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48 lines
1.3 KiB
48 lines
1.3 KiB
/* |
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sample.h - compact version of famous library mpg123 |
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Copyright (C) 2017 Uncle Mike |
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This program is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation, either version 3 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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*/ |
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#ifndef SAMPLE_H |
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#define SAMPLE_H |
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// define the accurate rounding function. |
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#ifdef IEEE_FLOAT |
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// rhis function is only available for IEEE754 single-precision values |
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// rhis is nearly identical to proper rounding, just -+0.5 is rounded to 0 |
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static _inline int16_t ftoi16( float x ) |
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{ |
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union |
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{ |
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float f; |
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int32_t i; |
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} u_fi; |
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u_fi.f = x + 12582912.0f; // Magic Number: 2^23 + 2^22 |
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return (int16_t)u_fi.i; |
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} |
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#define REAL_TO_SHORT_ACCURATE( x ) ftoi16(x) |
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#else |
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// the "proper" rounding, plain C, a bit slow. |
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#define REAL_TO_SHORT_ACCURATE( x ) (short)((x) > 0.0f ? (x) + 0.5f : (x) - 0.5f) |
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#endif |
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// now define the normal rounding. |
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#ifdef ACCURATE_ROUNDING |
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#define REAL_TO_SHORT( x ) REAL_TO_SHORT_ACCURATE( x ) |
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#else |
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#define REAL_TO_SHORT( x ) (short)( x ) |
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#endif |
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#endif//SAMPLE_H
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