sqrt.c

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#include "libm.h"
#include "libm_util.h"
 
#if USE_SOFTWARE_SQRT
#define USE_SQRT_AMD_INLINE
#endif
#define USE_NAN_WITH_FLAGS
#define USE_HANDLE_ERROR
#include "libm_inlines.h"
#if USE_SOFTWARE_SQRT
#undef USE_SQRT_AMD_INLINE
#endif
#undef USE_NAN_WITH_FLAGS
#undef USE_HANDLE_ERROR
 
#include "libm_errno.h"
 
#pragma function(sqrt)
 
double sqrt(double x)
{
#if USE_SOFTWARE_SQRT
  return sqrt_amd_inline(x);
#else
  double r;
  unsigned long long ux;
  GET_BITS_DP64(x, ux);
 
  /* Check for special cases for Microsoft error handling */
  if ((ux & PINFBITPATT_DP64) == PINFBITPATT_DP64)
    {
      /* x is infinity, or NaN */
      if (ux & MANTBITS_DP64)
        {
          /* NaN  of some sort */
          /* If it's a signaling NaN, convert to QNaN */
          return _handle_error("sqrt", OP_SQRT, ux|0x0008000000000000, 
                                  _DOMAIN, 0,EDOM, x, 0.0, 1);
        }
      else
        {
          /* +/-infinity  */
          if (ux & SIGNBIT_DP64)
            {
              /* - infinity */
                return _handle_error("sqrt", OP_SQRT, INDEFBITPATT_DP64, 
                                    _DOMAIN, AMD_F_INVALID, EDOM, x, 0.0, 1);
            }
          /* positive infinite is not a problem */
        }
    }
  if ((ux & SIGNBIT_DP64)&&(ux & ~SIGNBIT_DP64))   /* if x < zero */
    {
        return _handle_error("sqrt", OP_SQRT, INDEFBITPATT_DP64, 
                            _DOMAIN, AMD_F_INVALID, EDOM, x, 0.0, 1);
    }
 
      /* VC++ intrinsic call */
  _mm_store_sd(&r, _mm_sqrt_sd(_mm_setzero_pd(), _mm_load_sd(&x)));
  return r;
#endif
}