Instruction Categories¶

Not all of these instructions will be present in an ISA, in the exact given format. This is to give a general idea as to what kinds of instructions you will run into.

Arithmetic Operations¶

add
sub
mul
div
mod

Operation Formats¶

Operations can be performed between two registers, or a register and an immediate. This result will be stored in a destination register.

Logical Operations¶

and
or
not

Operation Formats¶

and and or are typically performed only between two registers. This result is stored in a destination register. not accepts only one source, and stores its negation in the destination register.

Branching Operations¶

bz (RS) (addr) - branches to address (addr) if register (RS) is storing value 0.
bnz (RS) (addr) - branches to address (addr) if register (RS) is not storing value 0.

Alternative Branching Approaches¶

be, blt, bgt - compare the value of two registers, and branch depending on them.
cmp - sets the value of flags, and depending on these flags the next instruction may branch somewhere.

An ISA will typically use one of these approaches to branch

Function Operations¶

call (lbl) - calls the function referred to with label.
ret - returns from the current function

Data Transfer / Persistence¶

ld (RD) (addr) - loads value from memory address (addr) to register (RD)
st (RS) (addr) - stores value in register (RS) to memory address (addr)
mov (RD) (RS / imm) - stores value from either a source register (RS) or an immediate (imm) to a destination register (RD)

Stack Operations¶

push (RS) - pushes value of (RS) on the stack
pop (RD) - pops the value at the top of stack into (RD)

IO Instructions¶

input (RD) - inputs a value into a register (RD)
output (RS) - outputs the value of register (RS)