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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkFloatingPoint_opts_DEFINED
#define SkFloatingPoint_opts_DEFINED
#include "SkFloatingPoint.h"
namespace SK_OPTS_NS {
#if defined(SK_ARM_HAS_NEON)
static float rsqrt(float x) {
return sk_float_rsqrt(x); // This sk_float_rsqrt copy will take the NEON compile-time path.
}
#else
static float rsqrt(float x) {
// Get initial estimate.
int i = *SkTCast<int*>(&x);
i = 0x5F1FFFF9 - (i>>1);
float estimate = *SkTCast<float*>(&i);
// One step of Newton's method to refine.
const float estimate_sq = estimate*estimate;
estimate *= 0.703952253f*(2.38924456f-x*estimate_sq);
return estimate;
}
#endif
} // namespace SK_OPTS_NS
#endif//SkFloatingPoint_opts_DEFINED
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