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package ISA is
type Byte is mod 2 ** 8;
type Address is mod 2 ** 12;
type Register_Index is mod 2 ** 4;
type Bank is array (Address) of Byte;
type Register_Bank is array (Register_Index) of Byte;
type Pixel is array (0 .. Byte'Size - 1) of Boolean;
pragma Pack (Pixel);
type Opcode_Value is mod 2 ** 12;
type Opcode_Raw is mod 2 ** 16;
type Opcode_Class is (
Flow, Jump, Call, Equal, Not_Equal, Compare, Set_Register, Add, Math,
Not_Compare, Set_Address, Jump_Relative, Random, Draw_Sprite, Input, Misc
) with Size => 4;
type Opcode is record
Value : Opcode_Value;
Class : Opcode_Class;
end record with
Size => Opcode_Raw'Size;
for Opcode use record
Value at 0 range 0 .. 11;
Class at 0 range 12 .. 15;
end record;
for Opcode_Class use (
Flow => 0,
Jump => 1,
Call => 2,
Equal => 3,
Not_Equal => 4,
Compare => 5,
Set_Register => 6,
Add => 7,
Math => 8,
Not_Compare => 9,
Set_Address => 10,
Jump_Relative => 11,
Random => 12,
Draw_Sprite => 13,
Input => 14,
Misc => 15
);
type Flow_Class is (
Scroll_Down_0, Scroll_Down_1, Scroll_Down_2, Scroll_Down_3,
Scroll_Down_4, Scroll_Down_5, Scroll_Down_6, Scroll_Down_7,
Scroll_Down_8, Scroll_Down_9, Scroll_Down_10, Scroll_Down_11,
Scroll_Down_12, Scroll_Down_13, Scroll_Down_14, Scroll_Down_15,
Clear_Screen, Ret, Scroll_Right, Scroll_Left, Exit_Interpreter, Low_Res,
High_Res
);
for Flow_Class use (
Scroll_Down_0 => 16#C0#,
Scroll_Down_1 => 16#C1#,
Scroll_Down_2 => 16#C2#,
Scroll_Down_3 => 16#C3#,
Scroll_Down_4 => 16#C4#,
Scroll_Down_5 => 16#C5#,
Scroll_Down_6 => 16#C6#,
Scroll_Down_7 => 16#C7#,
Scroll_Down_8 => 16#C8#,
Scroll_Down_9 => 16#C9#,
Scroll_Down_10 => 16#CA#,
Scroll_Down_11 => 16#CB#,
Scroll_Down_12 => 16#CC#,
Scroll_Down_13 => 16#CD#,
Scroll_Down_14 => 16#CE#,
Scroll_Down_15 => 16#CF#,
Clear_Screen => 16#E0#,
Ret => 16#EE#,
Scroll_Right => 16#FB#,
Scroll_Left => 16#FC#,
Exit_Interpreter => 16#FD#,
Low_Res => 16#FE#,
High_Res => 16#FF#
);
type Math_Class is (
Assign, Bit_Or, Bit_And, Bit_Xor, Add, Sub_Y, Shift_Right, Sub_X,
Shift_Left
);
for Math_Class use (
Assign => 0,
Bit_Or => 1,
Bit_And => 2,
Bit_Xor => 3,
Add => 4,
Sub_Y => 5,
Shift_Right => 6,
Sub_X => 7,
Shift_Left => 14
);
type Input_Class is (Key_Down, Key_Up);
for Input_Class use (
Key_Down => 16#9E#,
Key_Up => 16#A1#
);
type Misc_Class is (
Get_Delay, Get_Key, Set_Delay, Set_Sound, Add_Address, Get_Font,
Get_Font_10, Get_BCD, Reg_Store, Reg_Load, Reg_Store_X, Reg_Load_X
);
for Misc_Class use (
Get_Delay => Opcode_Value (16#07#),
Get_Key => Opcode_Value (16#0A#),
Set_Delay => Opcode_Value (16#15#),
Set_Sound => Opcode_Value (16#18#),
Add_Address => Opcode_Value (16#1E#),
Get_Font => Opcode_Value (16#29#),
Get_Font_10 => Opcode_Value (16#30#),
Get_BCD => Opcode_Value (16#33#),
Reg_Store => Opcode_Value (16#55#),
Reg_Load => Opcode_Value (16#65#),
Reg_Store_X => Opcode_Value (16#75#),
Reg_Load_X => Opcode_Value (16#85#)
);
Start_Address : constant Address := 16#200#;
function To_Byte (O : Opcode) return Byte;
function X_Register (O : Opcode) return Register_Index;
function Y_Register (O : Opcode) return Register_Index;
end ISA;
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