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docs: FastMath

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This commit is contained in:
Hannes Janetzek 2014-02-07 15:59:14 +01:00
parent ebaffdb123
commit e71f866b14
1 changed files with 18 additions and 19 deletions
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37
vtm/src/org/oscim/utils/FastMath.java
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@ -18,43 +18,42 @@ package org.oscim.utils;
public class FastMath {
/**
* from http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
* Integer version of log2(x)
*
* @param v
* ...
* @return ...
* from http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
*/
public static int log2(int v) {
public static int log2(int x) {
int r = 0; // result of log2(v) will go here
if ((v & 0xFFFF0000) != 0) {
v >>= 16;
if ((x & 0xFFFF0000) != 0) {
x >>= 16;
r |= 16;
}
if ((v & 0xFF00) != 0) {
v >>= 8;
if ((x & 0xFF00) != 0) {
x >>= 8;
r |= 8;
}
if ((v & 0xF0) != 0) {
v >>= 4;
if ((x & 0xF0) != 0) {
x >>= 4;
r |= 4;
}
if ((v & 0xC) != 0) {
v >>= 2;
if ((x & 0xC) != 0) {
x >>= 2;
r |= 2;
}
if ((v & 0x2) != 0) {
if ((x & 0x2) != 0) {
r |= 1;
}
return r;
}
public static float pow(int pow) {
if (pow == 0)
/** Integer version of 2^x */
public static float pow(int x) {
if (x == 0)
return 1;
return (pow > 0 ? (1 << pow) : (1.0f / (1 << -pow)));
return (x > 0 ? (1 << x) : (1.0f / (1 << -x)));
}
public static int clamp(int value, int min, int max) {
@ -87,12 +86,12 @@ public class FastMath {
return a2 < a1 ? a1 : a2;
}
// test if any absolute value is greater than 'cmp'
/** test if any absolute value is greater than 'cmp' */
public static boolean absMaxCmp(float value1, float value2, float cmp) {
return value1 < -cmp || value1 > cmp || value2 < -cmp || value2 > cmp;
}
// test if any absolute value is greater than 'cmp'
/** test if any absolute value is greater than 'cmp' */
public static boolean absMaxCmp(int value1, int value2, int cmp) {
return value1 < -cmp || value1 > cmp || value2 < -cmp || value2 > cmp;
}