36 lines
938 B
Haxe
36 lines
938 B
Haxe
package kha.audio2.ogg.tools;
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/**
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* ...
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* @author shohei909
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*/
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class MathTools
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{
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public static inline function ilog(n:Int)
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{
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var log2_4 = [0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4];
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// 2 compares if n < 16, 3 compares otherwise (4 if signed or n > 1<<29)
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return if (n < (1 << 14)) {
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if (n < (1 << 4)) {
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0 + log2_4[n];
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} else if (n < (1 << 9)) {
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5 + log2_4[n >> 5];
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} else {
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10 + log2_4[n >> 10];
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}
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} else if (n < (1 << 24)) {
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if (n < (1 << 19)) {
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15 + log2_4[n >> 15];
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} else {
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20 + log2_4[n >> 20];
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}
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} else if (n < (1 << 29)) {
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25 + log2_4[n >> 25];
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} else if (n < (1 << 31)) {
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30 + log2_4[n >> 30];
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} else {
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0; // signed n returns 0
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}
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}
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} |