1//===----- lib/arm/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 ARM_TONEAREST 0x0
14#define ARM_UPWARD 0x1
15#define ARM_DOWNWARD 0x2
16#define ARM_TOWARDZERO 0x3
17#define ARM_RMODE_MASK (ARM_TONEAREST | ARM_UPWARD | \
18 ARM_DOWNWARD | ARM_TOWARDZERO)
19#define ARM_RMODE_SHIFT 22
20
21#define ARM_INEXACT 0x10
22
23#ifndef __ARM_FP
24// For soft float targets, allow changing rounding mode by overriding the weak
25// __arm_fe_default_rmode symbol.
26CRT_FE_ROUND_MODE __attribute__((weak)) __arm_fe_default_rmode =
27 CRT_FE_TONEAREST;
28#endif
29
30CRT_FE_ROUND_MODE __fe_getround(void) {
31#ifdef __ARM_FP
32 uint32_t fpscr;
33 __asm__ __volatile__("vmrs %0, fpscr" : "=r" (fpscr));
34 fpscr = fpscr >> ARM_RMODE_SHIFT & ARM_RMODE_MASK;
35 switch (fpscr) {
36 case ARM_UPWARD:
37 return CRT_FE_UPWARD;
38 case ARM_DOWNWARD:
39 return CRT_FE_DOWNWARD;
40 case ARM_TOWARDZERO:
41 return CRT_FE_TOWARDZERO;
42 case ARM_TONEAREST:
43 default:
44 return CRT_FE_TONEAREST;
45 }
46#else
47 return __arm_fe_default_rmode;
48#endif
49}
50
51int __fe_raise_inexact(void) {
52#ifdef __ARM_FP
53 uint32_t fpscr;
54 __asm__ __volatile__("vmrs %0, fpscr" : "=r" (fpscr));
55 __asm__ __volatile__("vmsr fpscr, %0" : : "ri" (fpscr | ARM_INEXACT));
56 return 0;
57#else
58 return 0;
59#endif
60}
61

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