mirror of
https://github.com/dborth/snes9xgx.git
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116 lines
3.2 KiB
C++
116 lines
3.2 KiB
C++
/* Simple fixed-point linear resampler by BearOso*/
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#ifndef __LINEAR_RESAMPLER_H
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#define __LINEAR_RESAMPLER_H
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#include "resampler.h"
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#include "snes9x.h"
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static const int f_prec = 15;
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static const uint32 f__one = (1 << f_prec);
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#define lerp(t, a, b) (((((b) - (a)) * (t)) >> f_prec) + (a))
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class LinearResampler : public Resampler
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{
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protected:
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uint32 f__r_step;
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uint32 f__inv_r_step;
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uint32 f__r_frac;
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int r_left, r_right;
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public:
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LinearResampler (int num_samples) : Resampler (num_samples)
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{
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f__r_frac = 0;
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}
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~LinearResampler ()
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{
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}
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void
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time_ratio (double ratio)
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{
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if (ratio == 0.0)
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ratio = 1.0;
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f__r_step = (uint32) (ratio * f__one);
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f__inv_r_step = (uint32) (f__one / ratio);
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clear ();
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}
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void
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clear (void)
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{
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ring_buffer::clear ();
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f__r_frac = 0;
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r_left = 0;
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r_right = 0;
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}
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void
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read (short *data, int num_samples)
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{
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int i_position = start >> 1;
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short *internal_buffer = (short *) buffer;
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int o_position = 0;
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int consumed = 0;
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int max_samples = (buffer_size >> 1);
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while (o_position < num_samples && consumed < buffer_size)
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{
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if (f__r_step == f__one)
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{
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data[o_position] = internal_buffer[i_position];
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data[o_position + 1] = internal_buffer[i_position + 1];
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o_position += 2;
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i_position += 2;
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if (i_position >= max_samples)
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i_position -= max_samples;
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consumed += 2;
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continue;
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}
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while (f__r_frac <= f__one && o_position < num_samples)
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{
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data[o_position] = lerp (f__r_frac,
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r_left,
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internal_buffer[i_position]);
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data[o_position + 1] = lerp (f__r_frac,
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r_right,
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internal_buffer[i_position + 1]);
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o_position += 2;
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f__r_frac += f__r_step;
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}
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if (f__r_frac > f__one)
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{
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f__r_frac -= f__one;
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r_left = internal_buffer[i_position];
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r_right = internal_buffer[i_position + 1];
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i_position += 2;
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if (i_position >= max_samples)
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i_position -= max_samples;
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consumed += 2;
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}
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}
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size -= consumed << 1;
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start += consumed << 1;
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if (start >= buffer_size)
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start -= buffer_size;
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}
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inline int
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avail (void)
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{
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return (((size >> 2) * f__inv_r_step) - ((f__r_frac * f__inv_r_step) >> f_prec)) >> (f_prec - 1);
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}
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};
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#endif /* __LINEAR_RESAMPLER_H */
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