| /* |
| * 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/core/SkScalar.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/SkSafe_math.h" |
| #include "include/private/SkTPin.h" |
| #include "include/private/SkTo.h" |
| |
| /** \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 SkFixedAbs(x) SkAbs32(x) |
| #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__) |
| /* 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)); |
| 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 |