Opcode Reference

Sizes are in bytes, opcode included. S is the operand stack, top on the right.

Stack and variables

Opcode	Mnemonic	Size	Effect
`0x02`	`POP v`	2	Pop a value into variable slot `v`.
`0x03`	`PUSH tag x`	3	Push a value, see PUSH type tags.
`0xA6`	`INC`	1	Add 1 to the top of the stack.
`0xA7`	`DEC`	1	Subtract 1 from the top of the stack.
`0xA8`	`INCV v`	2	Increment variable slot `v`.
`0xA9`	`DECV v`	2	Decrement variable slot `v`.
`0xAB`	`CPY v`	2	Copy the top of the stack into variable slot `v` without popping it (used for the `repeat` iterator).
`0xDE`	`DEREF`	1	Pop a slot number and push that variable’s value (`*r`). Stops the VM if the slot does not exist.

Tag	Operand
`0x01`	string pool index
`0x02`	integer constant pool index
`0x03`	variable slot to read
`0x04`	immediate integer (references, `JOIN` count)
`0x05`	float constant pool index

All pop two values and push one. Integer operands give an integer; a float operand gives a float. A string operand is a runtime error.

Opcode	Mnemonic	Effect
`0xA0`	`ADD`	`a + b`
`0xA1`	`SUB`	`a - b`
`0xA2`	`MUL`	`a * b`
`0xA3`	`DIV`	`a / b` (always floating point)
`0xA4`	`POW`	`a ^ b`
`0xA5`	`MOD`	`a % b` (integer `% 0` is a runtime error)
`0xAA`	`JOIN`	Pop a count `n`, then join the next `n` values into one string (`..`).

Opcode	Mnemonic	Size	Effect
`0xDA`	`ARRWRITE a`	2	Stack `[value, index]`: store `value` in array `a`, creating or growing it.
`0xDB`	`ARRREAD a`	2	Stack `[index]`: push element `index` of array `a`.

Errors: negative write index, missing array, index out of range.

The current compiler emits only the 32-bit forms (opcode + 4-byte address, 5 bytes). The 8-bit forms (2 bytes) are kept so older programs still run.

8-bit	32-bit	Mnemonic	Effect
`0x05`	`0x06`	`JUMP`	Unconditional jump.
`0x01`	`0x07`	`CALL`	Push a frame and jump to a routine.
`0xB0`	`0xC0`	`JEQ`	Pop `b`, `a`; jump if `a == b`.
`0xB1`	`0xC1`	`JGR`	jump if `a > b`
`0xB2`	`0xC2`	`JLS`	jump if `a < b`
`0xB3`	`0xC3`	`JGE`	jump if `a >= b`
`0xB4`	`0xC4`	`JLE`	jump if `a <= b`
`0xB5`	`0xC5`	`JNE`	jump if `a != b`

Two strings compare lexicographically, other values numerically. Jump targets inside a routine are relative to the routine’s start.

Opcode	Mnemonic	Size	Effect
`0x04`	`EXEC f`	2	Call built-in function `f`, see Built-in Functions.
`0xFE`	`RET`	1	Return from a routine.
`0xFF`	`HLT`	1	Stop the program.