40 lines · c
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-exception6//7//===----------------------------------------------------------------------===//8 9#include "../fp_mode.h"10 11#define X87_TONEAREST 0x000012#define X87_DOWNWARD 0x040013#define X87_UPWARD 0x080014#define X87_TOWARDZERO 0x0c0015#define X87_RMODE_MASK (X87_TONEAREST | X87_UPWARD | X87_DOWNWARD | X87_TOWARDZERO)16 17CRT_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 35int __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