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 /*

  * Copyright 2006 The Android Open Source Project

  *

  * Use of this source code is governed by a BSD-style license that can be

  * found in the LICENSE file.

  */

 #ifndef SkFloatingPoint_DEFINED

 #define SkFloatingPoint_DEFINED

 #include "SkTypes.h"

 #include <math.h>

 #include <float.h>

 #include "SkFloatBits.h"

 // C++98 cmath std::pow seems to be the earliest portable way to get float pow.

 // However, on Linux including cmath undefines isfinite.

 // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14608

 static inline float sk_float_pow(float base, float exp) {

     return powf(base, exp);

 }

 static inline float sk_float_copysign(float x, float y) {

     int32_t xbits = SkFloat2Bits(x);

     int32_t ybits = SkFloat2Bits(y);

     return SkBits2Float((xbits & 0x7FFFFFFF) | (ybits & 0x80000000));

 }

 #ifdef SK_BUILD_FOR_WINCE

     #define sk_float_sqrt(x)        (float)::sqrt(x)

     #define sk_float_sin(x)         (float)::sin(x)

     #define sk_float_cos(x)         (float)::cos(x)

     #define sk_float_tan(x)         (float)::tan(x)

     #define sk_float_acos(x)        (float)::acos(x)

     #define sk_float_asin(x)        (float)::asin(x)

     #define sk_float_atan2(y,x)     (float)::atan2(y,x)

     #define sk_float_abs(x)         (float)::fabs(x)

     #define sk_float_mod(x,y)       (float)::fmod(x,y)

     #define sk_float_exp(x)         (float)::exp(x)

     #define sk_float_log(x)         (float)::log(x)

     #define sk_float_floor(x)       (float)::floor(x)

     #define sk_float_ceil(x)        (float)::ceil(x)

 #else

     #define sk_float_sqrt(x)        sqrtf(x)

     #define sk_float_sin(x)         sinf(x)

     #define sk_float_cos(x)         cosf(x)

     #define sk_float_tan(x)         tanf(x)

     #define sk_float_floor(x)       floorf(x)

     #define sk_float_ceil(x)        ceilf(x)

 #ifdef SK_BUILD_FOR_MAC

     #define sk_float_acos(x)        static_cast<float>(acos(x))

     #define sk_float_asin(x)        static_cast<float>(asin(x))

 #else

     #define sk_float_acos(x)        acosf(x)

     #define sk_float_asin(x)        asinf(x)

 #endif

     #define sk_float_atan2(y,x)     atan2f(y,x)

     #define sk_float_abs(x)         fabsf(x)

     #define sk_float_mod(x,y)       fmodf(x,y)

     #define sk_float_exp(x)         expf(x)

     #define sk_float_log(x)         logf(x)

 #endif

 #ifdef SK_BUILD_FOR_WIN

     #define sk_float_isfinite(x)    _finite(x)

     #define sk_float_isnan(x)       _isnan(x)

     static inline int sk_float_isinf(float x) {

         int32_t bits = SkFloat2Bits(x);

         return (bits << 1) == (0xFF << 24);

     }

 #else

     #define sk_float_isfinite(x)    isfinite(x)

     #define sk_float_isnan(x)       isnan(x)

     #define sk_float_isinf(x)       isinf(x)

 #endif

 #define sk_double_isnan(a)          sk_float_isnan(a)

 #ifdef SK_USE_FLOATBITS

     #define sk_float_floor2int(x)   SkFloatToIntFloor(x)

     #define sk_float_round2int(x)   SkFloatToIntRound(x)

     #define sk_float_ceil2int(x)    SkFloatToIntCeil(x)

 #else

     #define sk_float_floor2int(x)   (int)sk_float_floor(x)

     #define sk_float_round2int(x)   (int)sk_float_floor((x) + 0.5f)

     #define sk_float_ceil2int(x)    (int)sk_float_ceil(x)

 #endif

 extern const uint32_t gIEEENotANumber;

 extern const uint32_t gIEEEInfinity;

 extern const uint32_t gIEEENegativeInfinity;

 #define SK_FloatNaN                 (*SkTCast<const float*>(&gIEEENotANumber))

 #define SK_FloatInfinity            (*SkTCast<const float*>(&gIEEEInfinity))

 #define SK_FloatNegativeInfinity    (*SkTCast<const float*>(&gIEEENegativeInfinity))

 #if defined(__SSE__)

 #include <xmmintrin.h>

 #elif defined(__ARM_NEON__)

 #include <arm_neon.h>

 #endif

 // Fast, approximate inverse square root.

 // Compare to name-brand "1.0f / sk_float_sqrt(x)".  Should be around 10x faster on SSE, 2x on NEON.

 static inline float sk_float_rsqrt(const float x) {

 // We want all this inlined, so we'll inline SIMD and just take the hit when we don't know we've got

 // it at compile time.  This is going to be too fast to productively hide behind a function pointer.

 //

 // We do one step of Newton's method to refine the estimates in the NEON and null paths.  No

 // refinement is faster, but very innacurate.  Two steps is more accurate, but slower than 1/sqrt.

 #if defined(__SSE__)

     float result;

     _mm_store_ss(&result, _mm_rsqrt_ss(_mm_set_ss(x)));

     return result;

 #elif defined(__ARM_NEON__)

     // Get initial estimate.

     const float32x2_t xx = vdup_n_f32(x);  // Clever readers will note we're doing everything 2x.

     float32x2_t estimate = vrsqrte_f32(xx);

     // One step of Newton's method to refine.

     const float32x2_t estimate_sq = vmul_f32(estimate, estimate);

     estimate = vmul_f32(estimate, vrsqrts_f32(xx, estimate_sq));

     return vget_lane_f32(estimate, 0);  // 1 will work fine too; the answer's in both places.

 #else

     // Get initial estimate.

     int i = *SkTCast<int*>(&x);

     i = 0x5f3759df - (i>>1);

     float estimate = *SkTCast<float*>(&i);

     // One step of Newton's method to refine.

     const float estimate_sq = estimate*estimate;

     estimate *= (1.5f-0.5f*x*estimate_sq);

     return estimate;

 #endif

 }

 #endif