Simple Assembler

A personal project via which I aim to learn a bit about assembly by programming an interpretive implementation of select opcode mnemonics.

Implemented Instructions

• ✔ MOV x, y Move the contents of register y into register x (x = y)

• ✔ INC x Increment register x by one (x++)

• ✔ DEC x Decrement register x by one (x--)

• ✔ ADD x, y Add the contents of register y to x (x += y)

• ✔ SUB x, y Subtract the contents of register y from x (x -= y)

• ✔ MUL x, y Multiply the contents of register x and y, store result in x (x *= y)

• ✔ DIV x, y Integer divide the contents of register x by y, store result in x (x /= y)

• ✔ JNZ x, y Jump y instructions if register x is Not Zero

• ✔ ; Comment, ignored by the interpreter

Planned Instructions

• ✘ label: Define a position within the code reachable by the label identifier

• ✘ call lbl Procedure call to the subroutine identified by the label lbl

• ✘ ret Return to the instruction that called the current subroutine

• ✘ CMP x, y Compare the contents of registers x and y (result used by other instructions)

• ✘ JNE lbl Jump to the label lbl if the values of the previous CMP were Not Equal

• ✘ JE lbl Jump to the label lbl if the values of the previous CMP were Equal

• ✘ JGE lbl Jump to the label lbl if register x was Greater than or Equal to y in the previous CMP

• ✘ JG lbl Jump to the label lbl if register x was Greater than y in the previous CMP

• ✘ JLE lbl Jump to the label lbl if register x was Lesser than or Equal to y in the previous CMP

• ✘ JL lbl Jump to the label lbl if register x was Lesser than y in the previous CMP

Further Instructions

Reference: Intel 80x86 ASM Opcodes