; brainfuck interpreter

; holds the brainfuck tape
@tape %%(1<<20)

; brainfuck macros (64-bit words, with anding)
; 1 word
macro bf<
	set [gp0] [gp0#-1]
end

; 1 word
macro bf>
	set [gp0] [gp0#1]
end

; 4 words
macro bf+
	push *[gp0]
	wadd 1
	bitand 255
	pop *[gp0]
end

; 4 words
macro bf-
	push *[gp0]
	wsub 1
	bitand 255
	pop *[gp0]
end

; 1+? words
macro bf.
	push *[gp0]
	; output
end

macro writeEOF
.if OnEOF == 0
	; 1 word
	set *[gp0] [zero]
.elseif OnEOF == -1
	; 1 word
	set *[gp0] 255
.else OnEOF == 1 ; unchanged - no writeback
	; 0 words
.endif
end

; 6+[0,1]+? words
macro bf,
	; input
	dup
	cmpne EOF
	cond jmp $$EOF
	pop *[gp0]
	jmp $$end
$$EOF:
	drop
	; 1 or 0 words
	writeEOF
$$end:
end

; 3 words before
macro bfLB (here) (dest)
	push *[gp0]
	popbool
	cond 0Eh jmp (dest)
	label (here)
end

; arguments inverted so that they are in the same order as the
; matching bfLB
; 3 words before
macro bfRB (dest) (here)
	push *[gp0]
	popbool
	cond jmp (dest)
	label (here)
end

macro incr_ua_ptr (ptr) (c_o)
	bitand 7 (c_o)
	push (ptr)
	shll 3
	bitor
	add 1
	select ((2^32-1)<<3) [SV]
	swap
	bitand 7
end

proc regcall bf_interp
	; [arg] = ptr to string to interpret
	; [gp0] = size of string to interpret
	; [jump] = address of this function
	
	set [gp1] @tape ; offset of start of tape
	
	
end