EduCPU Code

# Subroutine call
macro .call @lb
    # Push previous return addr onto stack
    subi r30,r30,1
    st r31,r30,0
    
    # Make the call
    bt @lb,r31
    nop             # branch delay slot
    
    # Pop previous return addr
    ld r31,r30,0
    addi r30,r30,1
end

# Return from sub
macro .ret
    jmp r31
end

# define some constants
@start = 10     # Initial value of some variable
@n = 3          # Number of loop iterations

# First instruction of program

    ori r2,r0,@start    # Load consts into registers
    ori r1,r0,@n
    out r2
    out r1
@loop:
    .call @mysub        # Call the subroutine
    out r2
    subi r1,r1,1        # Decrement loop counter
    out r1
    bne @loop           # Branch if still looping
    nop                 # Branch delay slot
    nop                 # Let the pipeline flush before halt
    nop
    halt                # Stop the program

# A subroutine (which doesn't do a lot)
@mysub:
    addi r2,r2,1
    .ret
    
    nop