mingw-w64-crt/math/signbitf.c

/**
 * This file has no copyright assigned and is placed in the Public Domain.
 * This file is part of the w64 mingw-runtime package.
 * No warranty is given; refer to the file DISCLAIMER.PD within this package.
 */
#define __FP_SIGNBIT  0x0200
int __signbitf (float x);

int __signbitf (float x) {
  unsigned short sw;
  __asm__ __volatile__ ("fxam; fstsw %%ax;"
	   : "=a" (sw)
	   : "t" (x) );
  return (sw & __FP_SIGNBIT) != 0;
}
int __attribute__ ((alias ("__signbitf"))) signbitf (float);