118 lines
3.7 KiB
C
118 lines
3.7 KiB
C
/* FluidSynth - A Software Synthesizer
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*
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* Copyright (C) 2003 Peter Hanappe and others.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public License
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* as published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*/
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#ifndef _FLUID_PHASE_H
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#define _FLUID_PHASE_H
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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/*
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* phase
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*/
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#define FLUID_INTERP_BITS 8
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#define FLUID_INTERP_BITS_MASK 0xff000000
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#define FLUID_INTERP_BITS_SHIFT 24
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#define FLUID_INTERP_MAX 256
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#define FLUID_FRACT_MAX ((double)4294967296.0)
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/* fluid_phase_t
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* Purpose:
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* Playing pointer for voice playback
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*
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* When a sample is played back at a different pitch, the playing pointer in the
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* source sample will not advance exactly one sample per output sample.
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* This playing pointer is implemented using fluid_phase_t.
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* It is a 64 bit number. The higher 32 bits contain the 'index' (number of
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* the current sample), the lower 32 bits the fractional part.
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*/
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typedef unsigned long long fluid_phase_t;
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/* Purpose:
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* Set a to b.
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* a: fluid_phase_t
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* b: fluid_phase_t
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*/
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#define fluid_phase_set(a,b) a=b;
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#define fluid_phase_set_int(a, b) ((a) = ((unsigned long long)(b)) << 32)
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/* Purpose:
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* Sets the phase a to a phase increment given in b.
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* For example, assume b is 0.9. After setting a to it, adding a to
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* the playing pointer will advance it by 0.9 samples. */
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#define fluid_phase_set_float(a, b) \
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(a) = (((unsigned long long)(b)) << 32) \
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/* create a fluid_phase_t from an index and a fraction value */
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#define fluid_phase_from_index_fract(index, fract) \
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((((unsigned long long)(index)) << 32) + (fract))
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/* Purpose:
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* Return the index and the fractional part, respectively. */
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#define fluid_phase_index(_x) \
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((unsigned int)((_x) >> 32))
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#define fluid_phase_fract(_x) \
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((uint32)((_x) & 0xFFFFFFFF))
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/* Get the phase index with fractional rounding */
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#define fluid_phase_index_round(_x) \
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((unsigned int)(((_x) + 0x80000000) >> 32))
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/* Purpose:
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* Takes the fractional part of the argument phase and
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* calculates the corresponding position in the interpolation table.
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* The fractional position of the playing pointer is calculated with a quite high
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* resolution (32 bits). It would be unpractical to keep a set of interpolation
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* coefficients for each possible fractional part...
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*/
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#define fluid_phase_fract_to_tablerow(_x) \
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((unsigned int)(fluid_phase_fract(_x) & FLUID_INTERP_BITS_MASK) >> FLUID_INTERP_BITS_SHIFT)
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#define fluid_phase_double(_x) \
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((double)(fluid_phase_index(_x)) + ((double)fluid_phase_fract(_x) / FLUID_FRACT_MAX))
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/* Purpose:
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* Advance a by a step of b (both are fluid_phase_t).
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*/
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#define fluid_phase_incr(a, b) a += b
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/* Purpose:
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* Subtract b from a (both are fluid_phase_t).
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*/
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#define fluid_phase_decr(a, b) a -= b
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/* Purpose:
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* Subtract b samples from a.
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*/
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#define fluid_phase_sub_int(a, b) ((a) -= (unsigned long long)(b) << 32)
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/* Purpose:
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* Creates the expression a.index++. */
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#define fluid_phase_index_plusplus(a) (((a) += 0x100000000LL)
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#endif /* _FLUID_PHASE_H */
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