godot/servers/audio/audio_rb_resampler.h

#ifndef AUDIO_RB_RESAMPLER_H
#define AUDIO_RB_RESAMPLER_H

#include "typedefs.h"
#include "os/memory.h"

struct AudioRBResampler {

	uint32_t rb_bits;
	uint32_t rb_len;
	uint32_t rb_mask;
	uint32_t read_buff_len;
	uint32_t channels;
	uint32_t src_mix_rate;
	uint32_t target_mix_rate;

	volatile int rb_read_pos;
	volatile int rb_write_pos;

	int32_t offset; //contains the fractional remainder of the resampler
	enum {
		MIX_FRAC_BITS=13,
		MIX_FRAC_LEN=(1<<MIX_FRAC_BITS),
		MIX_FRAC_MASK=MIX_FRAC_LEN-1,
	};

	int16_t *read_buf;
	int16_t *rb;


	template<int C>
	uint32_t _resample(int32_t *p_dest,int p_todo,int32_t p_increment);


public:

	_FORCE_INLINE_ void flush() {
		rb_read_pos=0;
		rb_write_pos=0;
	}

	_FORCE_INLINE_ bool is_ready() const{
		return rb!=NULL;
	}


	_FORCE_INLINE_ int get_total() const {

		return rb_len-1;
	}

	_FORCE_INLINE_ int get_todo() const { //return amount of frames to mix

		int todo;
		int read_pos_cache=rb_read_pos;

		if (read_pos_cache==rb_write_pos) {
			todo=rb_len-1;
		} else if (read_pos_cache>rb_write_pos) {

			todo=read_pos_cache-rb_write_pos-1;
		} else {

			todo=(rb_len-rb_write_pos)+read_pos_cache-1;
		}

		return todo;
	}

	_FORCE_INLINE_ int16_t *get_write_buffer() { return read_buf; }
	_FORCE_INLINE_ void write(uint32_t p_frames) {

		ERR_FAIL_COND(p_frames >= rb_len);

		switch(channels) {
			case 1: {

				for(uint32_t i=0;i<p_frames;i++) {

					rb[ rb_write_pos ] = read_buf[i];
					rb_write_pos=(rb_write_pos+1)&rb_mask;
				}
			} break;
			case 2: {

				for(uint32_t i=0;i<p_frames;i++) {

					rb[ (rb_write_pos<<1)+0 ] = read_buf[(i<<1)+0];
					rb[ (rb_write_pos<<1)+1 ] = read_buf[(i<<1)+1];
					rb_write_pos=(rb_write_pos+1)&rb_mask;
				}
			} break;
			case 4: {

				for(uint32_t i=0;i<p_frames;i++) {

					rb[ (rb_write_pos<<2)+0 ] = read_buf[(i<<2)+0];
					rb[ (rb_write_pos<<2)+1 ] = read_buf[(i<<2)+1];
					rb[ (rb_write_pos<<2)+2 ] = read_buf[(i<<2)+2];
					rb[ (rb_write_pos<<2)+3 ] = read_buf[(i<<2)+3];
					rb_write_pos=(rb_write_pos+1)&rb_mask;
				}
			} break;
			case 6: {

				for(uint32_t i=0;i<p_frames;i++) {

					rb[ (rb_write_pos*6)+0 ] = read_buf[(i*6)+0];
					rb[ (rb_write_pos*6)+1 ] = read_buf[(i*6)+1];
					rb[ (rb_write_pos*6)+2 ] = read_buf[(i*6)+2];
					rb[ (rb_write_pos*6)+3 ] = read_buf[(i*6)+3];
					rb[ (rb_write_pos*6)+4 ] = read_buf[(i*6)+4];
					rb[ (rb_write_pos*6)+5 ] = read_buf[(i*6)+5];
					rb_write_pos=(rb_write_pos+1)&rb_mask;
				}
			} break;


		}

	}

	int get_channel_count() const;

	Error setup(int p_channels, int p_src_mix_rate, int p_target_mix_rate, int p_buffer_msec, int p_minbuff_needed=-1);
	void clear();
	bool mix(int32_t *p_dest, int p_frames);

	AudioRBResampler();
	~AudioRBResampler();
};

#endif // AUDIO_RB_RESAMPLER_H