3d5a6b5f25
Bug: skia: Change-Id: I157f8c047145874c4585ae870018163908389b26 Reviewed-on: https://skia-review.googlesource.com/102321 Reviewed-by: Mike Klein <mtklein@google.com> Reviewed-by: Florin Malita <fmalita@chromium.org>
140 lines
4.8 KiB
C
140 lines
4.8 KiB
C
/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkFixed_DEFINED
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#define SkFixed_DEFINED
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#include "SkScalar.h"
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#include "SkSafe_math.h"
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#include "SkTypes.h"
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/** \file SkFixed.h
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Types and macros for 16.16 fixed point
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*/
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/** 32 bit signed integer used to represent fractions values with 16 bits to the right of the decimal point
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*/
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typedef int32_t SkFixed;
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#define SK_Fixed1 (1 << 16)
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#define SK_FixedHalf (1 << 15)
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#define SK_FixedMax (0x7FFFFFFF)
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#define SK_FixedMin (-SK_FixedMax)
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#define SK_FixedPI (0x3243F)
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#define SK_FixedSqrt2 (92682)
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#define SK_FixedTanPIOver8 (0x6A0A)
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#define SK_FixedRoot2Over2 (0xB505)
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// NOTE: SkFixedToFloat is exact. SkFloatToFixed seems to lack a rounding step. For all fixed-point
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// values, this version is as accurate as possible for (fixed -> float -> fixed). Rounding reduces
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// accuracy if the intermediate floats are in the range that only holds integers (adding 0.5f to an
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// odd integer then snaps to nearest even). Using double for the rounding math gives maximum
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// accuracy for (float -> fixed -> float), but that's usually overkill.
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#define SkFixedToFloat(x) ((x) * 1.52587890625e-5f)
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#define SkFloatToFixed(x) sk_float_saturate2int((x) * SK_Fixed1)
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#ifdef SK_DEBUG
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static inline SkFixed SkFloatToFixed_Check(float x) {
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int64_t n64 = (int64_t)(x * SK_Fixed1);
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SkFixed n32 = (SkFixed)n64;
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SkASSERT(n64 == n32);
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return n32;
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}
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#else
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#define SkFloatToFixed_Check(x) SkFloatToFixed(x)
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#endif
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#define SkFixedToDouble(x) ((x) * 1.52587890625e-5)
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#define SkDoubleToFixed(x) ((SkFixed)((x) * SK_Fixed1))
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/** Converts an integer to a SkFixed, asserting that the result does not overflow
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a 32 bit signed integer
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*/
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#ifdef SK_DEBUG
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inline SkFixed SkIntToFixed(int n)
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{
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SkASSERT(n >= -32768 && n <= 32767);
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// Left shifting a negative value has undefined behavior in C, so we cast to unsigned before
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// shifting.
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return (unsigned)n << 16;
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}
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#else
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// Left shifting a negative value has undefined behavior in C, so we cast to unsigned before
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// shifting. Then we force the cast to SkFixed to ensure that the answer is signed (like the
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// debug version).
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#define SkIntToFixed(n) (SkFixed)((unsigned)(n) << 16)
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#endif
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#define SkFixedRoundToInt(x) (((x) + SK_FixedHalf) >> 16)
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#define SkFixedCeilToInt(x) (((x) + SK_Fixed1 - 1) >> 16)
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#define SkFixedFloorToInt(x) ((x) >> 16)
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static inline SkFixed SkFixedRoundToFixed(SkFixed x) {
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return (x + SK_FixedHalf) & 0xFFFF0000;
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}
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static inline SkFixed SkFixedCeilToFixed(SkFixed x) {
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return (x + SK_Fixed1 - 1) & 0xFFFF0000;
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}
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static inline SkFixed SkFixedFloorToFixed(SkFixed x) {
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return x & 0xFFFF0000;
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}
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#define SkFixedAbs(x) SkAbs32(x)
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#define SkFixedAve(a, b) (((a) + (b)) >> 1)
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// The divide may exceed 32 bits. Clamp to a signed 32 bit result.
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#define SkFixedDiv(numer, denom) \
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SkToS32(SkTPin<int64_t>((SkLeftShift((int64_t)(numer), 16) / (denom)), SK_MinS32, SK_MaxS32))
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static inline SkFixed SkFixedMul(SkFixed a, SkFixed b) {
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return (SkFixed)((int64_t)a * b >> 16);
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}
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///////////////////////////////////////////////////////////////////////////////
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// Platform-specific alternatives to our portable versions.
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// The VCVT float-to-fixed instruction is part of the VFPv3 instruction set.
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#if defined(__ARM_VFPV3__)
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/* This guy does not handle NaN or other obscurities, but is faster than
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than (int)(x*65536). When built on Android with -Os, needs forcing
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to inline or we lose the speed benefit.
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*/
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SK_ALWAYS_INLINE SkFixed SkFloatToFixed_arm(float x)
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{
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int32_t y;
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asm("vcvt.s32.f32 %0, %0, #16": "+w"(x));
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memcpy(&y, &x, sizeof(y));
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return y;
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}
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#undef SkFloatToFixed
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#define SkFloatToFixed(x) SkFloatToFixed_arm(x)
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#endif
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///////////////////////////////////////////////////////////////////////////////
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#define SkFixedToScalar(x) SkFixedToFloat(x)
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#define SkScalarToFixed(x) SkFloatToFixed(x)
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///////////////////////////////////////////////////////////////////////////////
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typedef int64_t SkFixed3232; // 32.32
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#define SkFixed3232Max SK_MaxS64
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#define SkFixed3232Min (-SkFixed3232Max)
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#define SkIntToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 32))
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#define SkFixed3232ToInt(x) ((int)((x) >> 32))
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#define SkFixedToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 16))
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#define SkFixed3232ToFixed(x) ((SkFixed)((x) >> 16))
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#define SkFloatToFixed3232(x) sk_float_saturate2int64((x) * (65536.0f * 65536.0f))
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#define SkFixed3232ToFloat(x) (x * (1 / (65536.0f * 65536.0f)))
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#define SkScalarToFixed3232(x) SkFloatToFixed3232(x)
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#endif
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