;bool bigint_frombytes(BIGINT dest, const void *restrict src, size_t len, bool big_endian);
bigint_frombytes:
	call ti._frameset0
; (ix + 6) = dest
; (ix + 9) = src
; (ix + 12) = len
; (ix + 15) = big_endian

; ensure that src and dest don't overlap
	ld hl, (ix + 9)
	ld de, (ix + 6)
	xor a
	sbc hl, de
	jr z, .exit
	add hl, de
	push hl, de

; zero out dest
		xor a
		ld (de), a
		inc de
		ld hl, (ix + 9)
		ld bc, 31
		ldir

; restore src and dest, load num bytes to copy
	pop de,hl
	ld bc, (ix + 12)
	ld a, (ix + 15)
	or a
	jr nz, copy_bigendian
	add hl, bc
	dec hl
.loop_littleendian:
	ldi
	jr po, .return_1
	dec hl
	dec hl
	jr loop_littleendian
.copy_bigendian:
; add 32 - bc to de
	ldir
.return_1:
	ld a, 1
.exit:
	ld	sp, ix
	pop	ix
	ret