Neander Machine

This project is a study on compilers. Here, a custom processor architecture is defined, along with a set of custom machine language instructions. In addition to the virtual machine, there is the compiler, which is capable of recognizing and compiling a simple grammar of mathematical expressions.

This project attempts to answer some questions such as:

1. How can I perform certain mathematical expressions without using stack memory and with a very limited set of instructions?
2. How can I generate code from a parser?
3. How can I create an efficient virtual machine?

This project contains:

• Compiler/parser
• Assembler
• Virtual Machine

Create folder comp before running make file.

Simple execution:

make run FILE=equation.mth

Clear data under comp/.

make clear

You can write expressions like the following: (2 + 3) + 2.

First, the expression passes through the parser, which calls the lexer to collect each token.

The parser may execute the following actions and create the assembly code.

Open parentesis
Write 2 to addr 192
Write 3 to addr 193
Symbol +
Close parentesis
Write 2 to addr 194
Symbol +

While the parser, using a recursive descent analyzer, creates the tree of operations, it generates the assembly code, which will be compiled afterward.

ADDR
    c0 $add0
    c1 $add1
    c2 $add2
END

The assembly (with customized syntax) includes several sections. The ADDR section contains address mappings, which are arbitrarily defined. In this example, the parser maps the label $add0 to the address c0. Everything stored in c0 is accessible via the label $add0.

DATA
    0 fa
    1 fb
    0 fc
    02 $add0
    03 $add1
    02 $add2
END

The DATA section is where the data is stored for each previusly defined address (variable value). In this example, the value 02 is mapped to the address $add0. This means that any operation referencing the label $add0 will access the value 02. Similarly, other values are mapped to their respective addresses. It is possible to address instead labes like 0 mapped to fa.

TEXT
    LDA $add0
    ADD $add1
    STA $add0

    LDA $add0
    ADD $add1
    STA $add0

    HLT
END

TEXT section has the assembly code. It consumes the addresses or labels. Jump instructions may use labels as well. Take a look at neander and ndr-c/assembler/assembler.c for all instructions.

The order of the sections must be preserved.