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