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1 | |
2 /* | 1 /* |
3 * Copyright 2008 The Android Open Source Project | 2 * Copyright 2008 The Android Open Source Project |
4 * | 3 * |
5 * Use of this source code is governed by a BSD-style license that can be | 4 * Use of this source code is governed by a BSD-style license that can be |
6 * found in the LICENSE file. | 5 * found in the LICENSE file. |
7 */ | 6 */ |
8 | 7 |
9 | 8 |
10 #ifndef SkFloatBits_DEFINED | 9 #ifndef SkFloatBits_DEFINED |
11 #define SkFloatBits_DEFINED | 10 #define SkFloatBits_DEFINED |
12 | 11 |
13 #include "SkTypes.h" | 12 #include "SkTypes.h" |
| 13 #include <math.h> |
14 | 14 |
15 /** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement | 15 /** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement |
16 int. This also converts -0 (0x80000000) to 0. Doing this to a float allows | 16 int. This also converts -0 (0x80000000) to 0. Doing this to a float allows |
17 it to be compared using normal C operators (<, <=, etc.) | 17 it to be compared using normal C operators (<, <=, etc.) |
18 */ | 18 */ |
19 static inline int32_t SkSignBitTo2sCompliment(int32_t x) { | 19 static inline int32_t SkSignBitTo2sCompliment(int32_t x) { |
20 if (x < 0) { | 20 if (x < 0) { |
21 x &= 0x7FFFFFFF; | 21 x &= 0x7FFFFFFF; |
22 x = -x; | 22 x = -x; |
23 } | 23 } |
24 return x; | 24 return x; |
25 } | 25 } |
26 | 26 |
27 /** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float). | 27 /** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float). |
28 This undoes the result of SkSignBitTo2sCompliment(). | 28 This undoes the result of SkSignBitTo2sCompliment(). |
29 */ | 29 */ |
30 static inline int32_t Sk2sComplimentToSignBit(int32_t x) { | 30 static inline int32_t Sk2sComplimentToSignBit(int32_t x) { |
31 int sign = x >> 31; | 31 int sign = x >> 31; |
32 // make x positive | 32 // make x positive |
33 x = (x ^ sign) - sign; | 33 x = (x ^ sign) - sign; |
34 // set the sign bit as needed | 34 // set the sign bit as needed |
35 x |= SkLeftShift(sign, 31); | 35 x |= SkLeftShift(sign, 31); |
36 return x; | 36 return x; |
37 } | 37 } |
38 | 38 |
39 /** Given the bit representation of a float, return its value cast to an int. | |
40 If the value is out of range, or NaN, return return +/- SK_MaxS32 | |
41 */ | |
42 int32_t SkFloatBits_toIntCast(int32_t floatBits); | |
43 | |
44 /** Given the bit representation of a float, return its floor as an int. | |
45 If the value is out of range, or NaN, return return +/- SK_MaxS32 | |
46 */ | |
47 SK_API int32_t SkFloatBits_toIntFloor(int32_t floatBits); | |
48 | |
49 /** Given the bit representation of a float, return it rounded to an int. | |
50 If the value is out of range, or NaN, return return +/- SK_MaxS32 | |
51 */ | |
52 SK_API int32_t SkFloatBits_toIntRound(int32_t floatBits); | |
53 | |
54 /** Given the bit representation of a float, return its ceiling as an int. | |
55 If the value is out of range, or NaN, return return +/- SK_MaxS32 | |
56 */ | |
57 SK_API int32_t SkFloatBits_toIntCeil(int32_t floatBits); | |
58 | |
59 | |
60 union SkFloatIntUnion { | 39 union SkFloatIntUnion { |
61 float fFloat; | 40 float fFloat; |
62 int32_t fSignBitInt; | 41 int32_t fSignBitInt; |
63 }; | 42 }; |
64 | 43 |
65 // Helper to see a float as its bit pattern (w/o aliasing warnings) | 44 // Helper to see a float as its bit pattern (w/o aliasing warnings) |
66 static inline int32_t SkFloat2Bits(float x) { | 45 static inline int32_t SkFloat2Bits(float x) { |
67 SkFloatIntUnion data; | 46 SkFloatIntUnion data; |
68 data.fFloat = x; | 47 data.fFloat = x; |
69 return data.fSignBitInt; | 48 return data.fSignBitInt; |
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85 return SkSignBitTo2sCompliment(SkFloat2Bits(x)); | 64 return SkSignBitTo2sCompliment(SkFloat2Bits(x)); |
86 } | 65 } |
87 | 66 |
88 /** Return the 2s compliment int as a float. This undos the result of | 67 /** Return the 2s compliment int as a float. This undos the result of |
89 SkFloatAs2sCompliment | 68 SkFloatAs2sCompliment |
90 */ | 69 */ |
91 static inline float Sk2sComplimentAsFloat(int32_t x) { | 70 static inline float Sk2sComplimentAsFloat(int32_t x) { |
92 return SkBits2Float(Sk2sComplimentToSignBit(x)); | 71 return SkBits2Float(Sk2sComplimentToSignBit(x)); |
93 } | 72 } |
94 | 73 |
95 /** Return x cast to a float (i.e. (float)x) | 74 static inline int32_t pin_double_to_int(double x) { |
96 */ | 75 return (int32_t)SkTPin<double>(x, SK_MinS32, SK_MaxS32); |
97 float SkIntToFloatCast(int x); | |
98 | |
99 /** Return the float cast to an int. | |
100 If the value is out of range, or NaN, return +/- SK_MaxS32 | |
101 */ | |
102 static inline int32_t SkFloatToIntCast(float x) { | |
103 return SkFloatBits_toIntCast(SkFloat2Bits(x)); | |
104 } | 76 } |
105 | 77 |
106 /** Return the floor of the float as an int. | 78 /** Return the floor of the float as an int. |
107 If the value is out of range, or NaN, return +/- SK_MaxS32 | 79 If the value is out of range, or NaN, return +/- SK_MaxS32 |
108 */ | 80 */ |
109 static inline int32_t SkFloatToIntFloor(float x) { | 81 static inline int32_t SkFloatToIntFloor(float x) { |
110 return SkFloatBits_toIntFloor(SkFloat2Bits(x)); | 82 return pin_double_to_int(floor(x)); |
111 } | 83 } |
112 | 84 |
113 /** Return the float rounded to an int. | 85 /** Return the float rounded to an int. |
114 If the value is out of range, or NaN, return +/- SK_MaxS32 | 86 If the value is out of range, or NaN, return +/- SK_MaxS32 |
115 */ | 87 */ |
116 static inline int32_t SkFloatToIntRound(float x) { | 88 static inline int32_t SkFloatToIntRound(float x) { |
117 return SkFloatBits_toIntRound(SkFloat2Bits(x)); | 89 return pin_double_to_int(floor((double)x + 0.5)); |
118 } | 90 } |
119 | 91 |
120 /** Return the ceiling of the float as an int. | 92 /** Return the ceiling of the float as an int. |
121 If the value is out of range, or NaN, return +/- SK_MaxS32 | 93 If the value is out of range, or NaN, return +/- SK_MaxS32 |
122 */ | 94 */ |
123 static inline int32_t SkFloatToIntCeil(float x) { | 95 static inline int32_t SkFloatToIntCeil(float x) { |
124 return SkFloatBits_toIntCeil(SkFloat2Bits(x)); | 96 return pin_double_to_int(ceil(x)); |
125 } | 97 } |
126 | 98 |
127 // Scalar wrappers for float-bit routines | 99 // Scalar wrappers for float-bit routines |
128 | 100 |
129 #define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x) | 101 #define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x) |
130 #define Sk2sComplimentAsScalar(x) Sk2sComplimentAsFloat(x) | 102 #define Sk2sComplimentAsScalar(x) Sk2sComplimentAsFloat(x) |
131 | 103 |
132 #endif | 104 #endif |
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