1 //===----- lib/i386/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 "../fp_mode.h" 10 11 #define X87_TONEAREST 0x0000 12 #define X87_DOWNWARD 0x0400 13 #define X87_UPWARD 0x0800 14 #define X87_TOWARDZERO 0x0c00 15 #define X87_RMODE_MASK (X87_TONEAREST | X87_UPWARD | X87_DOWNWARD | X87_TOWARDZERO) 16 17 CRT_FE_ROUND_MODE __fe_getround(void) { 18 // Assume that the rounding mode state for the fpu agrees with the SSE unit. 19 unsigned short cw; 20 __asm__ __volatile__ ("fnstcw %0" : "=m" (cw)); 21 22 switch (cw & X87_RMODE_MASK) { 23 case X87_TONEAREST: 24 return CRT_FE_TONEAREST; 25 case X87_DOWNWARD: 26 return CRT_FE_DOWNWARD; 27 case X87_UPWARD: 28 return CRT_FE_UPWARD; 29 case X87_TOWARDZERO: 30 return CRT_FE_TOWARDZERO; 31 } 32 return CRT_FE_TONEAREST; 33 } 34 35 int __fe_raise_inexact(void) { 36 float f = 1.0f, g = 3.0f; 37 __asm__ __volatile__ ("fdivs %1" : "+t" (f) : "m" (g)); 38 return 0; 39 } 40