + defer self.sched.tick = tick_cache + Bus.fetch_timings[@boolToInt(T == u32)][@truncate(u4, address >> 24)]; - return self.bus.read(T, self.r[15]); - } - - fn debug_log(self: *const Self, file: *const File, opcode: u32) void { - if (self.binary_log) { - self.skyLog(file) catch unreachable; - } else { - self.mgbaLog(file, opcode) catch unreachable; - } + return self.bus.read(T, address); } pub fn panic(self: *const Self, comptime format: []const u8, args: anytype) noreturn { @@ -655,15 +652,6 @@ const Pipeline = struct { }; } - pub fn flush(self: *Self) void { - for (self.stage) |*opcode| opcode.* = null; - self.flushed = true; - - // Note: If using this, add - // if (!self.pipe.flushed) self.r[15] += if (self.cpsr.t.read()) 2 else @as(u32, 4); - // to the end of Arm7tdmi.step - } - pub fn isFull(self: *const Self) bool { return self.stage[0] != null and self.stage[1] != null; } @@ -672,22 +660,22 @@ const Pipeline = struct { comptime std.debug.assert(T == u32 or T == u16); // FIXME: https://github.com/ziglang/zig/issues/12642 - const opcode = self.stage[0..1][0]; + var opcode = self.stage[0]; self.stage[0] = self.stage[1]; - self.stage[1] = cpu.bus.read(T, cpu.r[15]); + self.stage[1] = cpu.fetch(T, cpu.r[15]); return opcode; } pub fn reload(self: *Self, cpu: *Arm7tdmi) void { if (cpu.cpsr.t.read()) { - self.stage[0] = cpu.bus.read(u16, cpu.r[15]); - self.stage[1] = cpu.bus.read(u16, cpu.r[15] + 2); + self.stage[0] = cpu.fetch(u16, cpu.r[15]); + self.stage[1] = cpu.fetch(u16, cpu.r[15] + 2); cpu.r[15] += 4; } else { - self.stage[0] = cpu.bus.read(u32, cpu.r[15]); - self.stage[1] = cpu.bus.read(u32, cpu.r[15] + 4); + self.stage[0] = cpu.fetch(u32, cpu.r[15]); + self.stage[1] = cpu.fetch(u32, cpu.r[15] + 4); cpu.r[15] += 8; } diff --git a/src/core/cpu/thumb/alu.zig b/src/core/cpu/thumb/alu.zig index a05b26b..c47e63c 100644 --- a/src/core/cpu/thumb/alu.zig +++ b/src/core/cpu/thumb/alu.zig @@ -73,8 +73,6 @@ pub fn fmt4(comptime op: u4) InstrFn { cpu.cpsr.z.write(result == 0); cpu.cpsr.c.write(overflow); cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1); - - // FIXME: Pretty sure CMN Is the same }, 0x6 => { // SBC