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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 /** | |
6 * An immutable 32-bit signed integer, in the range [-2^31, 2^31 - 1]. | |
7 * Arithmetic operations may overflow in order to maintain this range. | |
8 */ | |
9 class int32 implements intx { | |
10 | |
11 /** | |
12 * The maximum positive value attainable by an [int32], namely | |
13 * 2147483647. | |
14 */ | |
15 static final int32 MAX_VALUE = const int32._internal(0x7FFFFFFF); | |
16 | |
17 /** | |
18 * The minimum positive value attainable by an [int32], namely | |
19 * -2147483648. | |
20 */ | |
21 static int32 MIN_VALUE = const int32._internal(0x80000000); | |
22 | |
23 /** | |
24 * An [int32] constant equal to 0. | |
25 */ | |
26 static int32 ZERO = const int32._internal(0); | |
27 | |
28 /** | |
29 * An [int32] constant equal to 1. | |
30 */ | |
31 static int32 ONE = const int32._internal(1); | |
32 | |
33 /** | |
34 * An [int32] constant equal to 2. | |
35 */ | |
36 static int32 TWO = const int32._internal(2); | |
37 | |
38 // Hex digit char codes | |
39 static final int _CC_0 = 48; // '0'.charCodeAt(0) | |
40 static final int _CC_9 = 57; // '9'.charCodeAt(0) | |
41 static final int _CC_a = 97; // 'a'.charCodeAt(0) | |
42 static final int _CC_z = 122; // 'z'.charCodeAt(0) | |
43 static final int _CC_A = 65; // 'A'.charCodeAt(0) | |
44 static final int _CC_Z = 90; // 'Z'.charCodeAt(0) | |
45 | |
46 static int _decodeHex(int c) { | |
47 if (c >= _CC_0 && c <= _CC_9) { | |
48 return c - _CC_0; | |
49 } else if (c >= _CC_a && c <= _CC_z) { | |
50 return c - _CC_a + 10; | |
51 } else if (c >= _CC_A && c <= _CC_Z) { | |
52 return c - _CC_A + 10; | |
53 } else { | |
54 return -1; // bad char code | |
55 } | |
56 } | |
57 | |
58 /** | |
59 * Parses a [String] in a given [radix] between 2 and 16 and returns an | |
60 * [int32]. | |
61 */ | |
62 // TODO(rice) - Make this faster by converting several digits at once. | |
63 static int32 parseRadix(String s, int radix) { | |
64 if ((radix <= 1) || (radix > 16)) { | |
65 throw "Bad radix: $radix"; | |
66 } | |
67 int32 x = ZERO; | |
68 for (int i = 0; i < s.length; i++) { | |
69 int c = s.charCodeAt(i); | |
70 int digit = _decodeHex(c); | |
71 if (digit < 0 || digit >= radix) { | |
72 throw new Exception("Non-radix char code: $c"); | |
73 } | |
74 x = (x * radix) + digit; | |
75 } | |
76 return x; | |
77 } | |
78 | |
79 /** | |
80 * Parses a decimal [String] and returns an [int32]. | |
81 */ | |
82 static int32 parseInt(String s) => new int32.fromInt(Math.parseInt(s)); | |
83 | |
84 /** | |
85 * Parses a hexadecimal [String] and returns an [int32]. | |
86 */ | |
87 static int32 parseHex(String s) => parseRadix(s, 16); | |
88 | |
89 // Assumes i is <= 32-bit. | |
90 static int _bitCount(int i) { | |
91 // See "Hacker's Delight", section 5-1, "Counting 1-Bits". | |
92 | |
93 // The basic strategy is to use "divide and conquer" to | |
94 // add pairs (then quads, etc.) of bits together to obtain | |
95 // sub-counts. | |
96 // | |
97 // A straightforward approach would look like: | |
98 // | |
99 // i = (i & 0x55555555) + ((i >> 1) & 0x55555555); | |
100 // i = (i & 0x33333333) + ((i >> 2) & 0x33333333); | |
101 // i = (i & 0x0F0F0F0F) + ((i >> 4) & 0x0F0F0F0F); | |
102 // i = (i & 0x00FF00FF) + ((i >> 8) & 0x00FF00FF); | |
103 // i = (i & 0x0000FFFF) + ((i >> 16) & 0x0000FFFF); | |
104 // | |
105 // The code below removes unnecessary &'s and uses a | |
106 // trick to remove one instruction in the first line. | |
107 | |
108 i -= ((i >> 1) & 0x55555555); | |
109 i = (i & 0x33333333) + ((i >> 2) & 0x33333333); | |
110 i = ((i + (i >> 4)) & 0x0F0F0F0F); | |
111 i += (i >> 8); | |
112 i += (i >> 16); | |
113 return (i & 0x0000003F); | |
114 } | |
115 | |
116 // Assumes i is <= 32-bit | |
117 static int _numberOfLeadingZeros(int i) { | |
118 i |= i >> 1; | |
119 i |= i >> 2; | |
120 i |= i >> 4; | |
121 i |= i >> 8; | |
122 i |= i >> 16; | |
123 return _bitCount(~i); | |
124 } | |
125 | |
126 static int _numberOfTrailingZeros(int i) => _bitCount((i & -i) - 1); | |
127 | |
128 // The internal value, kept in the range [MIN_VALUE, MAX_VALUE]. | |
129 final int _i; | |
130 | |
131 const int32._internal(int i) : _i = i; | |
132 | |
133 /** | |
134 * Constructs an [int32] from an [int]. Only the low 32 bits of the input | |
135 * are used. | |
136 */ | |
137 int32.fromInt(int i) : _i = (i & 0x7fffffff) - (i & 0x80000000); | |
138 | |
139 // Convert an [int] or [intx] to an [int32]. Note that an [int64] | |
140 // will be truncated. | |
141 int _convert(other) { | |
142 if (other == null) { | |
143 throw new NullPointerException(); | |
144 } else if (other is intx) { | |
145 return other.toInt32()._i; | |
146 } else if (other is int) { | |
147 return other; | |
148 } else { | |
149 throw new Exception("Can't retrieve 32-bit int from $other"); | |
150 } | |
151 } | |
152 | |
153 // The +, -, * , &, |, and ^ operaters deal with types as follows: | |
154 // | |
155 // int32 + int => int32 | |
156 // int32 + int32 => int32 | |
157 // int32 + int64 => int64 | |
158 // | |
159 // The %, ~/ and remainder operators return an int32 even with an int64 | |
160 // argument, since the result cannot be greater than the value on the | |
161 // left-hand side: | |
162 // | |
163 // int32 % int => int32 | |
164 // int32 % int32 => int32 | |
165 // int32 % int64 => int32 | |
166 | |
167 intx operator +(other) { | |
168 if (other is int64) { | |
169 return this.toInt64() + other; | |
170 } | |
171 return new int32.fromInt(_i + _convert(other)); | |
172 } | |
173 | |
174 intx operator -(other) { | |
175 if (other is int64) { | |
176 return this.toInt64() - other; | |
177 } | |
178 return new int32.fromInt(_i - _convert(other)); | |
179 } | |
180 | |
181 int32 operator negate() => new int32.fromInt(-_i); | |
182 | |
183 intx operator *(other) { | |
184 if (other is int64) { | |
185 return this.toInt64() * other; | |
186 } | |
187 // TODO(rice) - optimize | |
188 return (this.toInt64() * other).toInt32(); | |
189 } | |
190 | |
191 int32 operator %(other) { | |
192 if (other is int64) { | |
193 // Result will be int32 | |
194 return (this.toInt64() % other).toInt32(); | |
195 } | |
196 return new int32.fromInt(_i % _convert(other)); | |
197 } | |
198 | |
199 int32 operator ~/(other) { | |
200 if (other is int64) { | |
201 // Result will be int32 | |
202 return (this.toInt64() ~/ other).toInt32(); | |
203 } | |
204 return new int32.fromInt(_i ~/ _convert(other)); | |
205 } | |
206 | |
207 int32 remainder(other) { | |
208 if (other is int64) { | |
209 // Result will be int32 | |
210 int64 t = this.toInt64(); | |
211 return (t - (t ~/ other) * other).toInt32(); | |
212 } | |
213 return this - (this ~/ other) * other; | |
214 } | |
215 | |
216 int32 operator &(other) { | |
217 if (other is int64) { | |
218 return (this.toInt64() & other).toInt32(); | |
219 } | |
220 return new int32.fromInt(_i & _convert(other)); | |
221 } | |
222 | |
223 int32 operator |(other) { | |
224 if (other is int64) { | |
225 return (this.toInt64() | other).toInt32(); | |
226 } | |
227 return new int32.fromInt(_i | _convert(other)); | |
228 } | |
229 | |
230 int32 operator ^(other) { | |
231 if (other is int64) { | |
232 return (this.toInt64() ^ other).toInt32(); | |
233 } | |
234 return new int32.fromInt(_i ^ _convert(other)); | |
235 } | |
236 | |
237 int32 operator ~() => new int32.fromInt(~_i); | |
238 | |
239 int32 operator <<(int n) { | |
240 if (n < 0) { | |
241 throw new IllegalArgumentException("$n"); | |
242 } | |
243 n &= 31; | |
244 return new int32.fromInt(_i << n); | |
245 } | |
246 | |
247 int32 operator >>(int n) { | |
248 if (n < 0) { | |
249 throw new IllegalArgumentException("$n"); | |
250 } | |
251 n &= 31; | |
252 int value; | |
253 if (_i >= 0) { | |
254 value = _i >> n; | |
255 } else { | |
256 value = (_i >> n) | (0xffffffff << (32 - n)); | |
257 } | |
258 return new int32.fromInt(value); | |
259 } | |
260 | |
261 int32 shiftRightUnsigned(int n) { | |
262 if (n < 0) { | |
263 throw new IllegalArgumentException("$n"); | |
264 } | |
265 n &= 31; | |
266 int value; | |
267 if (_i >= 0) { | |
268 value = _i >> n; | |
269 } else { | |
270 value = (_i >> n) & ((1 << (32 - n)) - 1); | |
271 } | |
272 return new int32.fromInt(value); | |
273 } | |
274 | |
275 /** | |
276 * Returns [true] if this [int32] has the same numeric value as the | |
277 * given object. The argument may be an [int] or an [intx]. | |
278 */ | |
279 bool operator ==(other) { | |
280 if (other == null) { | |
281 return false; | |
282 } | |
283 if (other is int64) { | |
284 return this.toInt64() == other; | |
285 } | |
286 return _i == _convert(other); | |
287 } | |
288 | |
289 int compareTo(Comparable other) { | |
290 if (other is int64) { | |
291 return this.toInt64().compareTo(other); | |
292 } | |
293 return _i.compareTo(_convert(other)); | |
294 } | |
295 | |
296 bool operator <(other) { | |
297 if (other is int64) { | |
298 return this.toInt64() < other; | |
299 } | |
300 return _i < _convert(other); | |
301 } | |
302 | |
303 bool operator <=(other) { | |
304 if (other is int64) { | |
305 return this.toInt64() < other; | |
306 } | |
307 return _i <= _convert(other); | |
308 } | |
309 | |
310 bool operator >(other) { | |
311 if (other is int64) { | |
312 return this.toInt64() < other; | |
313 } | |
314 return _i > _convert(other); | |
315 } | |
316 | |
317 bool operator >=(other) { | |
318 if (other is int64) { | |
319 return this.toInt64() < other; | |
320 } | |
321 return _i >= _convert(other); | |
322 } | |
323 | |
324 bool isEven() => (_i & 0x1) == 0; | |
325 bool isMaxValue() => _i == 2147483647; | |
326 bool isMinValue() => _i == -2147483648; | |
327 bool isNegative() => _i < 0; | |
328 bool isOdd() => (_i & 0x1) == 1; | |
329 bool isZero() => _i == 0; | |
330 | |
331 int hashCode() => _i; | |
332 | |
333 int32 abs() => _i < 0 ? new int32.fromInt(-_i) : this; | |
334 | |
335 int numberOfLeadingZeros() => _numberOfLeadingZeros(_i); | |
336 int numberOfTrailingZeros() => _numberOfTrailingZeros(_i); | |
337 | |
338 List<int> toBytes() { | |
339 List<int> result = new List<int>(4); | |
340 result[0] = _i & 0xff; | |
341 result[1] = (_i >> 8) & 0xff; | |
342 result[2] = (_i >> 16) & 0xff; | |
343 result[3] = (_i >> 24) & 0xff; | |
344 return result; | |
345 } | |
346 | |
347 int toInt() => _i; | |
348 int32 toInt32() => this; | |
349 int64 toInt64() => new int64.fromInt(_i); | |
350 | |
351 String toString() => _i.toString(); | |
352 String toHexString() => _i.toRadixString(16); | |
353 String toRadixString(int radix) => _i.toRadixString(radix); | |
354 } | |
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