Operations
----------

Stack operations: (0x00~0x1f)
   pushn [int]          Push int
   pushr [float]        Push float (real)
   pushs [string]       Push string
   pshcn [index]        Push int from constant list
   pshcr [index]        Push float from constant list
   pshcs [index]        Push string from constant list
   pushf [function]     Push function id
   pushz                Push zero (or false)
   pusht                Push true
   newa [array]         Push (create) empty array
   newt [table]         Push (create) empty table
   pop
   dup

Local variables: (0x20~0x2f)
   setl [int]           Set stack top as indexed local variable
   getl [int]           Get indexed local variable and place on stack
   setg [int]           Set global variable
   getg [int]           Get global variable

Function operations: (0x30~0x3f)
   call [n_pars]        Enter function on stack toplevel (passing n next stack values as parameters)
   ret                  Leave a function (return value in stack)
   retn                 Leave a function (return nil)

Control flow: (0x40~0x4f)
   bz [pc]              Branch if zero
   bnz [pc]             Branch if not zero
   jmp [pc]             Unconditional jump
* Jumps can only happen within the same function.

Logical/arithmetic: (0x50~0x6f)
   sum                  Sum top 2 values in stack
   sub                  Subtract top 2 values in stack
   mul                  Multiply top 2 values in stack
   div                  Float division
   idiv                 Integer division
   eq                   Equality
   neq                  Inequality
   lt                   Less than
   lte                  Less than or equals
   gt                   Greater than
   gte                  Greater than or equals
   and                  Bitwise AND
   or                   Bitwise OR
   xor                  Bitwise XOR

Table and array operations: (0x70~07xf)
   getkv                Get table's value based on key (pull 1 value, push 1 value)
   setkv                Set table's key and value (pull 2 values from stack)
   geta                 Get array's position value
   seta                 Set array's position value (pull 2 values from stack)
   appnd                Add value to the end of array
   next                 Push the next pair into the stack (for loops)
   smt                  Set value metatable
   mt                   Get value metatable

Other value operations: (0x80~0x8f)
   len                  Get table, array or string size
   type                 Get type from value at the top of the stack
   cast [type]          Cast type to another type
   ver                  Return VM version

External code: (0x90~0x9f)
   cmpl                 Compile code to assembly
   asmbl                Assemble code to bytecode format
   load                 Load bytecode as function (will place function on stack)

Error handling: (0xa0~0xaf)
   ???


Bytecode format
---------------

The bytecode file is composed of the following sections:

 * [0x0] 16-byte header
            [0:3]: Magic
            [4]:   VM format
 * [0x1] Index: pointers to each one of the sections, up to 8
            Each pointer: 4 bytes
 * [0x2] Constants: all constants (such as strings) used in the code
            * Table of 4-byte constant indexes with pointer to constant
            * Raw constant data
 * [0x3] Functions: Pointer to functions within the code
            [0:3]: function pointer
            [4:5]: number of parameters
            [6:7]: number of local variables
 * [0x4] Code: executable code
            [1-byte]:   operation
            [variable]: operand (see value encoding below)
 * [0x5] Debugging info
            ???

The max file size is 2 Gb.

## Values can be encoded in the following ways:
 * The type is defined by the operator.
 * Encoding varies according to the type:
    int:    use protobuf format
    float:  4-bit floating point
    string: int-defined length, followed by the string proper - no null terminator
 * Constant indexes and function ids are encoded as ints


Internal handling of values
---------------------------

## Supported types
  Nil             0
  Integer         1
  Float           2
  String          3
  Array           4
  Table           5
  Function        6
  NativePointer   7

## Internal format
  ???