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README.md

SomeVM

=======

A register-based bytecode interpreter VM.

Has two modes:

  • REPL mode (though the Print part is manual!).
  • Run mode(?) (like reading from a file and just running it, etc)

REPL mode is functional, with a currently assembly-like sort of intermediate language (IL).
(Apparently I removed REPL mode at some point...)
example hello world:

  > load $0 "hello, world"
  > print $0
  "hello, world"
  > 

Run mode is functional, using the same IL (hesitantly named "SVML"):

load $0 "hello, world"
print $0

Basic arithmetic (+, -, *, /, %) is supported, as well as logical operators (!, <, <=, >, >=, ==, !=). Also, a "print" instruction.

Basic syntax:

  • integers prepended with a '$' is an index to a register.
  • Anything between a pair of double quotes (") is a string
  • "true" and "false" (no quotes) are bools.
  • Instructions and their arguments are simply separated by spaces

Current VM instructions:

  • <instruction> - <description>

    • <argument list>
  • load - loads a constant or another the value of another register to the given register

    • register to load to
    • a value OR another register to load from
  • add - adds the values at the two registers and stores the result

    • register to write to
    • first register to add
    • second register to add
  • sub - subtracts the values at the two registers and stores the result (first - second)

    • register to write to
    • first register to subtract
    • second register to subtract
  • mult - multiplies the values at the two registers and stores the result

    • register to write to
    • first register to multiply
    • second register to multiply
  • div - divides the values at the two registers and stores the result (first / second)

    • register to write to
    • first register to divide
    • second register to divide
  • mod - performs modulus on the values at the two registers and stores the result (first % second)

    • register to write to
    • first register to perform modulo with
    • second register to perform modulo with
  • neg - negates (equivalent to multiplying by -1) the value at the given register and stores the result

    • register to write to
    • register with the value to negate
  • fadd - adds the (floating point) values at the two registers and stores the result

    • register to write to
    • first register to add
    • second register to add
  • fsub - subtracts the (floating point) values at the two registers and stores the result (first - second)

    • register to write to
    • first register to subtract
    • second register to subtract
  • fmult - multiplies the (floating point) values at the two registers and stores the result

    • register to write to
    • first register to multiply
    • second register to multiply
  • fdiv - divides the (floating point) values at the two registers and stores the result (first / second)

    • register to write to
    • first register to divide
    • second register to divide
  • fneg - negates (equivalent to multiplying by -1) the value at the given register and stores the result

    • register to write to
    • register with the value to negate
  • casti - casts a value to an integer

    • register to write to
    • register to read from
  • castf - casts a value to a floating point value

    • register to write to
    • register to read from
  • lt - stores the result of first < second

    • register to write to
    • first register to compare with
    • second register to compare with
  • lteq - stores the result of first <= second

    • register to write to
    • first register to compare with
    • second register to compare with
  • gt - stores the result of first > second

    • register to write to
    • first register to compare with
    • second register to compare with
  • gteq - stores the result of first >= second

    • register to write to
    • first register to compare with
    • second register to compare with
  • eq - stores the result of first == second

    • register to write to
    • first register to compare with
    • second register to compare with
  • neq - stores the result of first != second

    • register to write to
    • first register to compare with
    • second register to compare with
  • flt - stores the result of (floating point) first < second

    • register to write to
    • first register to compare with
    • second register to compare with
  • flteq - stores the result of (floating point) first <= second

    • register to write to
    • first register to compare with
    • second register to compare with
  • fgt - stores the result of (floating point) first > second

    • register to write to
    • first register to compare with
    • second register to compare with
  • fgteq - stores the result of (floating point) first >= second

    • register to write to
    • first register to compare with
    • second register to compare with
  • feq - stores the result of (floating point) first == second

    • register to write to
    • first register to compare with
    • second register to compare with
  • fneq - stores the result of (floating point) first != second

    • register to write to
    • first register to compare with
    • second register to compare with
  • not - inverts the boolean value at the given register and stores the result

    • register to write to
    • register to invert
  • and - boolean ands the values at the given registers and stores the result

    • register to write to
    • register of first boolean
    • register of second boolean
  • or - boolean ors the values at the given registers and stores the result

    • register to write to
    • register of first boolean
    • register of second boolean
  • xor - boolean xors the values at the given registers and stores the result

    • register to write to
    • register of first boolean
    • register of second boolean
  • bnot - bitwise inverts the value at the given register and stores the result

    • register to write to
    • register to invert
  • band - bitwise ands the values at the given registers and stores the result

    • register to write to
    • register of first value
    • register of second value
  • bor - bitwise ors the values at the given registers and stores the result

    • register to write to
    • register of first value
    • register of second value
  • bxor - bitwise xors the values at the given registers and stores the result

    • register to write to
    • register of first value
    • register of second second
  • bsl - bitwise shifts-left the value at the given registers and stores the result

    • register to write to
    • register of value to shift
    • register of amount to shift by
  • bsr - bitwise shifts-right the value at the given registers and stores the result

    • register to write to
    • register of value to shift
    • register of amount to shift by
  • jmpt - if the test is true, jumps to the given instruction index (only within the current call frame)

    • registry index to test if true
    • instruction index to jump to
  • jmpf - if the test is false, jumps to the given instruction index (only within the current call frame)

    • registry index to test if false
    • instruction index to jump to
  • rjmpt - if the test is true, jumps to a instruction by the given value (only within the current call frame)

    • registry index to test if true
    • instruction offset to jump by
  • rjmpf - if the test is false, jumps to a instruction by the given value (only within the current call frame)

    • registry index to test if false
    • instruction offset to jump by
  • jmp - moves execution to the specified instruction (only within the current call frame)

    • instruction index
  • rjmp - moves execution to the instruction at the given offset (only within the current call frame)

    • offset to jump by
  • call - creates a new call frame and moves execution to it

    • number of arguments to send to the function
    • registry index of the start of the arguments
    • function index (TODO: or function name)
  • ret - returns from the current call frame to the previous (if no previous, exits)

    • number of values to return
    • registry index of start of returns
  • nop - "No operation" - self explanatory

    • any arguments are ignored
  • print - prints out the value at the given register

    • register to print from

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A register-based bytecode interpreter VM.

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