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.
26 CRT_FE_ROUND_MODE __attribute__((weak)) __arm_fe_default_rmode =
27     CRT_FE_TONEAREST;
28 #endif
29 
30 CRT_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 
51 int __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