1//===------------- divmodhi4.S - sint16 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 {sint16, sint16} __divmodhi4(sint16, sint16)`.
12// The sint16 quotient is returned via R23:R22, and the sint16 remainder is
13// returned via R25:R24, while registers R21/R26/27/Rtmp and bit T in SREG
14// are clobbered.
15//
16//===----------------------------------------------------------------------===//
17
18 .text
19 .align 2
20
21#ifdef __AVR_TINY__
22 .set __tmp_reg__, 16
23#else
24 .set __tmp_reg__, 0
25#endif
26
27 .globl __divmodhi4
28 .type __divmodhi4, @function
29
30__divmodhi4:
31 bst r25, 7
32 mov __tmp_reg__, r23
33 brtc __divmodhi4_a
34 com __tmp_reg__
35 rcall __divmodhi4_b
36
37__divmodhi4_a:
38 sbrc r23, 7
39 rcall __divmodhi4_c
40 rcall __udivmodhi4 ; Call __udivmodhi4 to do real calculation.
41 sbrc __tmp_reg__, 7
42 rcall __divmodhi4_c
43 brtc __divmodhi4_exit
44
45__divmodhi4_b:
46 com r25
47 neg r24
48 sbci r25, 255
49 ret ; Return quotient via R23:R22 and remainder via R25:R24.
50
51__divmodhi4_c:
52 com r23
53 neg r22
54 sbci r23, 255
55
56__divmodhi4_exit:
57 ret ; Return quotient via R23:R22 and remainder via R25:r24.
58

source code of compiler-rt/lib/builtins/avr/divmodhi4.S