.macro breakpoint ; $02 isn't a valid instruction, the emulator will see this and halt, dump memory contents
        .byte $02
    .endm

    .macro pop ; drops a data stack cell
        inx
        inx
    .endm
    
    .macro pop2 ; drops 2 data stack cells
        inx
        inx
        inx
        inx
    .endm
    
    .macro push ; push a data stack cell
        dex
        dex
    .endm
    
    .macro push2 ; push 2 data stack cells
        dex
        dex
        dex
        dex
    .endm
    
    .macro push_char, char; pushes an ascii character code onto the stack
        lda \char
        push
        sta 0, x ; char low byte
        stz 1, x ; char high byte
    .endm
    
    .macro push_coords,  coord_x, coord_y ; push a set of (x,y) coordinates onto the data stack
        lda \coord_x
        push
        sta 0, x ; low byte
        stz 1,x ; high byte is zero
        lda \coord_y
        push
        sta 0,x ; same here
        stz 1,x
    .endm
    
    .macro to_r ; pop the top of the stack off and save it in the return (hardware) stack: (n -- )
        lda 1, x
        pha
        lda 0, x
        pha
        pop
    .endm
    
    .macro from_r ; pop the top of the return stack off and put it on the data stack: ( -- n)
        push
        pla
        sta 0, x
        pla
        sta 1, x
    .endm