1//===----- lib/aarch64/fp_mode.c - Floaing-point mode utilities ---*- C -*-===//
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#include <stdint.h>
10
11#include "../fp_mode.h"
12
13#define AARCH64_TONEAREST 0x0
14#define AARCH64_UPWARD 0x1
15#define AARCH64_DOWNWARD 0x2
16#define AARCH64_TOWARDZERO 0x3
17#define AARCH64_RMODE_MASK (AARCH64_TONEAREST | AARCH64_UPWARD | \
18 AARCH64_DOWNWARD | AARCH64_TOWARDZERO)
19#define AARCH64_RMODE_SHIFT 22
20
21#define AARCH64_INEXACT 0x10
22
23#ifndef __ARM_FP
24// For soft float targets, allow changing rounding mode by overriding the weak
25// __aarch64_fe_default_rmode symbol.
26CRT_FE_ROUND_MODE __attribute__((weak)) __aarch64_fe_default_rmode =
27 CRT_FE_TONEAREST;
28#endif
29
30CRT_FE_ROUND_MODE __fe_getround(void) {
31#ifdef __ARM_FP
32 uint64_t fpcr;
33 __asm__ __volatile__("mrs %0, fpcr" : "=r" (fpcr));
34 fpcr = fpcr >> AARCH64_RMODE_SHIFT & AARCH64_RMODE_MASK;
35 switch (fpcr) {
36 case AARCH64_UPWARD:
37 return CRT_FE_UPWARD;
38 case AARCH64_DOWNWARD:
39 return CRT_FE_DOWNWARD;
40 case AARCH64_TOWARDZERO:
41 return CRT_FE_TOWARDZERO;
42 case AARCH64_TONEAREST:
43 default:
44 return CRT_FE_TONEAREST;
45 }
46#else
47 return __aarch64_fe_default_rmode;
48#endif
49}
50
51int __fe_raise_inexact(void) {
52#ifdef __ARM_FP
53 uint64_t fpsr;
54 __asm__ __volatile__("mrs %0, fpsr" : "=r" (fpsr));
55 __asm__ __volatile__("msr fpsr, %0" : : "ri" (fpsr | AARCH64_INEXACT));
56 return 0;
57#else
58 return 0;
59#endif
60}
61

source code of compiler-rt/lib/builtins/aarch64/fp_mode.c