epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 1 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 2 | /* |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 3 | * Copyright 2008 The Android Open Source Project |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 4 | * |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 5 | * Use of this source code is governed by a BSD-style license that can be |
| 6 | * found in the LICENSE file. |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 7 | */ |
| 8 | |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 9 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 10 | #ifndef SkFloatBits_DEFINED |
| 11 | #define SkFloatBits_DEFINED |
| 12 | |
| 13 | #include "SkTypes.h" |
| 14 | |
| 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 |
| 17 | it to be compared using normal C operators (<, <=, etc.) |
| 18 | */ |
| 19 | static inline int32_t SkSignBitTo2sCompliment(int32_t x) { |
| 20 | if (x < 0) { |
| 21 | x &= 0x7FFFFFFF; |
| 22 | x = -x; |
| 23 | } |
| 24 | return x; |
| 25 | } |
| 26 | |
| 27 | /** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float). |
| 28 | This undoes the result of SkSignBitTo2sCompliment(). |
| 29 | */ |
| 30 | static inline int32_t Sk2sComplimentToSignBit(int32_t x) { |
| 31 | int sign = x >> 31; |
| 32 | // make x positive |
| 33 | x = (x ^ sign) - sign; |
| 34 | // set the sign bit as needed |
caryclark | 952538e | 2016-02-26 05:01:42 -0800 | [diff] [blame] | 35 | x |= SkLeftShift(sign, 31); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 36 | return x; |
| 37 | } |
| 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 | */ |
ctguil@chromium.org | 7ffb1b2 | 2011-03-15 21:27:08 +0000 | [diff] [blame] | 47 | SK_API int32_t SkFloatBits_toIntFloor(int32_t floatBits); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 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 | */ |
ctguil@chromium.org | 7ffb1b2 | 2011-03-15 21:27:08 +0000 | [diff] [blame] | 52 | SK_API int32_t SkFloatBits_toIntRound(int32_t floatBits); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 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 | */ |
ctguil@chromium.org | 7ffb1b2 | 2011-03-15 21:27:08 +0000 | [diff] [blame] | 57 | SK_API int32_t SkFloatBits_toIntCeil(int32_t floatBits); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 58 | |
| 59 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 60 | union SkFloatIntUnion { |
| 61 | float fFloat; |
| 62 | int32_t fSignBitInt; |
| 63 | }; |
| 64 | |
| 65 | // Helper to see a float as its bit pattern (w/o aliasing warnings) |
| 66 | static inline int32_t SkFloat2Bits(float x) { |
| 67 | SkFloatIntUnion data; |
| 68 | data.fFloat = x; |
| 69 | return data.fSignBitInt; |
| 70 | } |
| 71 | |
| 72 | // Helper to see a bit pattern as a float (w/o aliasing warnings) |
| 73 | static inline float SkBits2Float(int32_t floatAsBits) { |
| 74 | SkFloatIntUnion data; |
| 75 | data.fSignBitInt = floatAsBits; |
| 76 | return data.fFloat; |
| 77 | } |
| 78 | |
| 79 | /** Return the float as a 2s compliment int. Just to be used to compare floats |
| 80 | to each other or against positive float-bit-constants (like 0). This does |
| 81 | not return the int equivalent of the float, just something cheaper for |
| 82 | compares-only. |
| 83 | */ |
| 84 | static inline int32_t SkFloatAs2sCompliment(float x) { |
| 85 | return SkSignBitTo2sCompliment(SkFloat2Bits(x)); |
| 86 | } |
| 87 | |
| 88 | /** Return the 2s compliment int as a float. This undos the result of |
| 89 | SkFloatAs2sCompliment |
| 90 | */ |
| 91 | static inline float Sk2sComplimentAsFloat(int32_t x) { |
| 92 | return SkBits2Float(Sk2sComplimentToSignBit(x)); |
| 93 | } |
| 94 | |
| 95 | /** Return x cast to a float (i.e. (float)x) |
| 96 | */ |
| 97 | float SkIntToFloatCast(int x); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 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 | } |
| 105 | |
| 106 | /** Return the floor of the float as an int. |
| 107 | If the value is out of range, or NaN, return +/- SK_MaxS32 |
| 108 | */ |
| 109 | static inline int32_t SkFloatToIntFloor(float x) { |
| 110 | return SkFloatBits_toIntFloor(SkFloat2Bits(x)); |
| 111 | } |
| 112 | |
| 113 | /** Return the float rounded to an int. |
| 114 | If the value is out of range, or NaN, return +/- SK_MaxS32 |
| 115 | */ |
| 116 | static inline int32_t SkFloatToIntRound(float x) { |
| 117 | return SkFloatBits_toIntRound(SkFloat2Bits(x)); |
| 118 | } |
| 119 | |
| 120 | /** Return the ceiling of the float as an int. |
| 121 | If the value is out of range, or NaN, return +/- SK_MaxS32 |
| 122 | */ |
| 123 | static inline int32_t SkFloatToIntCeil(float x) { |
| 124 | return SkFloatBits_toIntCeil(SkFloat2Bits(x)); |
| 125 | } |
| 126 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 127 | // Scalar wrappers for float-bit routines |
| 128 | |
reed@google.com | 8f4d230 | 2013-12-17 16:44:46 +0000 | [diff] [blame] | 129 | #define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x) |
| 130 | #define Sk2sComplimentAsScalar(x) Sk2sComplimentAsFloat(x) |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 131 | |
| 132 | #endif |