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/**
* @file llquantize.h
* @brief useful routines for quantizing floats to various length ints
* and back out again
*
* Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#ifndef LL_LLQUANTIZE_H
#define LL_LLQUANTIZE_H
const U16 U16MAX = 65535;
const F32 OOU16MAX = 1.f/(F32)(U16MAX);
const U8 U8MAX = 255;
const F32 OOU8MAX = 1.f/(F32)(U8MAX);
const U8 FIRSTVALIDCHAR = 54;
const U8 MAXSTRINGVAL = U8MAX - FIRSTVALIDCHAR; //we don't allow newline or null
inline U16 F32_to_U16(F32 val, F32 lower, F32 upper)
{
val = llclamp(val, lower, upper);
// make sure that the value is positive and normalized to <0, 1>
val -= lower;
val /= (upper - lower);
// return the U16
return (U16)(llfloor(val*U16MAX));
}
inline F32 U16_to_F32(U16 ival, F32 lower, F32 upper)
{
F32 val = ival*OOU16MAX;
F32 delta = (upper - lower);
val *= delta;
val += lower;
F32 max_error = delta*OOU16MAX;
// make sure that zero's come through as zero
if (fabsf(val) < max_error)
val = 0.f;
return val;
}
inline U8 F32_to_U8(F32 val, F32 lower, F32 upper)
{
val = llclamp(val, lower, upper);
// make sure that the value is positive and normalized to <0, 1>
val -= lower;
val /= (upper - lower);
// return the U8
return (U8)(llfloor(val*U8MAX));
}
inline F32 U8_to_F32(U8 ival, F32 lower, F32 upper)
{
F32 val = ival*OOU8MAX;
F32 delta = (upper - lower);
val *= delta;
val += lower;
F32 max_error = delta*OOU8MAX;
// make sure that zero's come through as zero
if (fabsf(val) < max_error)
val = 0.f;
return val;
}
inline U8 F32_TO_STRING(F32 val, F32 lower, F32 upper)
{
val = llclamp(val, lower, upper); //[lower, upper]
// make sure that the value is positive and normalized to <0, 1>
val -= lower; //[0, upper-lower]
val /= (upper - lower); //[0,1]
val = val * MAXSTRINGVAL; //[0, MAXSTRINGVAL]
val = floor(val + 0.5f); //[0, MAXSTRINGVAL]
U8 stringVal = (U8)(val) + FIRSTVALIDCHAR; //[FIRSTVALIDCHAR, MAXSTRINGVAL + FIRSTVALIDCHAR]
return stringVal;
}
inline F32 STRING_TO_F32(U8 ival, F32 lower, F32 upper)
{
// remove empty space left for NULL, newline, etc.
ival -= FIRSTVALIDCHAR; //[0, MAXSTRINGVAL]
F32 val = (F32)ival * (1.f / (F32)MAXSTRINGVAL); //[0, 1]
F32 delta = (upper - lower);
val *= delta; //[0, upper - lower]
val += lower; //[lower, upper]
return val;
}
#endif
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