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
SkFloatToFixed_Check(float x)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
SkIntToFixed(int n)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
SkFixedRoundToFixed(SkFixed x)72 static inline SkFixed SkFixedRoundToFixed(SkFixed x) {
73 return (x + SK_FixedHalf) & 0xFFFF0000;
74 }
SkFixedCeilToFixed(SkFixed x)75 static inline SkFixed SkFixedCeilToFixed(SkFixed x) {
76 return (x + SK_Fixed1 - 1) & 0xFFFF0000;
77 }
SkFixedFloorToFixed(SkFixed x)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
SkFixedMul_longlong(SkFixed a,SkFixed b)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 */
SkFloatToFixed_arm(float x)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 }
SkFixedMul_arm(SkFixed x,SkFixed y)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