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.
26 CRT_FE_ROUND_MODE __attribute__((weak)) __aarch64_fe_default_rmode =
27     CRT_FE_TONEAREST;
28 #endif
29 
30 CRT_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 
51 int __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