fp_mode.c revision 360784 
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     0x1000
22
23#ifndef __ARM_FP
24// For soft float targets, allow changing rounding mode by overriding the weak
25// __arm_fe_default_rmode symbol.
26FE_ROUND_MODE __attribute__((weak)) __arm_fe_default_rmode = FE_TONEAREST;
27#endif
28
29FE_ROUND_MODE __fe_getround() {
30#ifdef __ARM_FP
31  uint32_t fpscr;
32  __asm__ __volatile__("vmrs  %0, fpscr" : "=r" (fpscr));
33  fpscr = fpscr >> ARM_RMODE_SHIFT & ARM_RMODE_MASK;
34  switch (fpscr) {
35    case ARM_UPWARD:
36      return FE_UPWARD;
37    case ARM_DOWNWARD:
38      return FE_DOWNWARD;
39    case ARM_TOWARDZERO:
40      return FE_TOWARDZERO;
41    case ARM_TONEAREST:
42    default:
43      return FE_TONEAREST;
44  }
45#else
46  return __arm_fe_default_rmode;
47#endif
48}
49
50int __fe_raise_inexact() {
51#ifdef __ARM_FP
52  uint32_t fpscr;
53  __asm__ __volatile__("vmrs  %0, fpscr" : "=r" (fpscr));
54  __asm__ __volatile__("vmsr  fpscr, %0" : : "ri" (fpscr | ARM_INEXACT));
55  return 0;
56#else
57  return 0;
58#endif
59}
60