Standardize Transient bytecode

[redtechtiger]

This is important because it will allow for changes to be made more swiftly to the project.

[redtechtiger]

Current standard:

Each instruction is 8 bytes (64 bits) long, following this layout:	Byte	0	1	2	3	4	5	6	7
Purpose	Opcode	Size	Source1 High	Source1 Low	Source2 High	Source2 Low	Destination High	Destination Low

Instructions are expected to begin at offset 0x00 (beginning of file) and to be aligned to a multiple of 8. The program counter increments by 8 after executing an instruction successfully. The last instruction is to be a halt, and following this, all variable storage is to be placed. source1, source2, and destination are addresses that point to the base address of each variable. Size is the amount of bytes to be read, starting with the base pointer.

[redtechtiger]

Revision 1:

Default endianness is now little-endian, to allow for variables to be downcasted. Instructions are no longer fixed-length but instead depend on the instructions. The pointer size (word size) is now 32 bits. The length of memory instructions should be dynamic and there are to be flags specifying the execution mode.

Layout:	Byte	0	1	2	..
Purpose	Opcode	Pointer mode	Address size	Instruction-specific data ..

Pointer mode: Each argument is assigned two bits, meaning that each instruction can have a maximum of four arguments. The first argument (leftmost) corresponds to bits 0 and 1 of the pointer mode field. These can be three values: 0: absolute addresses 1: pointer-to-pointer 2: immediate

Address size: Describes the length of data to be read at each one of the pointers. This is redundant if the pointer mode is pointer-to-pointer or immediate, as the pointer size is always 32 bits. Being an 8-bit (1 byte) field, this gives 2 bits per argument, i.e. three values: 0: 16 bit value 1: 32 bit value 2: 64 bit value

[redtechtiger]

Possible instructions:

//                    Value Value Sum
add ptr_mode add_size arg_1 arg_2 arg_3
//                    Ptr   Value
jie ptr_mode add_size arg_1 arg_2
//
hlt

[redtechtiger]

Planned 0.2.0 instruction set

Mov Layout: opcode ptr_mode add_size arg_1 arg_2 Opcode: 0x01 Description: Sets arg_1 to arg_2

Add Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x02 Description: Adds arg_1 and arg_2 and stores in arg_3

Sub Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x03 Description: Subtracts arg_2 from arg_1 and stores in arg_3

Mul Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x04 Description: Multiplies arg_1 and arg_2 and stores in arg_3

Div Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x05 Description: Divides arg_1 by arg_2 and stores quotient in arg_3

Rem Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x06 Description: Divides arg_1 and arg_2 and stores remainder in arg_3

Equ Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x07 Description: If arg_1 is equal to arg_2, store 0x1 in arg_3, otherwise store 0x0

Cgt Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x08 Description: If arg_1 is greater than arg_2, store 0x1 in arg_3, otherwise store 0x0

Clt Layout: opcode ptr_mode add_size arg_1 arg_2 arg_3 Opcode: 0x09 Description: If arg_1 is less than arg_2, store 0x1 in arg_3, otherwise store 0x0

Jmp Layout: opcode ptr_mode arg_1 Opcode: 0x0A Description: Set program counter to arg_1, effectively jumping to arg_1

Jie Layout: opcode ptr_mode add_size arg_1 arg_2 Opcode: 0x0B Description: Set program counter to arg_2 if arg_1 is 0x1.

Jne Layout: opcode ptr_mode add_size arg_1 arg_2 Opcode: 0x0C Description: Set program counter to arg_2 if arg_1 is 0x0.

PutI Layout: opcode ptr_mode add_size arg_1 Opcode: 0x0D Description: Print arg_1 to the console as an integer.

PutC Layout: opcode ptr_mode add_size arg_1 Opcode: 0x0E Description: Print arg_1 to the console as an ascii character.

Imz Layout: opcode ptr_mode add_size arg_1 Opcode: 0x0F Description: Invokes the image size (in bytes) from the virtual machine and stores it in arg_1

Hlt Layout: opcode Opcode: 0xFF Description: Halts execution and exits the virtual machine