mirror of
https://github.com/dart-lang/sdk
synced 2024-09-18 21:41:19 +00:00
ce4b15c0e9
- bit length
- truncate to signed fixed width integer
- truncate to unsigned fixed width integer
This change is motivated by a program that spends 20-30% of its time here:
// TODO(5828): Replace this with a bit-length method on int when available.
int n_bitLength = this.n.toRadixString(2).length;
See Also
https://code.google.com/p/dart/issues/detail?id=5828#c3
https://code.google.com/p/dart/issues/detail?id=6486#c2
https://code.google.com/p/dart/issues/detail?id=5798#c5
https://code.google.com/p/dart/issues/detail?id=12008
R=lrn@google.com, srdjan@google.com
Review URL: https://codereview.chromium.org//23645003
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27269 260f80e4-7a28-3924-810f-c04153c831b5
62 lines
1.9 KiB
Dart
62 lines
1.9 KiB
Dart
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// Testing Bigints.
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library bit_twiddling_test;
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import "package:expect/expect.dart";
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// See bit_twiddling_test.dart first. This file contains only the tests that
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// need Bigint or would fail in dart2js compatibility mode.
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testBitLength() {
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check(int i, width) {
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Expect.equals(width, i.bitLength, '$i.bitLength == $width');
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// (~i) written as (-i-1) to avoid issues with limited range of dart2js ops.
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Expect.equals(width, (-i-1).bitLength, '(~$i).bitLength == $width');
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}
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check(0xffffffffffffff, 56);
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check(0xffffffffffffffff, 64);
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check(0xffffffffffffffffff, 72);
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check(0x1000000000000000000, 73);
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check(0x1000000000000000001, 73);
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check(0xfffffffffffffffffffffffffffffffffffffe, 152);
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check(0xffffffffffffffffffffffffffffffffffffff, 152);
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check(0x100000000000000000000000000000000000000, 153);
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check(0x100000000000000000000000000000000000001, 153);
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}
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testToUnsigned() {
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checkU(src, width, expected) {
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Expect.equals(expected, src.toUnsigned(width));
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}
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checkU(0x100000100000000000001, 2, 1);
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checkU(0x100000200000000000001, 60, 0x200000000000001);
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checkU(0x100000200000000000001, 59, 0x200000000000001);
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checkU(0x100000200000000000001, 58, 0x200000000000001);
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checkU(0x100000200000000000001, 57, 1);
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}
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testToSigned() {
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checkS(src, width, expected) {
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Expect.equals(expected, src.toSigned(width),
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'$src.toSigned($width) == $expected');
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}
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checkS(0x100000100000000000001, 2, 1);
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checkS(0x100000200000000000001, 60, 0x200000000000001);
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checkS(0x100000200000000000001, 59, 0x200000000000001);
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checkS(0x100000200000000000001, 58, -0x200000000000000 + 1);
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checkS(0x100000200000000000001, 57, 1);
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}
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main() {
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testBitLength();
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testToUnsigned();
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testToSigned();
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}
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