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 FE_ROUND_MODE __attribute__((weak)) __aarch64_fe_default_rmode = FE_TONEAREST;
27 #endif
28 
29 FE_ROUND_MODE __fe_getround() {
30 #ifdef __ARM_FP
31   uint64_t fpcr;
32   __asm__ __volatile__("mrs  %0, fpcr" : "=r" (fpcr));
33   fpcr = fpcr >> AARCH64_RMODE_SHIFT & AARCH64_RMODE_MASK;
34   switch (fpcr) {
35     case AARCH64_UPWARD:
36       return FE_UPWARD;
37     case AARCH64_DOWNWARD:
38       return FE_DOWNWARD;
39     case AARCH64_TOWARDZERO:
40       return FE_TOWARDZERO;
41     case AARCH64_TONEAREST:
42     default:
43       return FE_TONEAREST;
44   }
45 #else
46   return __aarch64_fe_default_rmode;
47 #endif
48 }
49 
50 int __fe_raise_inexact() {
51 #ifdef __ARM_FP
52   uint64_t fpsr;
53   __asm__ __volatile__("mrs  %0, fpsr" : "=r" (fpsr));
54   __asm__ __volatile__("msr  fpsr, %0" : : "ri" (fpsr | AARCH64_INEXACT));
55   return 0;
56 #else
57   return 0;
58 #endif
59 }
60