1 /* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkFixed_DEFINED 9 #define SkFixed_DEFINED 10 11 #include "SkScalar.h" 12 #include "SkSafe_math.h" 13 14 #include "SkTypes.h" 15 16 /** \file SkFixed.h 17 18 Types and macros for 16.16 fixed point 19 */ 20 21 /** 32 bit signed integer used to represent fractions values with 16 bits to the right of the decimal point 22 */ 23 typedef int32_t SkFixed; 24 #define SK_Fixed1 (1 << 16) 25 #define SK_FixedHalf (1 << 15) 26 #define SK_FixedMax (0x7FFFFFFF) 27 #define SK_FixedMin (-SK_FixedMax) 28 #define SK_FixedPI (0x3243F) 29 #define SK_FixedSqrt2 (92682) 30 #define SK_FixedTanPIOver8 (0x6A0A) 31 #define SK_FixedRoot2Over2 (0xB505) 32 33 #define SkFixedToFloat(x) ((x) * 1.52587890625e-5f) 34 #define SkFloatToFixed(x) ((SkFixed)((x) * SK_Fixed1)) 35 36 #ifdef SK_DEBUG 37 static inline SkFixed SkFloatToFixed_Check(float x) { 38 int64_t n64 = (int64_t)(x * SK_Fixed1); 39 SkFixed n32 = (SkFixed)n64; 40 SkASSERT(n64 == n32); 41 return n32; 42 } 43 #else 44 #define SkFloatToFixed_Check(x) SkFloatToFixed(x) 45 #endif 46 47 #define SkFixedToDouble(x) ((x) * 1.52587890625e-5) 48 #define SkDoubleToFixed(x) ((SkFixed)((x) * SK_Fixed1)) 49 50 /** Converts an integer to a SkFixed, asserting that the result does not overflow 51 a 32 bit signed integer 52 */ 53 #ifdef SK_DEBUG 54 inline SkFixed SkIntToFixed(int n) 55 { 56 SkASSERT(n >= -32768 && n <= 32767); 57 // Left shifting a negative value has undefined behavior in C, so we cast to unsigned before 58 // shifting. 59 return (unsigned)n << 16; 60 } 61 #else 62 // Left shifting a negative value has undefined behavior in C, so we cast to unsigned before 63 // shifting. Then we force the cast to SkFixed to ensure that the answer is signed (like the 64 // debug version). 65 #define SkIntToFixed(n) (SkFixed)((unsigned)(n) << 16) 66 #endif 67 68 #define SkFixedRoundToInt(x) (((x) + SK_FixedHalf) >> 16) 69 #define SkFixedCeilToInt(x) (((x) + SK_Fixed1 - 1) >> 16) 70 #define SkFixedFloorToInt(x) ((x) >> 16) 71 72 static inline SkFixed SkFixedRoundToFixed(SkFixed x) { 73 return (x + SK_FixedHalf) & 0xFFFF0000; 74 } 75 static inline SkFixed SkFixedCeilToFixed(SkFixed x) { 76 return (x + SK_Fixed1 - 1) & 0xFFFF0000; 77 } 78 static inline SkFixed SkFixedFloorToFixed(SkFixed x) { 79 return x & 0xFFFF0000; 80 } 81 82 #define SkFixedAbs(x) SkAbs32(x) 83 #define SkFixedAve(a, b) (((a) + (b)) >> 1) 84 85 // The divide may exceed 32 bits. Clamp to a signed 32 bit result. 86 #define SkFixedDiv(numer, denom) \ 87 SkToS32(SkTPin<int64_t>((SkLeftShift((int64_t)(numer), 16) / (denom)), SK_MinS32, SK_MaxS32)) 88 89 ////////////////////////////////////////////////////////////////////////////////////////////////////// 90 // Now look for ASM overrides for our portable versions (should consider putting this in its own file) 91 92 inline SkFixed SkFixedMul_longlong(SkFixed a, SkFixed b) { 93 return (SkFixed)((int64_t)a * b >> 16); 94 } 95 #define SkFixedMul(a,b) SkFixedMul_longlong(a,b) 96 97 98 #if defined(SK_CPU_ARM32) 99 /* This guy does not handle NaN or other obscurities, but is faster than 100 than (int)(x*65536). When built on Android with -Os, needs forcing 101 to inline or we lose the speed benefit. 102 */ 103 SK_ALWAYS_INLINE SkFixed SkFloatToFixed_arm(float x) 104 { 105 int32_t y, z; 106 asm("movs %1, %3, lsl #1 \n" 107 "mov %2, #0x8E \n" 108 "sub %1, %2, %1, lsr #24 \n" 109 "mov %2, %3, lsl #8 \n" 110 "orr %2, %2, #0x80000000 \n" 111 "mov %1, %2, lsr %1 \n" 112 "it cs \n" 113 "rsbcs %1, %1, #0 \n" 114 : "=r"(x), "=&r"(y), "=&r"(z) 115 : "r"(x) 116 : "cc" 117 ); 118 return y; 119 } 120 inline SkFixed SkFixedMul_arm(SkFixed x, SkFixed y) 121 { 122 int32_t t; 123 asm("smull %0, %2, %1, %3 \n" 124 "mov %0, %0, lsr #16 \n" 125 "orr %0, %0, %2, lsl #16 \n" 126 : "=r"(x), "=&r"(y), "=r"(t) 127 : "r"(x), "1"(y) 128 : 129 ); 130 return x; 131 } 132 #undef SkFixedMul 133 #define SkFixedMul(x, y) SkFixedMul_arm(x, y) 134 135 #undef SkFloatToFixed 136 #define SkFloatToFixed(x) SkFloatToFixed_arm(x) 137 #endif 138 139 /////////////////////////////////////////////////////////////////////////////// 140 141 #define SkFixedToScalar(x) SkFixedToFloat(x) 142 #define SkScalarToFixed(x) SkFloatToFixed(x) 143 144 /////////////////////////////////////////////////////////////////////////////// 145 146 typedef int64_t SkFixed3232; // 32.32 147 148 #define SkFixed3232Max (0x7FFFFFFFFFFFFFFFLL) 149 #define SkFixed3232Min (-SkFixed3232Max) 150 151 #define SkIntToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 32)) 152 #define SkFixed3232ToInt(x) ((int)((x) >> 32)) 153 #define SkFixedToFixed3232(x) (SkLeftShift((SkFixed3232)(x), 16)) 154 #define SkFixed3232ToFixed(x) ((SkFixed)((x) >> 16)) 155 #define SkFloatToFixed3232(x) ((SkFixed3232)((x) * (65536.0f * 65536.0f))) 156 #define SkFixed3232ToFloat(x) (x * (1 / (65536.0f * 65536.0f))) 157 158 #define SkScalarToFixed3232(x) SkFloatToFixed3232(x) 159 160 #endif 161
