SimASM

simulator that follows the ISA defined next. It is written in C++ and may use the Qt framework for the GUI.

ISA

Registers

The ISA has 4 general purpose registers, R0, R1, R2, and R3. The ISA also has a program counter register.

Stack

The ISA has a stack that is 4096 bytes in size. The stack pointer register points to the top of the stack.

Memory

The ISA has a shared memory to store code and data, with a variable size. direct access to memory is permitted.

ALU

The ALU is a 32-bit ALU that supports the following operations:

Comments

line comments are started with a ! and end at the end of the line.

LDA - Load Address

Load register reg1 with the contents of either the contents of reg2, or the memory var or a constant const. Memory regions loads (load into a variable, for instance) are NOT ALLOWED. There can be indirect loads, for instance LDA R1, R2 will load the contents of the memory address

STR - Store Register

Store the contents of reg or const into the memory var. Register regions stores (store into a Register,for instance t0) are NOT ALLOWED. There can be indirect stores, for instance STR R1, R2 will store the contents of R1 into the memory address

PUSH - Push to the top of the stack

Push the contents of reg/var or const into the top of the stack.

POP - Pop from the top of the stack

Pop the contents of the top of the stack into reg/var. Storing into Memory regions is NOT ALLOWED.

PEEK - Peek at the top of the stack

Check the value of the element at the top of the stack

PEEKN - Peek at the nth element of the stack

Check the value of the element at the nth position from the top of stack

Logical Operations

The logical operations are the following: there cannot be result stored in a memory region.

AND - Logical AND

Perform a Logical AND between reg1 and reg2 or const and store the result in reg1.

OR - Logical OR

Perform a Logical OR between reg1 and reg2 or const and store the result in reg1.

NOT - Logical NOT

Perform a Logical NOT on reg1 and store the result in reg1.

arithmetical operations

The arithmetical operations are the following: there cannot be result stored in a memory region.

ADD - Addition

Perform an addition between reg1 and reg2/var or const and store the result in reg1.

SUB - Subtraction

Perform a subtraction between reg1 and reg2/var or const and store the result in reg1.

MUL - Multiplication

Perform a multiplication between reg1 and reg2/var or const and store the result in reg1.

DIV - Division

Perform a division between reg1 and reg2/var or const and store the result in reg1.

MOD - Modulo

Perform a modulo between reg1 and reg2/var or const and store the result in reg1. The operation is defined as first argument is the modulo of the second argument.

INC - Increment

Increment the contents of reg1 by 1.

DEC - Decrement

Decrement the contents of reg1 by 1.

comparison operations and jumps

BEQ - Branch if Equal

Branch to the label if reg1 is equal to reg2 or const.

BNE - Branch if Not Equal

Branch to the label if reg1 is not equal to reg2 or const.

BBG - Branch if Bigger

Branch to the label if reg1 is bigger than reg2 or const.

BSM - Branch if Smaller

Branch to the label if reg1 is smaller than reg2 or const.

JMP - Jump

Jump to the label.

Misc

HLT - Halt

Halt the execution of the program.

SRR - Shift Register Right

Shift the contents of reg1 to the right by the amount of bits specified in const.

SRL - Shift Register Left

Shift the contents of reg1 to the left by the amount of bits specified in const.