+ Press n or j to go to the next uncovered block, b, p or k for the previous block. +
+ +| File | ++ | Statements | ++ | Branches | ++ | Functions | ++ | Lines | ++ |
|---|---|---|---|---|---|---|---|---|---|
| index.js | +
+
+ |
+ 100% | +46/46 | +100% | +1/1 | +100% | +0/0 | +100% | +46/46 | +
| main.js | +
+
+ |
+ 100% | +129/129 | +100% | +7/7 | +100% | +1/1 | +100% | +129/129 | +
| native.js | +
+
+ |
+ 100% | +54/54 | +100% | +2/2 | +100% | +1/1 | +100% | +54/54 | +
+ Press n or j to go to the next uncovered block, b, p or k for the previous block. +
+ +| 1 +2 +3 +4 +5 +6 +7 +8 +9 +10 +11 +12 +13 +14 +15 +16 +17 +18 +19 +20 +21 +22 +23 +24 +25 +26 +27 +28 +29 +30 +31 +32 +33 +34 +35 +36 +37 +38 +39 +40 +41 +42 +43 +44 +45 +46 +47 | 1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x + | /** +* @license Apache-2.0 +* +* Copyright (c) 2018 The Stdlib Authors. +* +* Licensed under the Apache License, Version 2.0 (the "License"); +* you may not use this file except in compliance with the License. +* You may obtain a copy of the License at +* +* http://www.apache.org/licenses/LICENSE-2.0 +* +* Unless required by applicable law or agreed to in writing, software +* distributed under the License is distributed on an "AS IS" BASIS, +* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +* See the License for the specific language governing permissions and +* limitations under the License. +*/ + +'use strict'; + +/** +* Integer binary logarithm (base two). +* +* @module @stdlib/math/base/special/fast/uint32-log2 +* +* @example +* var log2Uint32 = require( '@stdlib/math/base/special/fast/uint32-log2' ); +* +* var v = log2Uint32( 4 >>> 0 ); +* // returns 2 +* +* v = log2Uint32( 8 >>> 0 ); +* // returns 3 +* +* v = log2Uint32( 9 >>> 0 ); +* // returns 3 +*/ + +// MODULES // + +var log2Uint32 = require( './main.js' ); + + +// EXPORTS // + +module.exports = log2Uint32; + |
+ Press n or j to go to the next uncovered block, b, p or k for the previous block. +
+ +| 1 +2 +3 +4 +5 +6 +7 +8 +9 +10 +11 +12 +13 +14 +15 +16 +17 +18 +19 +20 +21 +22 +23 +24 +25 +26 +27 +28 +29 +30 +31 +32 +33 +34 +35 +36 +37 +38 +39 +40 +41 +42 +43 +44 +45 +46 +47 +48 +49 +50 +51 +52 +53 +54 +55 +56 +57 +58 +59 +60 +61 +62 +63 +64 +65 +66 +67 +68 +69 +70 +71 +72 +73 +74 +75 +76 +77 +78 +79 +80 +81 +82 +83 +84 +85 +86 +87 +88 +89 +90 +91 +92 +93 +94 +95 +96 +97 +98 +99 +100 +101 +102 +103 +104 +105 +106 +107 +108 +109 +110 +111 +112 +113 +114 +115 +116 +117 +118 +119 +120 +121 +122 +123 +124 +125 +126 +127 +128 +129 +130 | 1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +5032x +5032x +5032x +5032x +5032x +5032x +5014x +5014x +5014x +5032x +5032x +4974x +4974x +4974x +5032x +5032x +4426x +4426x +4426x +5032x +5032x +3000x +3000x +3000x +5032x +5032x +1707x +1707x +1707x +5032x +5032x +1x +1x +1x +1x +1x + | /**
+* @license Apache-2.0
+*
+* Copyright (c) 2018 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// VARIABLES //
+
+// 4294901760 => 0xFFFF0000 => 11111111111111110000000000000000
+var B4 = 0xFFFF0000 >>> 0; // asm type annotation
+
+// 65280 => 0xFF00 => 00000000000000001111111100000000
+var B3 = 0xFF00 >>> 0; // asm type annotation
+
+// 240 => 0xF0 => 00000000000000000000000011110000
+var B2 = 0xF0 >>> 0; // asm type annotation
+
+// 12 => 0xC => 00000000000000000000000000001100
+var B1 = 0xC >>> 0; // asm type annotation
+
+// 2 => 0x2 => 00000000000000000000000000000010
+var B0 = 0x2 >>> 0; // asm type annotation
+
+// 16 => 00000000000000000000000000010000
+var S4 = 16 >>> 0; // asm type annotation
+
+// 8 => 00000000000000000000000000001000
+var S3 = 8 >>> 0; // asm type annotation
+
+// 4 => 00000000000000000000000000000100
+var S2 = 4 >>> 0; // asm type annotation
+
+// 2 => 00000000000000000000000000000010
+var S1 = 2 >>> 0; // asm type annotation
+
+// 1 => 00000000000000000000000000000001
+var S0 = 1 >>> 0; // asm type annotation
+
+
+// MAIN //
+
+/**
+* Computes an integer binary logarithm (base two).
+*
+* ## Method
+*
+* 1. Note that the largest unsigned 32-bit integer is `4294967295`, which is `2^{32}-1`. Hence, the integer binary logarithm cannot exceed `31` (i.e., `16 + 8 + 4 + 2 + 1`), which corresponds to the bit sequence
+*
+* ```binarystring
+* 00000000000000000000000000011111
+* ```
+*
+* 2. Initialize a return variable with the value zero.
+*
+* 3. If at least one of the first sixteen most significant bits of the input 32-bit integer `x` is turned on, we know that the power to which the number `2` must be raised to obtain `x` is at least `16` (i.e., `x > 65536`). Hence, activate the corresponding bit of the return variable. Mutate `x` by shifting sixteen bits to the right, discarding the bits shifted off.
+*
+* 4. Carry out the following steps with `B` in `[ 8, 4, 2, 1 ]`:
+*
+* - If at least one of the next `B` most significant bits of the current `x` is turned on, we know that the power to which the number `2` must be raised to obtain `x` has to be increased by `B`.
+* - Activate the bit of the return variable that corresponds to `B`.
+* - Mutate `x` by shifting `B` bits to the right, discarding the bits shifted off.
+*
+* 5. The final value of the return variable is the integer binary logarithm of `x`.
+*
+* @param {uinteger32} x - input value
+* @returns {uinteger32} integer binary logarithm
+*
+* @example
+* var v = log2( 4 >>> 0 );
+* // returns 2
+*
+* @example
+* var v = log2( 8 >>> 0 );
+* // returns 3
+*
+* @example
+* var v = log2( 9 >>> 0 );
+* // returns 3
+*/
+function log2( x ) {
+ var out = 0 >>> 0; // asm type annotation
+ var y = x >>> 0; // asm type annotation
+
+ // `x >= 65536`:
+ if ( y & B4 ) {
+ y >>>= S4;
+ out |= S4;
+ }
+ // `x >= 256`:
+ if ( y & B3 ) {
+ y >>>= S3;
+ out |= S3;
+ }
+ // `x >= 16`:
+ if ( y & B2 ) {
+ y >>>= S2;
+ out |= S2;
+ }
+ // `x >= 4`:
+ if ( y & B1 ) {
+ y >>>= S1;
+ out |= S1;
+ }
+ // `x >= 2`:
+ if ( y & B0 ) {
+ y >>>= S0;
+ out |= S0;
+ }
+ return out;
+}
+
+
+// EXPORTS //
+
+module.exports = log2;
+ |
+ Press n or j to go to the next uncovered block, b, p or k for the previous block. +
+ +| 1 +2 +3 +4 +5 +6 +7 +8 +9 +10 +11 +12 +13 +14 +15 +16 +17 +18 +19 +20 +21 +22 +23 +24 +25 +26 +27 +28 +29 +30 +31 +32 +33 +34 +35 +36 +37 +38 +39 +40 +41 +42 +43 +44 +45 +46 +47 +48 +49 +50 +51 +52 +53 +54 +55 | 1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +1x +5032x +5032x +5032x +1x +1x +1x +1x +1x + | /**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var addon = require( './../src/addon.node' );
+
+
+// MAIN //
+
+/**
+* Computes an integer binary logarithm (base two).
+*
+* @private
+* @param {uinteger32} x - input value
+* @returns {uinteger32} integer binary logarithm
+*
+* @example
+* var out = log2Uint32( 4 );
+* // returns 2
+*
+* @example
+* var out = log2Uint32( 8 );
+* // returns 3
+*
+* @example
+* var out = log2Uint32( 9 );
+* // returns 3
+*/
+function log2Uint32( x ) {
+ return addon( x );
+}
+
+
+// EXPORTS //
+
+module.exports = log2Uint32;
+ |