60 lines
2.0 KiB
C
60 lines
2.0 KiB
C
/**
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* Copyright 2022 Colin Lam, Ploopy Corporation
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*
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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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*
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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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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* SPECIAL THANKS TO:
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* Ben Brewer, a.k.a. flatmush
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* for his exceptional work on libfixmath, on which this is based.
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*/
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#ifndef FIX16_H
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#define FIX16_H
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#include <stdbool.h>
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#include <inttypes.h>
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// During development, it can be useful to run with real double values for reference.
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//#define USE_DOUBLE
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#ifdef USE_DOUBLE
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typedef double fix16_t;
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static const fix16_t fix16_zero = 0;
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static const fix16_t fix16_one = 1;
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#else
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/// @brief Fixed point math type, in format Q3.28. One sign bit, 3 bits for left-of-decimal
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///and 28 for right-of-decimal. This arrangment works because we normalize the incoming USB
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///audio data to ]-1,1[ before operating on it, to push as much of the precision in the signal
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///to the right of the decimal as possible.
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typedef int32_t fix3_28_t;
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/// @brief Represents the number 1 in Q3.28. There are 3 bits and a sign bit to the left of the
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///decimal, so 1.0000 would be represented as 0b 0001 followed by 28 zeros.
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static const fix3_28_t fix16_one = 0x10000000;
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/// @brief Represents zero in fixed point world.
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static const fix3_28_t fix16_zero = 0x00000000;
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#endif
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fix3_28_t norm_fix3_28_from_s16sample(int16_t);
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int16_t norm_fix3_28_to_s16sample(fix3_28_t);
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fix3_28_t fix3_28_from_dbl(double);
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fix3_28_t fix16_mul(fix3_28_t, fix3_28_t);
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#endif |