/*************************************************************************/
/*  audio_rb_resampler.cpp                                               */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
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/*                                                                       */
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/*************************************************************************/
#include "audio_rb_resampler.h"

int AudioRBResampler::get_channel_count() const {

	if (!rb)
		return 0;

	return channels;
}

template <int C>
uint32_t AudioRBResampler::_resample(int32_t *p_dest, int p_todo, int32_t p_increment) {

	uint32_t read = offset & MIX_FRAC_MASK;

	for (int i = 0; i < p_todo; i++) {

		offset = (offset + p_increment) & (((1 << (rb_bits + MIX_FRAC_BITS)) - 1));
		read += p_increment;
		uint32_t pos = offset >> MIX_FRAC_BITS;
		uint32_t frac = offset & MIX_FRAC_MASK;
#ifndef FAST_AUDIO
		ERR_FAIL_COND_V(pos >= rb_len, 0);
#endif
		uint32_t pos_next = (pos + 1) & rb_mask;
		//printf("rb pos %i\n",pos);

		// since this is a template with a known compile time value (C), conditionals go away when compiling.
		if (C == 1) {

			int32_t v0 = rb[pos];
			int32_t v0n = rb[pos_next];
#ifndef FAST_AUDIO
			v0 += (v0n - v0) * (int32_t)frac >> MIX_FRAC_BITS;
#endif
			v0 <<= 16;
			p_dest[i] = v0;
		}
		if (C == 2) {

			int32_t v0 = rb[(pos << 1) + 0];
			int32_t v1 = rb[(pos << 1) + 1];
			int32_t v0n = rb[(pos_next << 1) + 0];
			int32_t v1n = rb[(pos_next << 1) + 1];

#ifndef FAST_AUDIO
			v0 += (v0n - v0) * (int32_t)frac >> MIX_FRAC_BITS;
			v1 += (v1n - v1) * (int32_t)frac >> MIX_FRAC_BITS;
#endif
			v0 <<= 16;
			v1 <<= 16;
			p_dest[(i << 1) + 0] = v0;
			p_dest[(i << 1) + 1] = v1;
		}

		if (C == 4) {

			int32_t v0 = rb[(pos << 2) + 0];
			int32_t v1 = rb[(pos << 2) + 1];
			int32_t v2 = rb[(pos << 2) + 2];
			int32_t v3 = rb[(pos << 2) + 3];
			int32_t v0n = rb[(pos_next << 2) + 0];
			int32_t v1n = rb[(pos_next << 2) + 1];
			int32_t v2n = rb[(pos_next << 2) + 2];
			int32_t v3n = rb[(pos_next << 2) + 3];

#ifndef FAST_AUDIO
			v0 += (v0n - v0) * (int32_t)frac >> MIX_FRAC_BITS;
			v1 += (v1n - v1) * (int32_t)frac >> MIX_FRAC_BITS;
			v2 += (v2n - v2) * (int32_t)frac >> MIX_FRAC_BITS;
			v3 += (v3n - v3) * (int32_t)frac >> MIX_FRAC_BITS;
#endif
			v0 <<= 16;
			v1 <<= 16;
			v2 <<= 16;
			v3 <<= 16;
			p_dest[(i << 2) + 0] = v0;
			p_dest[(i << 2) + 1] = v1;
			p_dest[(i << 2) + 2] = v2;
			p_dest[(i << 2) + 3] = v3;
		}

		if (C == 6) {

			int32_t v0 = rb[(pos * 6) + 0];
			int32_t v1 = rb[(pos * 6) + 1];
			int32_t v2 = rb[(pos * 6) + 2];
			int32_t v3 = rb[(pos * 6) + 3];
			int32_t v4 = rb[(pos * 6) + 4];
			int32_t v5 = rb[(pos * 6) + 5];
			int32_t v0n = rb[(pos_next * 6) + 0];
			int32_t v1n = rb[(pos_next * 6) + 1];
			int32_t v2n = rb[(pos_next * 6) + 2];
			int32_t v3n = rb[(pos_next * 6) + 3];
			int32_t v4n = rb[(pos_next * 6) + 4];
			int32_t v5n = rb[(pos_next * 6) + 5];

#ifndef FAST_AUDIO
			v0 += (v0n - v0) * (int32_t)frac >> MIX_FRAC_BITS;
			v1 += (v1n - v1) * (int32_t)frac >> MIX_FRAC_BITS;
			v2 += (v2n - v2) * (int32_t)frac >> MIX_FRAC_BITS;
			v3 += (v3n - v3) * (int32_t)frac >> MIX_FRAC_BITS;
			v4 += (v4n - v4) * (int32_t)frac >> MIX_FRAC_BITS;
			v5 += (v5n - v5) * (int32_t)frac >> MIX_FRAC_BITS;
#endif
			v0 <<= 16;
			v1 <<= 16;
			v2 <<= 16;
			v3 <<= 16;
			v4 <<= 16;
			v5 <<= 16;
			p_dest[(i * 6) + 0] = v0;
			p_dest[(i * 6) + 1] = v1;
			p_dest[(i * 6) + 2] = v2;
			p_dest[(i * 6) + 3] = v3;
			p_dest[(i * 6) + 4] = v4;
			p_dest[(i * 6) + 5] = v5;
		}
	}

	return read >> MIX_FRAC_BITS; //rb_read_pos=offset>>MIX_FRAC_BITS;
}

bool AudioRBResampler::mix(int32_t *p_dest, int p_frames) {

	if (!rb)
		return false;

	int write_pos_cache = rb_write_pos;

	int32_t increment = (src_mix_rate * MIX_FRAC_LEN) / target_mix_rate;

	int rb_todo;

	if (write_pos_cache == rb_read_pos) {
		return false; //out of buffer

	} else if (rb_read_pos < write_pos_cache) {

		rb_todo = write_pos_cache - rb_read_pos; //-1?
	} else {

		rb_todo = (rb_len - rb_read_pos) + write_pos_cache; //-1?
	}

	int todo = MIN(((int64_t(rb_todo) << MIX_FRAC_BITS) / increment) + 1, p_frames);
#if 0
	if (int(src_mix_rate)==target_mix_rate) {


		if (channels==6) {

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

				int from = ((rb_read_pos+i)&rb_mask)*6;
				int to = i*6;

				p_dest[from+0]=int32_t(rb[to+0])<<16;
				p_dest[from+1]=int32_t(rb[to+1])<<16;
				p_dest[from+2]=int32_t(rb[to+2])<<16;
				p_dest[from+3]=int32_t(rb[to+3])<<16;
				p_dest[from+4]=int32_t(rb[to+4])<<16;
				p_dest[from+5]=int32_t(rb[to+5])<<16;
			}

		} else {
			int len=p_frames*channels;
			int from=rb_read_pos*channels;
			int mask=0;
			switch(channels) {
				case 1: mask=rb_len-1; break;
				case 2: mask=(rb_len*2)-1; break;
				case 4: mask=(rb_len*4)-1; break;
			}

			for(int i=0;i<len;i++) {

				p_dest[i]=int32_t(rb[(from+i)&mask])<<16;
			}
		}

		rb_read_pos = (rb_read_pos+p_frames)&rb_mask;
	} else
#endif
	{

		uint32_t read = 0;
		switch (channels) {
			case 1: read = _resample<1>(p_dest, todo, increment); break;
			case 2: read = _resample<2>(p_dest, todo, increment); break;
			case 4: read = _resample<4>(p_dest, todo, increment); break;
			case 6: read = _resample<6>(p_dest, todo, increment); break;
		}
#if 1
		//end of stream, fadeout
		int remaining = p_frames - todo;
		if (remaining && todo > 0) {

			//print_line("fadeout");
			for (int c = 0; c < channels; c++) {

				for (int i = 0; i < todo; i++) {

					int32_t samp = p_dest[i * channels + c] >> 8;
					uint32_t mul = (todo - i) * 256 / todo;
					//print_line("mul: "+itos(i)+" "+itos(mul));
					p_dest[i * channels + c] = samp * mul;
				}
			}
		}

#else
		int remaining = p_frames - todo;
		if (remaining && todo > 0) {

			for (int c = 0; c < channels; c++) {

				int32_t from = p_dest[(todo - 1) * channels + c] >> 8;

				for (int i = 0; i < remaining; i++) {

					uint32_t mul = (remaining - i) * 256 / remaining;
					p_dest[(todo + i) * channels + c] = from * mul;
				}
			}
		}
#endif

		//zero out what remains there to avoid glitches
		for (int i = todo * channels; i < int(p_frames) * channels; i++) {

			p_dest[i] = 0;
		}

		if (read > rb_todo)
			read = rb_todo;

		rb_read_pos = (rb_read_pos + read) & rb_mask;
	}

	return true;
}

Error AudioRBResampler::setup(int p_channels, int p_src_mix_rate, int p_target_mix_rate, int p_buffer_msec, int p_minbuff_needed) {

	ERR_FAIL_COND_V(p_channels != 1 && p_channels != 2 && p_channels != 4 && p_channels != 6, ERR_INVALID_PARAMETER);

	//float buffering_sec = int(GLOBAL_DEF("audio/stream_buffering_ms",500))/1000.0;
	int desired_rb_bits = nearest_shift(MAX((p_buffer_msec / 1000.0) * p_src_mix_rate, p_minbuff_needed));

	bool recreate = !rb;

	if (rb && (uint32_t(desired_rb_bits) != rb_bits || channels != uint32_t(p_channels))) {
		//recreate

		memdelete_arr(rb);
		memdelete_arr(read_buf);
		recreate = true;
	}

	if (recreate) {

		channels = p_channels;
		rb_bits = desired_rb_bits;
		rb_len = (1 << rb_bits);
		rb_mask = rb_len - 1;
		rb = memnew_arr(int16_t, rb_len * p_channels);
		read_buf = memnew_arr(int16_t, rb_len * p_channels);
	}

	src_mix_rate = p_src_mix_rate;
	target_mix_rate = p_target_mix_rate;
	offset = 0;
	rb_read_pos = 0;
	rb_write_pos = 0;

	//avoid maybe strange noises upon load
	for (int i = 0; i < (rb_len * channels); i++) {

		rb[i] = 0;
		read_buf[i] = 0;
	}

	return OK;
}

void AudioRBResampler::clear() {

	if (!rb)
		return;

	//should be stopped at this point but just in case
	if (rb) {
		memdelete_arr(rb);
		memdelete_arr(read_buf);
	}
	rb = NULL;
	offset = 0;
	rb_read_pos = 0;
	rb_write_pos = 0;
	read_buf = NULL;
}

AudioRBResampler::AudioRBResampler() {

	rb = NULL;
	offset = 0;
	read_buf = NULL;
	rb_read_pos = 0;
	rb_write_pos = 0;

	rb_bits = 0;
	rb_len = 0;
	rb_mask = 0;
	read_buff_len = 0;
	channels = 0;
	src_mix_rate = 0;
	target_mix_rate = 0;
}

AudioRBResampler::~AudioRBResampler() {

	if (rb) {
		memdelete_arr(rb);
		memdelete_arr(read_buf);
	}
}