move some public headers into private

BUG=skia:

Review URL: https://codereview.chromium.org/1289483002

3 files changed, 461 insertions, 0 deletions

diff --git a/include/private/SkFloatBits.h b/include/private/SkFloatBits.h
new file mode 100644
index 0000000000..3ddb9ef564
--- /dev/null
+++ b/include/private/SkFloatBits.h
@@ -0,0 +1,132 @@
+
+/*
+ * Copyright 2008 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 SkFloatBits_DEFINED
+#define SkFloatBits_DEFINED
+
+#include "SkTypes.h"
+
+/** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement
+    int. This also converts -0 (0x80000000) to 0. Doing this to a float allows
+    it to be compared using normal C operators (<, <=, etc.)
+*/
+static inline int32_t SkSignBitTo2sCompliment(int32_t x) {
+    if (x < 0) {
+        x &= 0x7FFFFFFF;
+        x = -x;
+    }
+    return x;
+}
+
+/** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float).
+    This undoes the result of SkSignBitTo2sCompliment().
+ */
+static inline int32_t Sk2sComplimentToSignBit(int32_t x) {
+    int sign = x >> 31;
+    // make x positive
+    x = (x ^ sign) - sign;
+    // set the sign bit as needed
+    x |= sign << 31;
+    return x;
+}
+
+/** Given the bit representation of a float, return its value cast to an int.
+    If the value is out of range, or NaN, return return +/- SK_MaxS32
+*/
+int32_t SkFloatBits_toIntCast(int32_t floatBits);
+
+/** Given the bit representation of a float, return its floor as an int.
+    If the value is out of range, or NaN, return return +/- SK_MaxS32
+ */
+SK_API int32_t SkFloatBits_toIntFloor(int32_t floatBits);
+
+/** Given the bit representation of a float, return it rounded to an int.
+    If the value is out of range, or NaN, return return +/- SK_MaxS32
+ */
+SK_API int32_t SkFloatBits_toIntRound(int32_t floatBits);
+
+/** Given the bit representation of a float, return its ceiling as an int.
+    If the value is out of range, or NaN, return return +/- SK_MaxS32
+ */
+SK_API int32_t SkFloatBits_toIntCeil(int32_t floatBits);
+
+
+union SkFloatIntUnion {
+    float   fFloat;
+    int32_t fSignBitInt;
+};
+
+// Helper to see a float as its bit pattern (w/o aliasing warnings)
+static inline int32_t SkFloat2Bits(float x) {
+    SkFloatIntUnion data;
+    data.fFloat = x;
+    return data.fSignBitInt;
+}
+
+// Helper to see a bit pattern as a float (w/o aliasing warnings)
+static inline float SkBits2Float(int32_t floatAsBits) {
+    SkFloatIntUnion data;
+    data.fSignBitInt = floatAsBits;
+    return data.fFloat;
+}
+
+/** Return the float as a 2s compliment int. Just to be used to compare floats
+    to each other or against positive float-bit-constants (like 0). This does
+    not return the int equivalent of the float, just something cheaper for
+    compares-only.
+ */
+static inline int32_t SkFloatAs2sCompliment(float x) {
+    return SkSignBitTo2sCompliment(SkFloat2Bits(x));
+}
+
+/** Return the 2s compliment int as a float. This undos the result of
+    SkFloatAs2sCompliment
+ */
+static inline float Sk2sComplimentAsFloat(int32_t x) {
+    return SkBits2Float(Sk2sComplimentToSignBit(x));
+}
+
+/** Return x cast to a float (i.e. (float)x)
+*/
+float SkIntToFloatCast(int x);
+
+/** Return the float cast to an int.
+    If the value is out of range, or NaN, return +/- SK_MaxS32
+*/
+static inline int32_t SkFloatToIntCast(float x) {
+    return SkFloatBits_toIntCast(SkFloat2Bits(x));
+}
+
+/** Return the floor of the float as an int.
+    If the value is out of range, or NaN, return +/- SK_MaxS32
+*/
+static inline int32_t SkFloatToIntFloor(float x) {
+    return SkFloatBits_toIntFloor(SkFloat2Bits(x));
+}
+
+/** Return the float rounded to an int.
+    If the value is out of range, or NaN, return +/- SK_MaxS32
+*/
+static inline int32_t SkFloatToIntRound(float x) {
+    return SkFloatBits_toIntRound(SkFloat2Bits(x));
+}
+
+/** Return the ceiling of the float as an int.
+    If the value is out of range, or NaN, return +/- SK_MaxS32
+*/
+static inline int32_t SkFloatToIntCeil(float x) {
+    return SkFloatBits_toIntCeil(SkFloat2Bits(x));
+}
+
+//  Scalar wrappers for float-bit routines
+
+#define SkScalarAs2sCompliment(x)    SkFloatAs2sCompliment(x)
+#define Sk2sComplimentAsScalar(x)    Sk2sComplimentAsFloat(x)
+
+#endif
diff --git a/include/private/SkFloatingPoint.h b/include/private/SkFloatingPoint.h
new file mode 100644
index 0000000000..f7ee816b12
--- /dev/null
+++ b/include/private/SkFloatingPoint.h
@@ -0,0 +1,170 @@
+
+/*
+ * 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>
+
+// For _POSIX_VERSION
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+#include <unistd.h>
+#endif
+
+#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) {
+// c++11 contains a 'float copysign(float, float)' function in <cmath>.
+// clang-cl reports __cplusplus for clang, not the __cplusplus vc++ version _MSC_VER would report.
+#if (defined(_MSC_VER) && defined(__clang__))
+#    define SK_BUILD_WITH_CLANG_CL 1
+#else
+#    define SK_BUILD_WITH_CLANG_CL 0
+#endif
+#if (!SK_BUILD_WITH_CLANG_CL && __cplusplus >= 201103L) || (_MSC_VER >= 1800)
+    return copysignf(x, y);
+
+// Posix has demanded 'float copysignf(float, float)' (from C99) since Issue 6.
+#elif defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
+    return copysignf(x, y);
+
+// Visual studio prior to 13 only has 'double _copysign(double, double)'.
+#elif defined(_MSC_VER)
+    return (float)_copysign(x, y);
+
+// Otherwise convert to bits and extract sign.
+#else
+    int32_t xbits = SkFloat2Bits(x);
+    int32_t ybits = SkFloat2Bits(y);
+    return SkBits2Float((xbits & 0x7FFFFFFF) | (ybits & 0x80000000));
+#endif
+}
+
+#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)
+
+#define sk_float_round(x) sk_float_floor((x) + 0.5f)
+
+// can't find log2f on android, but maybe that just a tool bug?
+#ifdef SK_BUILD_FOR_ANDROID
+    static inline float sk_float_log2(float x) {
+        const double inv_ln_2 = 1.44269504088896;
+        return (float)(log(x) * inv_ln_2);
+    }
+#else
+    #define sk_float_log2(x)        log2f(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
+
+#define sk_double_floor(x)          floor(x)
+#define sk_double_round(x)          floor((x) + 0.5)
+#define sk_double_ceil(x)           ceil(x)
+#define sk_double_floor2int(x)      (int)floor(x)
+#define sk_double_round2int(x)      (int)floor((x) + 0.5f)
+#define sk_double_ceil2int(x)       (int)ceil(x)
+
+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))
+
+// We forward declare this to break an #include cycle.
+// (SkScalar -> SkFloatingPoint -> SkOpts.h -> SkXfermode -> SkColor -> SkScalar)
+namespace SkOpts { extern float (*rsqrt)(float); }
+
+// 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.
+//
+// Optimized constants in the null path courtesy of http://rrrola.wz.cz/inv_sqrt.html
+#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
+    return _mm_cvtss_f32(_mm_rsqrt_ss(_mm_set_ss(x)));
+#elif defined(SK_ARM_HAS_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
+    // Perhaps runtime-detected NEON, or a portable fallback.
+    return SkOpts::rsqrt(x);
+#endif
+}
+
+// This is the number of significant digits we can print in a string such that when we read that
+// string back we get the floating point number we expect.  The minimum value C requires is 6, but
+// most compilers support 9
+#ifdef FLT_DECIMAL_DIG
+#define SK_FLT_DECIMAL_DIG FLT_DECIMAL_DIG
+#else
+#define SK_FLT_DECIMAL_DIG 9
+#endif
+
+#endif
diff --git a/include/private/SkWeakRefCnt.h b/include/private/SkWeakRefCnt.h
new file mode 100644
index 0000000000..a550951970
--- /dev/null
+++ b/include/private/SkWeakRefCnt.h
@@ -0,0 +1,159 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkWeakRefCnt_DEFINED
+#define SkWeakRefCnt_DEFINED
+
+#include "SkRefCnt.h"
+#include "SkAtomics.h"
+
+/** \class SkWeakRefCnt
+
+    SkWeakRefCnt is the base class for objects that may be shared by multiple
+    objects. When an existing strong owner wants to share a reference, it calls
+    ref(). When a strong owner wants to release its reference, it calls
+    unref(). When the shared object's strong reference count goes to zero as
+    the result of an unref() call, its (virtual) weak_dispose method is called.
+    It is an error for the destructor to be called explicitly (or via the
+    object going out of scope on the stack or calling delete) if
+    getRefCnt() > 1.
+
+    In addition to strong ownership, an owner may instead obtain a weak
+    reference by calling weak_ref(). A call to weak_ref() must be balanced by a
+    call to weak_unref(). To obtain a strong reference from a weak reference,
+    call try_ref(). If try_ref() returns true, the owner's pointer is now also
+    a strong reference on which unref() must be called. Note that this does not
+    affect the original weak reference, weak_unref() must still be called. When
+    the weak reference count goes to zero, the object is deleted. While the
+    weak reference count is positive and the strong reference count is zero the
+    object still exists, but will be in the disposed state. It is up to the
+    object to define what this means.
+
+    Note that a strong reference implicitly implies a weak reference. As a
+    result, it is allowable for the owner of a strong ref to call try_ref().
+    This will have the same effect as calling ref(), but may be more expensive.
+
+    Example:
+
+    SkWeakRefCnt myRef = strongRef.weak_ref();
+    ... // strongRef.unref() may or may not be called
+    if (myRef.try_ref()) {
+        ... // use myRef
+        myRef.unref();
+    } else {
+        // myRef is in the disposed state
+    }
+    myRef.weak_unref();
+*/
+class SK_API SkWeakRefCnt : public SkRefCnt {
+public:
+    /** Default construct, initializing the reference counts to 1.
+        The strong references collectively hold one weak reference. When the
+        strong reference count goes to zero, the collectively held weak
+        reference is released.
+    */
+    SkWeakRefCnt() : SkRefCnt(), fWeakCnt(1) {}
+
+    /** Destruct, asserting that the weak reference count is 1.
+    */
+    virtual ~SkWeakRefCnt() {
+#ifdef SK_DEBUG
+        SkASSERT(fWeakCnt == 1);
+        fWeakCnt = 0;
+#endif
+    }
+
+    /** Return the weak reference count.
+    */
+    int32_t getWeakCnt() const { return fWeakCnt; }
+
+#ifdef SK_DEBUG
+    void validate() const {
+        this->INHERITED::validate();
+        SkASSERT(fWeakCnt > 0);
+    }
+#endif
+
+    /** Creates a strong reference from a weak reference, if possible. The
+        caller must already be an owner. If try_ref() returns true the owner
+        is in posession of an additional strong reference. Both the original
+        reference and new reference must be properly unreferenced. If try_ref()
+        returns false, no strong reference could be created and the owner's
+        reference is in the same state as before the call.
+    */
+    bool SK_WARN_UNUSED_RESULT try_ref() const {
+        if (sk_atomic_conditional_inc(&fRefCnt) != 0) {
+            // Acquire barrier (L/SL), if not provided above.
+            // Prevents subsequent code from happening before the increment.
+            sk_membar_acquire__after_atomic_conditional_inc();
+            return true;
+        }
+        return false;
+    }
+
+    /** Increment the weak reference count. Must be balanced by a call to
+        weak_unref().
+    */
+    void weak_ref() const {
+        SkASSERT(fRefCnt > 0);
+        SkASSERT(fWeakCnt > 0);
+        sk_atomic_inc(&fWeakCnt);  // No barrier required.
+    }
+
+    /** Decrement the weak reference count. If the weak reference count is 1
+        before the decrement, then call delete on the object. Note that if this
+        is the case, then the object needs to have been allocated via new, and
+        not on the stack.
+    */
+    void weak_unref() const {
+        SkASSERT(fWeakCnt > 0);
+        // Release barrier (SL/S), if not provided below.
+        if (sk_atomic_dec(&fWeakCnt) == 1) {
+            // Acquire barrier (L/SL), if not provided above.
+            // Prevents code in destructor from happening before the decrement.
+            sk_membar_acquire__after_atomic_dec();
+#ifdef SK_DEBUG
+            // so our destructor won't complain
+            fWeakCnt = 1;
+#endif
+            this->INHERITED::internal_dispose();
+        }
+    }
+
+    /** Returns true if there are no strong references to the object. When this
+        is the case all future calls to try_ref() will return false.
+    */
+    bool weak_expired() const {
+        return fRefCnt == 0;
+    }
+
+protected:
+    /** Called when the strong reference count goes to zero. This allows the
+        object to free any resources it may be holding. Weak references may
+        still exist and their level of allowed access to the object is defined
+        by the object's class.
+    */
+    virtual void weak_dispose() const {
+    }
+
+private:
+    /** Called when the strong reference count goes to zero. Calls weak_dispose
+        on the object and releases the implicit weak reference held
+        collectively by the strong references.
+    */
+    void internal_dispose() const override {
+        weak_dispose();
+        weak_unref();
+    }
+
+    /* Invariant: fWeakCnt = #weak + (fRefCnt > 0 ? 1 : 0) */
+    mutable int32_t fWeakCnt;
+
+    typedef SkRefCnt INHERITED;
+};
+
+#endif