reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef Sk64_DEFINED |
| 18 | #define Sk64_DEFINED |
| 19 | |
| 20 | #include "SkFixed.h" |
| 21 | #include "SkMath.h" |
| 22 | |
| 23 | /** \class Sk64 |
| 24 | |
| 25 | Sk64 is a 64-bit math package that does not require long long support from the compiler. |
| 26 | */ |
| 27 | struct Sk64 { |
| 28 | int32_t fHi; //!< the high 32 bits of the number (including sign) |
| 29 | uint32_t fLo; //!< the low 32 bits of the number |
| 30 | |
| 31 | /** Returns non-zero if the Sk64 can be represented as a signed 32 bit integer |
| 32 | */ |
| 33 | SkBool is32() const { return fHi == ((int32_t)fLo >> 31); } |
| 34 | |
| 35 | /** Returns non-zero if the Sk64 cannot be represented as a signed 32 bit integer |
| 36 | */ |
| 37 | SkBool is64() const { return fHi != ((int32_t)fLo >> 31); } |
| 38 | |
| 39 | /** Returns non-zero if the Sk64 can be represented as a signed 48 bit integer. Used to know |
| 40 | if we can shift the value down by 16 to treat it as a SkFixed. |
| 41 | */ |
| 42 | SkBool isFixed() const; |
| 43 | |
| 44 | /** Return the signed 32 bit integer equivalent. Asserts that is32() returns non-zero. |
| 45 | */ |
| 46 | int32_t get32() const { SkASSERT(this->is32()); return (int32_t)fLo; } |
| 47 | |
| 48 | /** Return the number >> 16. Asserts that this does not loose any significant high bits. |
| 49 | */ |
| 50 | SkFixed getFixed() const { |
| 51 | SkASSERT(this->isFixed()); |
| 52 | |
| 53 | uint32_t sum = fLo + (1 << 15); |
| 54 | int32_t hi = fHi; |
| 55 | if (sum < fLo) { |
| 56 | hi += 1; |
| 57 | } |
| 58 | return (hi << 16) | (sum >> 16); |
| 59 | } |
| 60 | |
| 61 | /** Return the number >> 30. Asserts that this does not loose any |
| 62 | significant high bits. |
| 63 | */ |
| 64 | SkFract getFract() const; |
| 65 | |
| 66 | /** Returns the square-root of the number as a signed 32 bit value. */ |
| 67 | int32_t getSqrt() const; |
| 68 | |
| 69 | /** Returns the number of leading zeros of the absolute value of this. |
| 70 | Will return in the range [0..64] |
| 71 | */ |
| 72 | int getClzAbs() const; |
| 73 | |
| 74 | /** Returns non-zero if the number is zero */ |
| 75 | SkBool isZero() const { return (fHi | fLo) == 0; } |
| 76 | |
| 77 | /** Returns non-zero if the number is non-zero */ |
| 78 | SkBool nonZero() const { return fHi | fLo; } |
| 79 | |
| 80 | /** Returns non-zero if the number is negative (number < 0) */ |
| 81 | SkBool isNeg() const { return (uint32_t)fHi >> 31; } |
| 82 | |
| 83 | /** Returns non-zero if the number is positive (number > 0) */ |
| 84 | SkBool isPos() const { return ~(fHi >> 31) & (fHi | fLo); } |
| 85 | |
| 86 | /** Returns -1,0,+1 based on the sign of the number */ |
| 87 | int sign() const { return (fHi >> 31) | Sk32ToBool(fHi | fLo); } |
| 88 | |
| 89 | /** Negate the number */ |
| 90 | void negate(); |
| 91 | |
| 92 | /** If the number < 0, negate the number |
| 93 | */ |
| 94 | void abs(); |
| 95 | |
| 96 | /** Returns the number of bits needed to shift the Sk64 to the right |
| 97 | in order to make it fit in a signed 32 bit integer. |
| 98 | */ |
| 99 | int shiftToMake32() const; |
| 100 | |
| 101 | /** Set the number to zero */ |
| 102 | void setZero() { fHi = fLo = 0; } |
| 103 | |
| 104 | /** Set the high and low 32 bit values of the number */ |
| 105 | void set(int32_t hi, uint32_t lo) { fHi = hi; fLo = lo; } |
| 106 | |
| 107 | /** Set the number to the specified 32 bit integer */ |
| 108 | void set(int32_t a) { fHi = a >> 31; fLo = a; } |
| 109 | |
| 110 | /** Set the number to the product of the two 32 bit integers */ |
| 111 | void setMul(int32_t a, int32_t b); |
| 112 | |
| 113 | /** extract 32bits after shifting right by bitCount. |
| 114 | Note: itCount must be [0..63]. |
| 115 | Asserts that no significant high bits were lost. |
| 116 | */ |
| 117 | int32_t getShiftRight(unsigned bitCount) const; |
| 118 | |
| 119 | /** Shift the number left by the specified number of bits. |
| 120 | @param bits How far to shift left, must be [0..63] |
| 121 | */ |
| 122 | void shiftLeft(unsigned bits); |
| 123 | |
| 124 | /** Shift the number right by the specified number of bits. |
| 125 | @param bits How far to shift right, must be [0..63]. This |
| 126 | performs an arithmetic right-shift (sign extending). |
| 127 | */ |
| 128 | void shiftRight(unsigned bits); |
| 129 | |
| 130 | /** Shift the number right by the specified number of bits, but |
| 131 | round the result. |
| 132 | @param bits How far to shift right, must be [0..63]. This |
| 133 | performs an arithmetic right-shift (sign extending). |
| 134 | */ |
| 135 | void roundRight(unsigned bits); |
| 136 | |
| 137 | /** Add the specified 32 bit integer to the number */ |
| 138 | void add(int32_t lo) { |
| 139 | int32_t hi = lo >> 31; // 0 or -1 |
| 140 | uint32_t sum = fLo + (uint32_t)lo; |
| 141 | |
| 142 | fHi = fHi + hi + (sum < fLo); |
| 143 | fLo = sum; |
| 144 | } |
| 145 | |
| 146 | /** Add the specified Sk64 to the number */ |
| 147 | void add(int32_t hi, uint32_t lo) { |
| 148 | uint32_t sum = fLo + lo; |
| 149 | |
| 150 | fHi = fHi + hi + (sum < fLo); |
| 151 | fLo = sum; |
| 152 | } |
| 153 | |
| 154 | /** Add the specified Sk64 to the number */ |
| 155 | void add(const Sk64& other) { this->add(other.fHi, other.fLo); } |
| 156 | |
| 157 | /** Subtract the specified Sk64 from the number. (*this) = (*this) - num |
| 158 | */ |
| 159 | void sub(const Sk64& num); |
| 160 | |
| 161 | /** Subtract the number from the specified Sk64. (*this) = num - (*this) |
| 162 | */ |
| 163 | void rsub(const Sk64& num); |
| 164 | |
| 165 | /** Multiply the number by the specified 32 bit integer |
| 166 | */ |
| 167 | void mul(int32_t); |
| 168 | |
| 169 | enum DivOptions { |
| 170 | kTrunc_DivOption, //!< truncate the result when calling div() |
| 171 | kRound_DivOption //!< round the result when calling div() |
| 172 | }; |
| 173 | |
| 174 | /** Divide the number by the specified 32 bit integer, using the specified |
| 175 | divide option (either truncate or round). |
| 176 | */ |
| 177 | void div(int32_t, DivOptions); |
| 178 | |
| 179 | /** return (this + other >> 16) as a 32bit result */ |
| 180 | SkFixed addGetFixed(const Sk64& other) const { |
| 181 | return this->addGetFixed(other.fHi, other.fLo); |
| 182 | } |
| 183 | |
| 184 | /** return (this + Sk64(hi, lo) >> 16) as a 32bit result */ |
| 185 | SkFixed addGetFixed(int32_t hi, uint32_t lo) const { |
| 186 | #ifdef SK_DEBUG |
| 187 | Sk64 tmp(*this); |
| 188 | tmp.add(hi, lo); |
| 189 | #endif |
| 190 | |
| 191 | uint32_t sum = fLo + lo; |
| 192 | hi += fHi + (sum < fLo); |
| 193 | lo = sum; |
| 194 | |
| 195 | sum = lo + (1 << 15); |
| 196 | if (sum < lo) |
| 197 | hi += 1; |
| 198 | |
| 199 | hi = (hi << 16) | (sum >> 16); |
| 200 | SkASSERT(hi == tmp.getFixed()); |
| 201 | return hi; |
| 202 | } |
| 203 | |
| 204 | /** Return the result of dividing the number by denom, treating the answer |
| 205 | as a SkFixed. (*this) << 16 / denom. It is an error for denom to be 0. |
| 206 | */ |
| 207 | SkFixed getFixedDiv(const Sk64& denom) const; |
| 208 | |
| 209 | friend bool operator==(const Sk64& a, const Sk64& b) { |
| 210 | return a.fHi == b.fHi && a.fLo == b.fLo; |
| 211 | } |
| 212 | |
| 213 | friend bool operator!=(const Sk64& a, const Sk64& b) { |
| 214 | return a.fHi != b.fHi || a.fLo != b.fLo; |
| 215 | } |
| 216 | |
| 217 | friend bool operator<(const Sk64& a, const Sk64& b) { |
| 218 | return a.fHi < b.fHi || (a.fHi == b.fHi && a.fLo < b.fLo); |
| 219 | } |
| 220 | |
| 221 | friend bool operator<=(const Sk64& a, const Sk64& b) { |
| 222 | return a.fHi < b.fHi || (a.fHi == b.fHi && a.fLo <= b.fLo); |
| 223 | } |
| 224 | |
| 225 | friend bool operator>(const Sk64& a, const Sk64& b) { |
| 226 | return a.fHi > b.fHi || (a.fHi == b.fHi && a.fLo > b.fLo); |
| 227 | } |
| 228 | |
| 229 | friend bool operator>=(const Sk64& a, const Sk64& b) { |
| 230 | return a.fHi > b.fHi || (a.fHi == b.fHi && a.fLo >= b.fLo); |
| 231 | } |
| 232 | |
| 233 | #ifdef SkLONGLONG |
| 234 | SkLONGLONG getLongLong() const; |
| 235 | #endif |
| 236 | |
| 237 | #ifdef SK_DEBUG |
| 238 | /** @cond UNIT_TEST */ |
| 239 | static void UnitTest(); |
| 240 | /** @endcond */ |
| 241 | #endif |
| 242 | }; |
| 243 | |
| 244 | #endif |
| 245 | |