Textmode / TMVM

Textmode's Virtual Macaroni: A VM for, er...we'll get back to you.
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Textmode Virtual Macaroni, or TMVM, is a simple, poorly-designed, simulation of a register-based system. It currently has an addressable memory space of 256 segments containing 256 bytes (00..ff) each, for a total of 65536 bytes (or 64KiB). It runs at a nominal speed of 1MHz.

It's not presently useful for much of anything, it is also likely to be unstable and unreliable, so have fun! :D

In all honesty, TMVM could be used as a toy system, or as an instructive aid (once it's more stable). It's nigh-complete lack of higher-level features or space means it's effectively a void, an empty sandpit, in which you can do pretty much anything you want without stepping on anything's toes.

Note: TMVM is still under development, expect fundamental design and API changes.

TMVM is created by DMB/Textmode, while ignoring the well thought-out advice of many helpful people who didn't realise that TMVM was meant to be very dubious in quality and use.

IRC: #TMVM on irc.freenode.org:8001
Project: https://github.com/Textmode/TMVM

Requirements

* Lua 5.1 or better.
* A sense of humor.

Usage

TMVM is divided into two basic parts; the machine (AKA Core), and the asm (AKA FUASSM). There is also the support lib bitfield.

The ASM is the component that takes programs expressed in FUASSM code. It is a runnable module.

Machine represents functions for creating and managing individual TMVMs. loading data into their memory, and controlling their operation. It is not yet a runnable module, but its likely to become one in the future.

Bitfield contains utility functions for dealing with numbers as bitfields. It provides bitwise operations, binary indexing and similar features required by the core but not provided by lua.

Machine

machine.lua can be required normally.

As a module, machine exposes the following functions: module:new(opt_name) returns: machine Creates a new machine with the given name. If no name is given, a default name will be provided.

(VM):signal(opt_signal)
    returns: signal, description
    If given no parms, returns the current signal, and a (short) textual
     description.
    Otherwise it triggers the given signal.
    Tf another signal has yet to be cleared, it will trigger a double
    fault.
    If a double-fault is uncleared, a triple-fault.
    Triggering the signal NONE will clear the signal.

(VM):load(opt_start, data_string_or_table)
    returns: (nothing)
    Attempts to load the given data into the machine's memory.
    If start is omitted, it will load at address 0, segment 0.

(VM):cycle(opt_num)
    returns: machine_state
    completes num instruction cycles. if num is omitted, it will assume
     1 cycle.

(VM):run(bool_show_status_dumps) -- Broken!
    returns: (nothing)
    Attempts to run the machine at it's base speed.
    if passed true, it will call VM:dump() roughly 1/s

(VM):dump()
    returns: (nothing)
    Prints state information on the current machine

ASM

asm.lua can be required normally. Additionally, it is a runnable module and can be directly run.

As a program, asm.lua takes the name of a FUASM source file, and optionally the name of an output file. if no output file is given, it outputs to the same filename with .crap replacing it's original extension: thus 'test.asm' outputs to 'test.crap'. Regardless, it also prints a lua-formatted table of hex digits representing the assembled binary.

As a module, it exposes the following functions:

asm.load(filename)
    returns: preparsed_chunk
    loads the given file and returns a normalised chunk, suitable for
     further parsing.

asm.scrub(string)
    returns: preparsed_chunk
    processes the given string into a pre-parsed chunk, suitable for
     further parsing.

asm.parse(chunk)
    returns: final_bytestring
    takes a string or pre-parsed chunk, and returns a fully-assembled
     chunk as a string, suitable for saving or loading into a machine.

Bitfield

Bitfield is a support library, providing emulated bitwise operations for Lua.

As a module, it exposes the following functions: bitfield:new(opt_num, opt_width) returns: bitfield Creates and returns a new bitfield. If opt_num is provided, the initial value of the bitfield will be the binary representation of that number, otherwise it will be zero. If opt_width is provided it will be used as the effective bitwidth of the bitfield, otherwise it will default to 16 bits.

(bf)[n]
    returns: bit
    Returns true if the nth bit is set, otherwise returns false. if a bit
     outside the range of the bitfield's width is requested, it returns
     nil instead (which is also logically false)

(bf)[n] = v 
    returns: (nothing)
    Sets the nth bit of bf to the truth value of v

(bf):NOT()
    returns: num
    Negates the value of bf. Additionally returns the resulting value.
        NOT 1 -> 0
        NOT 0 -> 1

(bf):AND(b)
    returns: num
    ANDs the value of bf with b. Additionally returns the resulting
     value.
        0 AND 0 -> 0
        0 AND 1 -> 0
        1 AND 0 -> 0
        1 AND 1 -> 1

(bf):OR(b) 
    returns: num
    ORs the value of bf with b. Additionally returns the resulting value.
        0 OR 0 -> 0
        0 OR 1 -> 1
        1 OR 0 -> 1
        1 OR 1 -> 1

(bf):XOR(b) 
    returns: num
    XORs the value of bf with b. Additionally returns the resulting
     value.
        0 XOR 0 -> 0
        0 XOR 1 -> 1
        1 XOR 0 -> 1
        1 XOR 1 -> 0

(bf):NAND(b) 
    returns: num
    NANDs the value of bf with b. Additionally returns the resulting
     value.
        0 NAND 0 -> 1
        0 NAND 1 -> 1
        1 NAND 0 -> 1
        1 NAND 1 -> 0

(bf):NOR(b) 
    returns: num
    NORs the value of bf with b. Additionally returns the resulting value.
        0 NOR 0 -> 1
        0 NOR 1 -> 0
        1 NOR 0 -> 0
        1 NOR 1 -> 0

(bf):XNOR(b) 
    returns: num
    XNORs the value of bf with b. Additionally returns the resulting
     value.
        0 XNOR 0 -> 1
        0 XNOR 1 -> 0
        1 XNOR 0 -> 0
        1 XNOR 1 -> 1

(bf):shift(n, sign-ext) 
    returns: num
    Shifts the value of bf by n. Additionally returns the resulting
     value.
    Positive values shift left, negative values shift right. if sign-ext
     is true, then the sign bit will be extended during a right-shift.