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Diffstat (limited to '')
| -rw-r--r-- | gfx/skia/skia/include/private/base/SkFixed.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/gfx/skia/skia/include/private/base/SkFixed.h b/gfx/skia/skia/include/private/base/SkFixed.h new file mode 100644 index 0000000000..2c8f2fb56c --- /dev/null +++ b/gfx/skia/skia/include/private/base/SkFixed.h @@ -0,0 +1,143 @@ +/* + * 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 SkFixed_DEFINED +#define SkFixed_DEFINED + +#include "include/private/base/SkAssert.h" +#include "include/private/base/SkDebug.h" +#include "include/private/base/SkMath.h" // IWYU pragma: keep +#include "include/private/base/SkTPin.h" // IWYU pragma: keep + +#include <cstdint> + +/** \file SkFixed.h + + Types and macros for 16.16 fixed point +*/ + +/** 32 bit signed integer used to represent fractions values with 16 bits to the right of the decimal point +*/ +typedef int32_t SkFixed; +#define SK_Fixed1 (1 << 16) +#define SK_FixedHalf (1 << 15) +#define SK_FixedQuarter (1 << 14) +#define SK_FixedMax (0x7FFFFFFF) +#define SK_FixedMin (-SK_FixedMax) +#define SK_FixedPI (0x3243F) +#define SK_FixedSqrt2 (92682) +#define SK_FixedTanPIOver8 (0x6A0A) +#define SK_FixedRoot2Over2 (0xB505) + +// NOTE: SkFixedToFloat is exact. SkFloatToFixed seems to lack a rounding step. For all fixed-point +// values, this version is as accurate as possible for (fixed -> float -> fixed). Rounding reduces +// accuracy if the intermediate floats are in the range that only holds integers (adding 0.5f to an +// odd integer then snaps to nearest even). Using double for the rounding math gives maximum +// accuracy for (float -> fixed -> float), but that's usually overkill. +#define SkFixedToFloat(x) ((x) * 1.52587890625e-5f) +#define SkFloatToFixed(x) sk_float_saturate2int((x) * SK_Fixed1) + +#ifdef SK_DEBUG + static inline SkFixed SkFloatToFixed_Check(float x) { + int64_t n64 = (int64_t)(x * SK_Fixed1); + SkFixed n32 = (SkFixed)n64; + SkASSERT(n64 == n32); + return n32; + } +#else + #define SkFloatToFixed_Check(x) SkFloatToFixed(x) +#endif + +#define SkFixedToDouble(x) ((x) * 1.52587890625e-5) +#define SkDoubleToFixed(x) ((SkFixed)((x) * SK_Fixed1)) + +/** Converts an integer to a SkFixed, asserting that the result does not overflow + a 32 bit signed integer +*/ +#ifdef SK_DEBUG + inline SkFixed SkIntToFixed(int n) + { + SkASSERT(n >= -32768 && n <= 32767); + // Left shifting a negative value has undefined behavior in C, so we cast to unsigned before + // shifting. + return (SkFixed)( (unsigned)n << 16 ); + } +#else + // Left shifting a negative value has undefined behavior in C, so we cast to unsigned before + // shifting. Then we force the cast to SkFixed to ensure that the answer is signed (like the + // debug version). + #define SkIntToFixed(n) (SkFixed)((unsigned)(n) << 16) +#endif + +#define SkFixedRoundToInt(x) (((x) + SK_FixedHalf) >> 16) +#define SkFixedCeilToInt(x) (((x) + SK_Fixed1 - 1) >> 16) +#define SkFixedFloorToInt(x) ((x) >> 16) + +static inline SkFixed SkFixedRoundToFixed(SkFixed x) { + return (SkFixed)( (uint32_t)(x + SK_FixedHalf) & 0xFFFF0000 ); +} +static inline SkFixed SkFixedCeilToFixed(SkFixed x) { + return (SkFixed)( (uint32_t)(x + SK_Fixed1 - 1) & 0xFFFF0000 ); +} +static inline SkFixed SkFixedFloorToFixed(SkFixed x) { + return (SkFixed)( (uint32_t)x & 0xFFFF0000 ); +} + +#define SkFixedAve(a, b) (((a) + (b)) >> 1) + +// The divide may exceed 32 bits. Clamp to a signed 32 bit result. +#define SkFixedDiv(numer, denom) \ + SkToS32(SkTPin<int64_t>((SkLeftShift((int64_t)(numer), 16) / (denom)), SK_MinS32, SK_MaxS32)) + +static inline SkFixed SkFixedMul(SkFixed a, SkFixed b) { + return (SkFixed)((int64_t)a * b >> 16); +} + +/////////////////////////////////////////////////////////////////////////////// +// Platform-specific alternatives to our portable versions. + +// The VCVT float-to-fixed instruction is part of the VFPv3 instruction set. +#if defined(__ARM_VFPV3__) + #include <cstring> + + /* This does not handle NaN or other obscurities, but is faster than + than (int)(x*65536). When built on Android with -Os, needs forcing + to inline or we lose the speed benefit. + */ + SK_ALWAYS_INLINE SkFixed SkFloatToFixed_arm(float x) + { + int32_t y; + asm("vcvt.s32.f32 %0, %0, #16": "+w"(x)); + std::memcpy(&y, &x, sizeof(y)); + return y; + } + #undef SkFloatToFixed + #define SkFloatToFixed(x) SkFloatToFixed_arm(x) +#endif + +/////////////////////////////////////////////////////////////////////////////// + +#define SkFixedToScalar(x) SkFixedToFloat(x) +#define SkScalarToFixed(x) SkFloatToFixed(x) + +/////////////////////////////////////////////////////////////////////////////// + +typedef int64_t SkFixed3232; // 32.32 + +#define SkFixed3232Max SK_MaxS64 +#define SkFixed3232Min (-SkFixed3232Max) + +#define SkIntToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 32)) +#define SkFixed3232ToInt(x) ((int)((x) >> 32)) +#define SkFixedToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 16)) +#define SkFixed3232ToFixed(x) ((SkFixed)((x) >> 16)) +#define SkFloatToFixed3232(x) sk_float_saturate2int64((x) * (65536.0f * 65536.0f)) +#define SkFixed3232ToFloat(x) (x * (1 / (65536.0f * 65536.0f))) + +#define SkScalarToFixed3232(x) SkFloatToFixed3232(x) + +#endif |