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 "SkTypes.h"
12
13/** \file SkFixed.h
14
15    Types and macros for 16.16 fixed point
16*/
17
18/** 32 bit signed integer used to represent fractions values with 16 bits to the right of the decimal point
19*/
20typedef int32_t             SkFixed;
21#define SK_Fixed1           (1 << 16)
22#define SK_FixedHalf        (1 << 15)
23#define SK_FixedMax         (0x7FFFFFFF)
24#define SK_FixedMin         (-SK_FixedMax)
25#define SK_FixedNaN         ((int) 0x80000000)
26#define SK_FixedPI          (0x3243F)
27#define SK_FixedSqrt2       (92682)
28#define SK_FixedTanPIOver8  (0x6A0A)
29#define SK_FixedRoot2Over2  (0xB505)
30
31#define SkFixedToFloat(x)   ((x) * 1.5258789e-5f)
32#if 1
33    #define SkFloatToFixed(x)   ((SkFixed)((x) * SK_Fixed1))
34#else
35    // pins over/under flows to max/min int32 (slower than just a cast)
36    static inline SkFixed SkFloatToFixed(float x) {
37        int64_t n = x * SK_Fixed1;
38        return (SkFixed)n;
39    }
40#endif
41
42#ifdef SK_DEBUG
43    static inline SkFixed SkFloatToFixed_Check(float x) {
44        int64_t n64 = (int64_t)(x * SK_Fixed1);
45        SkFixed n32 = (SkFixed)n64;
46        SkASSERT(n64 == n32);
47        return n32;
48    }
49#else
50    #define SkFloatToFixed_Check(x) SkFloatToFixed(x)
51#endif
52
53#define SkFixedToDouble(x)  ((x) * 1.5258789e-5)
54#define SkDoubleToFixed(x)  ((SkFixed)((x) * SK_Fixed1))
55
56/** Converts an integer to a SkFixed, asserting that the result does not overflow
57    a 32 bit signed integer
58*/
59#ifdef SK_DEBUG
60    inline SkFixed SkIntToFixed(int n)
61    {
62        SkASSERT(n >= -32768 && n <= 32767);
63        return n << 16;
64    }
65#else
66    //  force the cast to SkFixed to ensure that the answer is signed (like the debug version)
67    #define SkIntToFixed(n)     (SkFixed)((n) << 16)
68#endif
69
70#define SkFixedRoundToInt(x)    (((x) + SK_FixedHalf) >> 16)
71#define SkFixedCeilToInt(x)     (((x) + SK_Fixed1 - 1) >> 16)
72#define SkFixedFloorToInt(x)    ((x) >> 16)
73
74#define SkFixedRoundToFixed(x)  (((x) + SK_FixedHalf) & 0xFFFF0000)
75#define SkFixedCeilToFixed(x)   (((x) + SK_Fixed1 - 1) & 0xFFFF0000)
76#define SkFixedFloorToFixed(x)  ((x) & 0xFFFF0000)
77
78#define SkFixedAbs(x)       SkAbs32(x)
79#define SkFixedAve(a, b)    (((a) + (b)) >> 1)
80
81SkFixed SkFixedMul_portable(SkFixed, SkFixed);
82
83#define SkFixedDiv(numer, denom)    SkDivBits(numer, denom, 16)
84
85///////////////////////////////////////////////////////////////////////////////
86// TODO: move fixed sin/cos into SkCosineMapper, as that is the only caller
87//       or rewrite SkCosineMapper to not use it at all
88
89SkFixed SkFixedSinCos(SkFixed radians, SkFixed* cosValueOrNull);
90#define SkFixedSin(radians)         SkFixedSinCos(radians, NULL)
91static inline SkFixed SkFixedCos(SkFixed radians) {
92    SkFixed cosValue;
93    (void)SkFixedSinCos(radians, &cosValue);
94    return cosValue;
95}
96
97//////////////////////////////////////////////////////////////////////////////////////////////////////
98// Now look for ASM overrides for our portable versions (should consider putting this in its own file)
99
100#ifdef SkLONGLONG
101    inline SkFixed SkFixedMul_longlong(SkFixed a, SkFixed b)
102    {
103        return (SkFixed)((int64_t)a * b >> 16);
104    }
105    #define SkFixedMul(a,b)     SkFixedMul_longlong(a,b)
106#endif
107
108#if defined(SK_CPU_ARM32)
109    /* This guy does not handle NaN or other obscurities, but is faster than
110       than (int)(x*65536).  When built on Android with -Os, needs forcing
111       to inline or we lose the speed benefit.
112    */
113    SK_ALWAYS_INLINE SkFixed SkFloatToFixed_arm(float x)
114    {
115        int32_t y, z;
116        asm("movs    %1, %3, lsl #1         \n"
117            "mov     %2, #0x8E              \n"
118            "sub     %1, %2, %1, lsr #24    \n"
119            "mov     %2, %3, lsl #8         \n"
120            "orr     %2, %2, #0x80000000    \n"
121            "mov     %1, %2, lsr %1         \n"
122            "it cs                          \n"
123            "rsbcs   %1, %1, #0             \n"
124            : "=r"(x), "=&r"(y), "=&r"(z)
125            : "r"(x)
126            : "cc"
127            );
128        return y;
129    }
130    inline SkFixed SkFixedMul_arm(SkFixed x, SkFixed y)
131    {
132        int32_t t;
133        asm("smull  %0, %2, %1, %3          \n"
134            "mov    %0, %0, lsr #16         \n"
135            "orr    %0, %0, %2, lsl #16     \n"
136            : "=r"(x), "=&r"(y), "=r"(t)
137            : "r"(x), "1"(y)
138            :
139            );
140        return x;
141    }
142    #undef SkFixedMul
143    #define SkFixedMul(x, y)        SkFixedMul_arm(x, y)
144
145    #undef SkFloatToFixed
146    #define SkFloatToFixed(x)  SkFloatToFixed_arm(x)
147#endif
148
149#ifndef SkFixedMul
150    #define SkFixedMul(x, y)    SkFixedMul_portable(x, y)
151#endif
152
153///////////////////////////////////////////////////////////////////////////////
154
155typedef int64_t SkFixed48;
156
157#define SkIntToFixed48(x)       ((SkFixed48)(x) << 48)
158#define SkFixed48ToInt(x)       ((int)((x) >> 48))
159#define SkFixedToFixed48(x)     ((SkFixed48)(x) << 32)
160#define SkFixed48ToFixed(x)     ((SkFixed)((x) >> 32))
161#define SkFloatToFixed48(x)     ((SkFixed48)((x) * (65536.0f * 65536.0f * 65536.0f)))
162
163#define SkScalarToFixed48(x)    SkFloatToFixed48(x)
164
165#endif
166