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tclang

tclang is an experimental programming language. The goal is to develop a high level assembly-like language for a stack machine which also has random access memory and is portable and easily implementable in a number of programming languages. The ideal use case for such a language is as an intermediate language for a compiler or interpreter.

Status

This is early days, and as such, there is a lot of churn. Changes are likely.

Example

This little demo prints the squares of number from 1 to 10. It shows off the stack, main memory, looping, sub-routines, and output.

MAIN
        OTS Squares of integers from 1..10
        LDI 1
        STA 42
        LDI 10
        STA 88
LOOP
        LDA 88
        LDA 42
        CLE
        BEZ DONE
        LDA 42
        JAL SQR
        OTI
        LDI 10
        OCH
        LDA 42
        INC
        STA 42
        BRA LOOP
DONE
        HLT
SQR
        DUP
        MUL
        RTN

Syntax

  • comment - begins with an octothorp (#). Matches ^#.*$.
  • label - up to 7 characters long and may not begin with a blank ( ) nor an octothorp (#). Matches ^[^ #]{1,7}.
  • opcode - 3 upper case letters. Matches [A-Z]{3}.
  • operand - dependent on opcode.

Grammar

program	: lines
	;

lines	: lines line
	| line
	;

line	: comment '\n'
	| code '\n'
	;

comment	: '#' [anything]

code	: label opcode operand
	| opcode operand
	| opcode
	| label
	;

Source Code Format

Lines of source code are fixed length records.

  • Position 1 through 7 - label or blanks ( ) or # in position 1 for a comment line.
  • Position 8 - blank ( )
  • Position 9 through 11 - opcode.
  • Position 12 - blank ( )
  • Position 13 through 72 - operand.

Environment

  • A memory cell may hold a 32 bit signed integer.
  • There are 32,768 random access memory cells.
  • There is a stack with 8,192 memory cells.
  • There is a call stack with 512 memory cells.

Virtual Machine Description

The virtual machine has a stack and main memory. Opcodes operate on the stack and accept 0 or 1 operands with effect the stack. For example, LDI 2 pushes 2 onto the stack. ADD pops the top two numbers off of the stack, sums them, and pushes the result onto the stack. Values can be moved between the stack and main memory.

opcodes

Arithmetic

code operand description
ADD Pops the top two numbers off of the stack, adds them, and pushes the result onto the stack.
SUB Pops the top two numbers off of the stack, subtracts them, and pushes the result onto the stack.
MUL Pops the top two numbers off of the stack, multiplies them, and pushes the result onto the stack.
DIV Pops the top two numbers off of the stack, divides them, and pushes the result onto the stack.
MOD Pops the top two numbers off of the stack, divides them, and pushes the remained onto the stack.
INC Pops the top number off of the stack, adds 1, and pushes the result onto the stack.
DEC Pops the top number off of the stack, subtracts 1, and pushes the result onto the stack.

Bitwise

code operand description
AND Pops the top two numbers off of the stack, performs a bitwise AND, and pushes the result onto the stack.
BLS Pops the top two numbers off of the stack, performs a binary left shift, and pushes the result onto the stack.
BRS Pops the top two numbers off of the stack, performs a binary right shift, and pushes the result onto the stack.
NOT Pops the top two numbers off of the stack, performs a bitwise NOT, and pushes the result onto the stack.
OAR Pops the top two numbers off of the stack, performs a bitwise OR, and pushes the result onto the stack.
XOR Pops the top two numbers off of the stack, performs a bitwise XOR, and pushes the result onto the stack.

Flow Control

code operand description
BRA label Branch always to the label.
BEZ label Pops the top number off of the stack and branches to the label when the number is zero.
BNZ label Pops the top number off of the stack and branches to the label when the number is non-zero.

Comparisons

code operand description
CEQ Pops the top two values of the stack. Pushes 1 onto the stack if equal, else pushes 0.
CNE Pops the top two values of the stack. Pushes 1 onto the stack if not equal, else pushes 0.
CLE Pops the top two values of the stack. Pushes 1 onto the stack if less than or equal, else pushes 0.
CLT Pops the top two values of the stack. Pushes 1 onto the stack if less than, else pushes 0.
CGE Pops the top two values of the stack. Pushes 1 onto the stack if greater than or equal, else pushes 0.
CGT Pops the top two values of the stack. Pushes 1 onto the stack if greater than, else pushes 0.

Sub-routines

code operand description
JAL label Call the sub-routine identified by label.
RTN Return to the location where the sub-routine was called.

Stack Manipulation

code operand description
DUP duplicates the value at the top of the stack.

Data Load / Store

code operand description
LDI number Loads the immediate value and pushes it onto the stack.
LDA address Loads a value from the given memory address (hex) onto the stack.
STA address Stores a value to the given memory address (hex) from the stack.

Input / Output

code operand description
ICH Reads a character from standard input and pushes the value onto the stack.
INI Reads an line from standard input, converts text digits to a number, and pushes it onto the stack.
OCH Pops the top of the stack and prints it as a character to standard output.
OTI Pops the top of the stack and prints it as an integer to standard output.
OTS string Prints the string to standard output.

Misc

code operand description
HLT Halts execution of the program.