diff options
Diffstat (limited to 'src/cpu.adb')
| -rw-r--r-- | src/cpu.adb | 68 |
1 files changed, 26 insertions, 42 deletions
diff --git a/src/cpu.adb b/src/cpu.adb index 809e039..6ea3f5d 100644 --- a/src/cpu.adb +++ b/src/cpu.adb @@ -1,5 +1,4 @@ with Ada.Sequential_IO; -with Ada.Text_IO; with Bit_Ops; package body CPU is @@ -52,47 +51,32 @@ package body CPU is end Skip; procedure Math (Inst : in out Instance; VX, VY : Register_Index; N : Byte) - is begin - case N is - when 0 => - Inst.Registers (VX) := Inst.Registers (VY); - when 1 => - Inst.Registers (VX) := Bit_Ops.Bitwise_Or - (Inst.Registers (VX), Inst.Registers (VY)); - when 2 => - Inst.Registers (VX) := Bit_Ops.Bitwise_And - (Inst.Registers (VX), Inst.Registers (VY)); - when 3 => - Inst.Registers (VX) := Bit_Ops.Bitwise_Xor - (Inst.Registers (VX), Inst.Registers (VY)); - when 4 => - declare - X : constant Byte := Inst.Registers (VX); - Y : constant Byte := Inst.Registers (VY); - begin - Inst.Registers (VX) := X + Y; - Inst.Registers (15) := - (if Integer (X) + Integer (Y) > Integer (X + Y) - then 1 else 0); - end; - when 5 => - declare - X : constant Byte := Inst.Registers (VX); - Y : constant Byte := Inst.Registers (VY); - begin - Inst.Registers (VX) := X - Y; - Inst.Registers (15) := (if X >= Y then 1 else 0); - end; - when 6 => - Inst.Registers (15) := Inst.Registers (VX) mod 2; - Inst.Registers (VX) := Inst.Registers (VX) / 2; - when 14 => - Inst.Registers (15) := Inst.Registers (VX) / (2 ** 7); - Inst.Registers (VX) := Inst.Registers (VX) * 2; - when others => begin - Ada.Text_IO.Put_Line ("Uh oh!"); - Ada.Text_IO.Put_Line (Byte'Image (N)); - end; + is + X : constant Byte := Inst.Registers (VX); + Y : constant Byte := Inst.Registers (VY); + begin + case Math_Class'Enum_Val (N) is + when Assign => Inst.Registers (VX) := Y; + when Bit_Or => Inst.Registers (VX) := Bit_Ops.Bitwise_Or (X, Y); + when Bit_And => Inst.Registers (VX) := Bit_Ops.Bitwise_And (X, Y); + when Bit_Xor => Inst.Registers (VX) := Bit_Ops.Bitwise_Xor (X, Y); + when Add => + Inst.Registers (VX) := X + Y; + Inst.Registers (15) := + (if Integer (X) + Integer (Y) > Integer (X + Y) + then 1 else 0); + when Sub_Y => + Inst.Registers (VX) := X - Y; + Inst.Registers (15) := (if X >= Y then 1 else 0); + when Shift_Right => + Inst.Registers (15) := X mod 2; + Inst.Registers (VX) := X / 2; + when Sub_X => + Inst.Registers (VX) := Y - X; + Inst.Registers (15) := (if Y >= X then 1 else 0); + when Shift_Left => + Inst.Registers (15) := X / (2 ** 7); + Inst.Registers (VX) := X * 2; end case; end Math; |