HDK: UT/UT_ISqrt.h Source File

00001 /*
00002  * PROPRIETARY INFORMATION.  This software is proprietary to
00003  * Side Effects Software Inc., and is not to be reproduced,
00004  * transmitted, or disclosed in any way without written permission.
00005  *
00006  * Produced by:
00007  *      Mark Elendt
00008  *      Side Effects
00009  *      477 Richmond Street West
00010  *      Toronto, Ontario
00011  *      Canada   M5V 3E7
00012  *      416-504-9876
00013  *
00014  * NAME:        UT library (C++)
00015  *
00016  * COMMENTS:    Fast lookup to get integer square roots.  The square roots
00017  *              will round, thus UTisqrt(3) = 2, UTisqrt(2) = 1
00018  *              The table is good for positive integers up to 1024
00019  *
00020  */
00021 
00022 #ifndef __UT_ISqrt_h__
00023 #define __UT_ISqrt_h__
00024 
00025 #include "UT_API.h"
00026 #include <SYS/SYS_Types.h>
00027 
00028 #define MAX_ISQRT       1024
00029 
00030 UT_API extern int       UTisqrtTable[];
00031 UT_API extern float     UTinvSqrtTable[];
00032 
00033 UT_API unsigned int     UTbigISqrt(unsigned int val);
00034 
00035 inline int      UTisqrtFast(unsigned val)         { return UTisqrtTable[val]; }
00036 inline float    UTinverseSqrtFast(unsigned val) { return UTinvSqrtTable[val]; }
00037 
00038 inline int
00039 UTisqrt(unsigned val)
00040 {
00041     return val <= MAX_ISQRT ? UTisqrtTable[val] : UTbigISqrt(val);
00042 }
00043 
00044 inline float
00045 UTinverseSqrt(unsigned val)
00046 {
00047     return val <= MAX_ISQRT ? UTinvSqrtTable[val]
00048                             : 1.0F/(float)UTbigISqrt(val);
00049 }
00050 
00051 #endif