; vim: ft=nasm
%macro i_nop 0
    db 0x00
%endmacro
%define np i_nop


%macro i_halt 1
    db 0x01
    db %1
%endmacro
%define ht i_halt

; load <mem> <value>
%macro i_load 2
    db 0x10
    db %1
    db %2
%endmacro
%define ld i_load

; send <device> <mem>
%macro i_send 2
    db 0x20
    db %1
    db %2
%endmacro
%define sd i_send

; get <mem> <device>
%macro i_get 2
    db 0x21
    db %1
    db %2
%endmacro
%define gt i_get


; jlt <a>, <b>, <loc>
; a < b
%macro i_less 3
    db 0x50
    db %1
    db %2
    db %3
%endmacro
%define jl i_less


; jle <a>, <b>, <loc>
; a <= b
%macro i_leq 3
    db 0x51
    db %1
    db %2
    db %3
%endmacro
%define le i_leq

%define inp 0
%define disp 1
%define arith 2
%define tape 3


gt 0x00, inp
gt 0x01, inp
gt 0x02, inp
gt 0x03, inp
; [a, b, c, d] -> mem
sd tape, 0x00
sd tape, 0x01
sd tape, 0x02
sd tape, 0x03
; {a, b, c, d}
; [i[0], i[1], i[2], i[3] + i[0]]
; - add i[3] and i[0]

; [i[0], i[1], i[2], (i[3] + i[0]) ^ i[1]]
; - xor i[1] with i[3] + i[0], pop from arith

; [i[0] + i[1], i[1], i[2], (i[3] + i[0]) ^ i[1]]
; - add i[0] and i[1], pop from arith

; [i[0] + i[1], i[1], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - xor i[0] + i[1] with i[2], pop from arith

; [i[2], i[1], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - xor (i[0] + i[1]) ^ i[2] with i[0] + i[1], pop from arith

; [i[2], i[2] + i[1], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - add i[2] + i[1], pop from arith | store i[2] + i[1] in arith

; [i[2], i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - pop i[3] from tape use previous i[1] + i[2] from arith to xor

; [i[2], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - use previous i[1] + i[2] from arith to xor and pop

; [i[1], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - put i[2] in arith, pop i[1] from tape

; [i[2] + i[1], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - put i[1] in arith, add, pop

; [i[3], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - xor i[2] + i[1] with (i[2] + i[1]) ^ i[3]

; [i[2], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - put i[3] in arith, pop i[2] from tape

; [i[2] + i[3], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - put i[2] in arith, add to i[3]


; [i[0], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - put i[2] + i[3] in arith, pop i[0] from tape

; [(i[2] + i[3]) ^ i[0], (i[2] + i[1]) ^ i[3], (i[0] + i[1]) ^ i[2], (i[3] + i[0]) ^ i[1]]
; - xor in arith

; push all to tape
; pop all back into mem in correct spot


; routine for doing overflowing add
; [a, b]
; [255 - a, b]
; 255 - a < b
;    a = b - [255 - a]
; 255 - a >= b
;    a = a + b
; 



le 0x00, 0x01, label
sd disp, 0x00
label: 
    sd disp, 0x01