A cross-platform simulator for the GreenArrays GA144 multi-computer chip.
Simplify slot execution logic
I can probably just do a for (0..3) loop here rather than a labeled
switch.
+29
-15
+29
-15
src/f18.zig
+29
-15
src/f18.zig
···
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11
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12
/// Within RAM or ROM, an address is incremented after each word is fetched,
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/// circularly within whichever storage class it currently points to. Within I/O
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-
/// space, it is not incremented.
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+
/// space, it is not incremented. Incrementing never affects bits P8 or P9
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pub fn increment(self: *ProgramCounter) void {
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if (!self.address.io) self.address.local +%= 1;
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}
···
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slot_2: Opcode,
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slot_1: Opcode,
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slot_0: Opcode,
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+
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pub fn getSlot(self: Instruction, slot: u2) Opcode {
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return switch (slot) {
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0 => self.slot_0,
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1 => self.slot_1,
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2 => self.slot_2,
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3 => Opcode.fromInt(self.slot_3),
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};
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}
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};
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/// An F18A computer
···
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self.slot = 0;
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self.state = .execution;
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current_slot: switch (self.slot) {
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-
0 => {
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_ = self.execute(instruction.slot_0);
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if (self.state != .execution) continue :current_state self.state;
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continue :current_slot self.slot;
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},
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1 => {
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_ = self.execute(instruction.slot_1);
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if (self.state != .execution) continue :current_state self.state;
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continue :current_slot self.slot;
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},
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2 => {
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_ = self.execute(instruction.slot_2);
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+
0...2 => {
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_ = self.execute(instruction.getSlot(self.slot));
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if (self.state != .execution) continue :current_state self.state;
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continue :current_slot self.slot;
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},
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3 => {
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_ = self.execute(Opcode.fromInt(instruction.slot_3));
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if (self.state != .execution) continue :current_state self.state;
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return;
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break :current_state;
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},
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}
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continue :current_state self.state;
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return;
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},
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.unext => {
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const r = self.return_stack.t;
···
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const short_jump: ShortJump = .{ .destination = 0b101 };
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try expectEqual(word, @as(Word, @bitCast(short_jump)));
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}
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+
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test Instruction {
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const instruction: Instruction = .{
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.slot_0 = .@"@p",
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.slot_1 = .@";",
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.slot_2 = .@";",
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.slot_3 = 1,
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};
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+
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try expectEqual(0b010000000000000001, @as(Word, @bitCast(instruction)));
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try expectEqual(instruction.getSlot(0), instruction.slot_0);
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try expectEqual(instruction.getSlot(1), instruction.slot_1);
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try expectEqual(instruction.getSlot(2), instruction.slot_2);
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try expectEqual(instruction.getSlot(3), .unext);
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}
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test "computer is initialized" {