1//===------------ udivmodqi4.S - uint8 div & mod --------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// As described at
10// https://gcc.gnu.org/wiki/avr-gcc#Exceptions_to_the_Calling_Convention, the
11// prototype is `struct {uint8, uint8} __udivmodqi4(uint8, uint8)`.
12// The uint8 quotient is returned via R24, and the uint8 remainder is returned
13// via R25, while R23 is clobbered.
14//
15//===----------------------------------------------------------------------===//
16
17	.text
18	.align 2
19
20	.globl __udivmodqi4
21	.type  __udivmodqi4, @function
22
23__udivmodqi4:
24	sub     r25, r25           ; Initialize the remainder to zero.
25	ldi     r23, 9             ; Only loop 8 rounds for uint8.
26
27__udivmodqi4_loop:
28	adc     r24, r24
29	dec     r23
30	breq    __udivmodqi4_end
31	adc     r25, r25
32	cp      r25, r22           ; Compare with the divisor.
33	brcs    __udivmodqi4_loop
34	sub     r25, r22           ; Subtract the divisor.
35	rjmp    __udivmodqi4_loop
36
37__udivmodqi4_end:
38	com     r24                ; The uint8 quotient is returned via R24.
39	ret                        ; The uint8 remainder is returned via R25.
40