AQA-ASM

AQA-ASM is a simple assembly simulator designed for the weird AQA A Level instruction set. This simulator operates on 8-bit unsigned integers and features 13 general-purpose 8-bit registers labeled R0 to R12, along with 256 bytes of memory for loading instructions and storing variables.

Memory Layout

• Memory addresses are zero-indexed.
• The first byte after your program instructions is where the memory begins.
• For a program that occupies n bytes, you will have 256 - n memory addresses available for use.

Comments

You can include comments in your assembly code for clarity:

• Line comments begin with //
• Block comments are enclosed between /* and */

Core Instruction Set

The following table outlines the core instruction set available in AQA-ASM. Instructions can be delimited by either a semicolon (;) or a newline character, while instruction arguments are separated by commas.

Instruction	Description
LDR Rd, <memory ref>	Load the value in the memory location <memory ref> into register d
STR Rd, <memory ref>	Store the value in register d into the memory location <memory ref>
ADD Rd, Rn, <operand>	Add the value specified by <operand> to the value in register n and store the result in register d
SUB Rd, Rn, <operand>	Subtract the value specified by <operand> from the value in register n and store the result in register d
CMP Rn, <operand>	Compare the value stored in register n with the value specified by <operand>
MOV Rd, <operand>	Copy the value specified by <operand> into register d
B <label>	Branch to the label specified by <label>
B<condition> <label>	Branch to the label specified by <label> if the last comparison met the criterion specified by <condition>. Condition can be one of: EQ (equal to), NE (not equal to), GT (greater than), LT (less than)
AND Rd, Rn, <operand>	Perform a bitwise AND between the value in register n and the value specified by <operand>, storing the result in register d
ORR Rd, Rn, <operand>	Perform a bitwise OR between the value in register n and the value specified by <operand>, storing the result in register d
EOR Rd, Rn, <operand>	Perform a bitwise XOR between the value in register n and the value specified by <operand>, storing the result in register d
MVN Rd, <operand>	Perform a bitwise NOT on the value specified by <operand> and store it in register n
LSL Rd, Rn, <operand>	Perform a bitwise left shift on the value in register n by the number of bits specified by <operand>, storing the result in register d
LSR Rd, Rn, <operand>	Perform a bitwise right shift on the value in register n by the number of bits specified by <operand>, storing the result in register d
HALT	Terminate the program

Extra Instructions

In addition to the core instructions, the following extra instructions make it so programs can actually be debugged

Instruction	Description
PRINT Rd | <memory ref>	Print the numerical value stored in register d or at the memory address specified by <memory ref>
INPUT Rd | <memory ref>	Take numerical input and store it in register d or at the memory address specified by <memory ref>

Usage

To use AQA-ASM, follow these steps:

git clone https://github.com/Spacerulerwill/AQA-ASM
cd AQA-ASM
cargo run <filename>

This will compile and run your assembly program