/** 
 * @file llquantize.h
 * @brief useful routines for quantizing floats to various length ints
 * and back out again
 *
 * $LicenseInfo:firstyear=2001&license=viewergpl$
 * 
 * Copyright (c) 2001-2008, Linden Research, Inc.
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 */

#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_ROUND(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);

	// round the value.   Sreturn the U16
	return (U16)(llround(val*U16MAX));
}


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_ROUND(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 rounded U8
	return (U8)(llround(val*U8MAX));
}


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