compiler-rt/lib/builtins/arm/fp_mode.c

   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 }