; Tremolo library
; Copyright (C) 2009 Robin Watts for Pinknoise Productions Ltd

	AREA	|.text|, CODE, READONLY

	EXPORT	render_line_arm_low

render_line_arm_low
	; r0 = n
	; r1 = d
	; r2 = floor
	; r3 = base
	; <> = err
	; <> = adx
	; <> = ady
	MOV	r12,r13
	STMFD	r13!,{r4-r6,r11,r14}
	LDMFD	r12,{r11,r12,r14}	; r11 = err
					; r12 = adx
					; r14 = ady
rl_loop
	LDR	r4, [r1]		; r4 = *d
	LDR	r5, [r2], r3,LSL #2	; r5 = *floor    r2 = floor+base
	SUBS	r11,r11,r14		; err -= ady
	MOV	r4, r4, ASR #6
	MUL	r5, r4, r5		; r5 = MULT31_SHIFT15
	ADDLT	r11,r11,r12		; if (err < 0) err+=adx
	ADDLT	r2, r2, #4		;              floor+=1
	SUBS	r0, r0, #1
	STR	r5, [r1], #4
	BGT	rl_loop

	LDMFD	r13!,{r4-r6,r11,PC}

	END