/*
 * ALAC (Apple Lossless Audio Codec) decoder
 * Copyright (c) 2005 David Hammerton
 * All rights reserved.
 *
 * This is the actual decoder.
 *
 * http://crazney.net/programs/itunes/alac.html
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
	#include "stdint_win.h"
#else
	#include <stdint.h>
#endif

#include "decomp.h"
#include "esp_log.h"

static const char *TAG = "alac_decoder";

struct {signed int x:24;} se_struct_24;
#define SignExtend24(val) (se_struct_24.x = val)

void alac_set_info(alac_file *alac, char *inputbuffer)
{
	char *ptr = inputbuffer;
	alac->setinfo_max_samples_per_frame = __builtin_bswap32(*(uint32_t*)ptr); /* buffer size / 2 ? */
	ptr += 4;
	alac->setinfo_7a = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_sample_size = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_rice_historymult = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_rice_initialhistory = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_rice_kmodifier = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_7f = *(uint8_t*)ptr;
	ptr += 1;
	alac->setinfo_80 = __builtin_bswap16(*(uint16_t*)ptr);
	ptr += 2;
	alac->setinfo_82 = __builtin_bswap32(*(uint32_t*)ptr);
	ptr += 4;
	alac->setinfo_86 = __builtin_bswap32(*(uint32_t*)ptr);
	ptr += 4;
	alac->setinfo_8a_rate = __builtin_bswap32(*(uint32_t*)ptr);
	ptr += 4;

	//allocate_buffers(alac);

}

/* stream reading */

/* supports reading 1 to 16 bits, in big endian format */
static uint32_t readbits_16(alac_file *alac, int bits)
{
	uint32_t result;
	int new_accumulator;

	result = (alac->input_buffer[0] << 16) |
			 (alac->input_buffer[1] << 8) |
			 (alac->input_buffer[2]);

	/* shift left by the number of bits we've already read,
	 * so that the top 'n' bits of the 24 bits we read will
	 * be the return bits */
	result = result << alac->input_buffer_bitaccumulator;

	result = result & 0x00ffffff;

	/* and then only want the top 'n' bits from that, where
	 * n is 'bits' */
	result = result >> (24 - bits);

	new_accumulator = (alac->input_buffer_bitaccumulator + bits);

	/* increase the buffer pointer if we've read over n bytes. */
	alac->input_buffer += (new_accumulator >> 3);

	/* and the remainder goes back into the bit accumulator */
	alac->input_buffer_bitaccumulator = (new_accumulator & 7);

	return result;
}

/* supports reading 1 to 32 bits, in big endian format */
static uint32_t readbits(alac_file *alac, int bits)
{
	int32_t result = 0;

	if (bits > 16)
	{
		bits -= 16;
		result = readbits_16(alac, 16) << bits;
	}

	result |= readbits_16(alac, bits);

	return result;
}

/* reads a single bit */
static int readbit(alac_file *alac)
{
	int result;
	int new_accumulator;

	result = alac->input_buffer[0];

	result = result << alac->input_buffer_bitaccumulator;

	result = result >> 7 & 1;

	new_accumulator = (alac->input_buffer_bitaccumulator + 1);

	alac->input_buffer += (new_accumulator / 8);

	alac->input_buffer_bitaccumulator = (new_accumulator % 8);

	return result;
}

static void unreadbits(alac_file *alac, int bits)
{
	int new_accumulator = (alac->input_buffer_bitaccumulator - bits);

	alac->input_buffer += (new_accumulator >> 3);

	alac->input_buffer_bitaccumulator = (new_accumulator & 7);
	if (alac->input_buffer_bitaccumulator < 0)
		alac->input_buffer_bitaccumulator *= -1;
}

static int count_leading_zeros(int input)
{
	if(input == 0)
		return 32;
	return __builtin_clz(input);
}

#define RICE_THRESHOLD 8 // maximum number of bits for a rice prefix.

int32_t entropy_decode_value(alac_file* alac,
							 int readSampleSize,
							 int k,
							 int rice_kmodifier_mask)
{
	int32_t x = 0; // decoded value

	// read x, number of 1s before 0 represent the rice value.
	while (x <= RICE_THRESHOLD && readbit(alac))
	{
		x++;
	}

	if (x > RICE_THRESHOLD)
	{
		// read the number from the bit stream (raw value)
		int32_t value;

		value = readbits(alac, readSampleSize);

		// mask value
		value &= (((uint32_t)0xffffffff) >> (32 - readSampleSize));

		x = value;
	}
	else
	{
		if (k != 1)
		{
			int extraBits = readbits(alac, k);

			// x = x * (2^k - 1)
			x *= (((1 << k) - 1) & rice_kmodifier_mask);

			if (extraBits > 1)
				x += extraBits - 1;
			else
				unreadbits(alac, 1);
		}
	}

	return x;
}

void entropy_rice_decode(alac_file* alac,
						 int32_t* outputBuffer,
						 int outputSize,
						 int readSampleSize,
						 int rice_initialhistory,
						 int rice_kmodifier,
						 int rice_historymult,
						 int rice_kmodifier_mask)
{
	int outputCount;
	int history = rice_initialhistory;
	int signModifier = 0;

	for (outputCount = 0; outputCount < outputSize; outputCount++)
	{
		int32_t decodedValue;
		int32_t finalValue;
		int32_t k;

		k = 31 - rice_kmodifier - count_leading_zeros((history >> 9) + 3);

		if (k < 0) k += rice_kmodifier;
		else k = rice_kmodifier;

		// note: don't use rice_kmodifier_mask here (set mask to 0xFFFFFFFF)
		decodedValue = entropy_decode_value(alac, readSampleSize, k, 0xFFFFFFFF);

		decodedValue += signModifier;
		finalValue = (decodedValue + 1) / 2; // inc by 1 and shift out sign bit
		if (decodedValue & 1) // the sign is stored in the low bit
			finalValue *= -1;

		outputBuffer[outputCount] = finalValue;

		signModifier = 0;

		// update history
		history += (decodedValue * rice_historymult)
				- ((history * rice_historymult) >> 9);

		if (decodedValue > 0xFFFF)
			history = 0xFFFF;

		// special case, for compressed blocks of 0
		if ((history < 128) && (outputCount + 1 < outputSize))
		{
			int32_t		blockSize;

			signModifier = 1;

			k = count_leading_zeros(history) + ((history + 16) / 64) - 24;

			// note: blockSize is always 16bit
			blockSize = entropy_decode_value(alac, 16, k, rice_kmodifier_mask);

			// got blockSize 0s
			if (blockSize > 0)
			{
				memset(&outputBuffer[outputCount + 1], 0, blockSize * sizeof(*outputBuffer));
				outputCount += blockSize;
			}

			if (blockSize > 0xFFFF)
				signModifier = 0;

			history = 0;
		}
	}
}

#define SIGN_EXTENDED32(val, bits) ((val << (32 - bits)) >> (32 - bits))

#define SIGN_ONLY(v) \
	((v < 0) ? (-1) : \
		((v > 0) ? (1) : \
			(0)))

static void predictor_decompress_fir_adapt(int32_t *error_buffer,
										   int32_t *buffer_out,
										   int output_size,
										   int readsamplesize,
										   int16_t *predictor_coef_table,
										   int predictor_coef_num,
										   int predictor_quantitization)
{
	int i;

	/* first sample always copies */
	*buffer_out = *error_buffer;

	if (!predictor_coef_num)
	{
		if (output_size <= 1) return;
		memcpy(buffer_out+1, error_buffer+1, (output_size-1) * 4);
		return;
	}

	if (predictor_coef_num == 0x1f) /* 11111 - max value of predictor_coef_num */
	{ /* second-best case scenario for fir decompression,
	   * error describes a small difference from the previous sample only
	   */
		if (output_size <= 1) return;
		for (i = 0; i < output_size - 1; i++)
		{
			int32_t prev_value;
			int32_t error_value;

			prev_value = buffer_out[i];
			error_value = error_buffer[i+1];
			buffer_out[i+1] = SIGN_EXTENDED32((prev_value + error_value), readsamplesize);
		}
		return;
	}

	/* read warm-up samples */
	if (predictor_coef_num > 0)
	{
		int i;
		for (i = 0; i < predictor_coef_num; i++)
		{
			int32_t val;

			val = buffer_out[i] + error_buffer[i+1];

			val = SIGN_EXTENDED32(val, readsamplesize);

			buffer_out[i+1] = val;
		}
	}

#if 0
	/* 4 and 8 are very common cases (the only ones i've seen). these
	 * should be unrolled and optimised
	 */
	if (predictor_coef_num == 4)
	{
		/* FIXME: optimised general case */
		return;
	}

	if (predictor_coef_table == 8)
	{
		/* FIXME: optimised general case */
		return;
	}
#endif

	/* general case */
	if (predictor_coef_num > 0)
	{
		for (i = predictor_coef_num + 1;
			 i < output_size;
			 i++)
		{
			int j;
			int sum = 0;
			int outval;
			int error_val = error_buffer[i];

			for (j = 0; j < predictor_coef_num; j++)
			{
				sum += (buffer_out[predictor_coef_num-j] - buffer_out[0]) *
					   predictor_coef_table[j];
			}

			outval = (1 << (predictor_quantitization-1)) + sum;
			outval = outval >> predictor_quantitization;
			outval = outval + buffer_out[0] + error_val;
			outval = SIGN_EXTENDED32(outval, readsamplesize);

			buffer_out[predictor_coef_num+1] = outval;

			if (error_val > 0)
			{
				int predictor_num = predictor_coef_num - 1;

				while (predictor_num >= 0 && error_val > 0)
				{
					int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
					int sign = SIGN_ONLY(val);

					predictor_coef_table[predictor_num] -= sign;

					val *= sign; /* absolute value */

					error_val -= ((val >> predictor_quantitization) *
								  (predictor_coef_num - predictor_num));

					predictor_num--;
				}
			}
			else if (error_val < 0)
			{
				int predictor_num = predictor_coef_num - 1;

				while (predictor_num >= 0 && error_val < 0)
				{
					int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
					int sign = - SIGN_ONLY(val);

					predictor_coef_table[predictor_num] -= sign;

					val *= sign; /* neg value */

					error_val -= ((val >> predictor_quantitization) *
								  (predictor_coef_num - predictor_num));

					predictor_num--;
				}
			}

			buffer_out++;
		}
	}
}

void deinterlace_16(int32_t *buffer_a, int32_t *buffer_b,
					int16_t *buffer_out,
					int numchannels, int numsamples,
					uint8_t interlacing_shift,
					uint8_t interlacing_leftweight)
{
	int i;
	if (numsamples <= 0) return;

	/* weighted interlacing */
	if (interlacing_leftweight)
	{
		for (i = 0; i < numsamples; i++)
		{
			int32_t difference, midright;
			int16_t left;
			int16_t right;

			midright = buffer_a[i];
			difference = buffer_b[i];

			right = midright - ((difference * interlacing_leftweight) >> interlacing_shift);
			left = right + difference;

			buffer_out[i*numchannels] = left;
			buffer_out[i*numchannels + 1] = right;
		}

		return;
	}

	/* otherwise basic interlacing took place */
	for (i = 0; i < numsamples; i++)
	{
		int16_t left, right;

		left = buffer_a[i];
		right = buffer_b[i];

		buffer_out[i*numchannels] = left;
		buffer_out[i*numchannels + 1] = right;
	}
}

void deinterlace_24(int32_t *buffer_a, int32_t *buffer_b,
					int uncompressed_bytes,
					int32_t *uncompressed_bytes_buffer_a, int32_t *uncompressed_bytes_buffer_b,
					void *buffer_out,
					int numchannels, int numsamples,
					uint8_t interlacing_shift,
					uint8_t interlacing_leftweight)
{
	int i;
	if (numsamples <= 0) return;

	/* weighted interlacing */
	if (interlacing_leftweight)
	{
		for (i = 0; i < numsamples; i++)
		{
			int32_t difference, midright;
			int32_t left;
			int32_t right;

			midright = buffer_a[i];
			difference = buffer_b[i];

			right = midright - ((difference * interlacing_leftweight) >> interlacing_shift);
			left = right + difference;

			if (uncompressed_bytes)
			{
				uint32_t mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
				left <<= (uncompressed_bytes * 8);
				right <<= (uncompressed_bytes * 8);

				left |= uncompressed_bytes_buffer_a[i] & mask;
				right |= uncompressed_bytes_buffer_b[i] & mask;
			}

			((uint8_t*)buffer_out)[i * numchannels * 3] = (left) & 0xFF;
			((uint8_t*)buffer_out)[i * numchannels * 3 + 1] = (left >> 8) & 0xFF;
			((uint8_t*)buffer_out)[i * numchannels * 3 + 2] = (left >> 16) & 0xFF;

			((uint8_t*)buffer_out)[i * numchannels * 3 + 3] = (right) & 0xFF;
			((uint8_t*)buffer_out)[i * numchannels * 3 + 4] = (right >> 8) & 0xFF;
			((uint8_t*)buffer_out)[i * numchannels * 3 + 5] = (right >> 16) & 0xFF;
		}

		return;
	}

	/* otherwise basic interlacing took place */
	for (i = 0; i < numsamples; i++)
	{
		int32_t left, right;

		left = buffer_a[i];
		right = buffer_b[i];

		if (uncompressed_bytes)
		{
			uint32_t mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
			left <<= (uncompressed_bytes * 8);
			right <<= (uncompressed_bytes * 8);

			left |= uncompressed_bytes_buffer_a[i] & mask;
			right |= uncompressed_bytes_buffer_b[i] & mask;
		}

		((uint8_t*)buffer_out)[i * numchannels * 3] = (left) & 0xFF;
		((uint8_t*)buffer_out)[i * numchannels * 3 + 1] = (left >> 8) & 0xFF;
		((uint8_t*)buffer_out)[i * numchannels * 3 + 2] = (left >> 16) & 0xFF;

		((uint8_t*)buffer_out)[i * numchannels * 3 + 3] = (right) & 0xFF;
		((uint8_t*)buffer_out)[i * numchannels * 3 + 4] = (right >> 8) & 0xFF;
		((uint8_t*)buffer_out)[i * numchannels * 3 + 5] = (right >> 16) & 0xFF;

	}

}

int decode_frame(alac_file *alac,
				  unsigned char *inbuffer,
				  void *outbuffer, int *outputsize)
{
	int channels;
	int32_t outputsamples = alac->setinfo_max_samples_per_frame;

	/* setup the stream */
	alac->input_buffer = inbuffer;
	alac->input_buffer_bitaccumulator = 0;

	channels = readbits(alac, 3);

	*outputsize = outputsamples * alac->bytespersample;

	switch(channels)
	{
	case 0: /* 1 channel */
	{
		int hassize;
		int isnotcompressed;
		int readsamplesize;

		int uncompressed_bytes;
		int ricemodifier;

		/* 2^result = something to do with output waiting.
		 * perhaps matters if we read > 1 frame in a pass?
		 */
		readbits(alac, 4);

		readbits(alac, 12); /* unknown, skip 12 bits */

		hassize = readbits(alac, 1); /* the output sample size is stored soon */

		uncompressed_bytes = readbits(alac, 2); /* number of bytes in the (compressed) stream that are not compressed */

		isnotcompressed = readbits(alac, 1); /* whether the frame is compressed */

		if (hassize)
		{
			/* now read the number of samples,
			 * as a 32bit integer */
			outputsamples = readbits(alac, 32);
			*outputsize = outputsamples * alac->bytespersample;
		}

		readsamplesize = alac->setinfo_sample_size - (uncompressed_bytes * 8);

		if (!isnotcompressed)
		{ /* so it is compressed */
			int16_t predictor_coef_table[32];
			int predictor_coef_num;
			int prediction_type;
			int prediction_quantitization;
			int i;

			/* skip 16 bits, not sure what they are. seem to be used in
			 * two channel case */
			readbits(alac, 8);
			readbits(alac, 8);

			prediction_type = readbits(alac, 4);
			prediction_quantitization = readbits(alac, 4);

			ricemodifier = readbits(alac, 3);
			predictor_coef_num = readbits(alac, 5);

			/* read the predictor table */
			for (i = 0; i < predictor_coef_num; i++)
			{
				predictor_coef_table[i] = (int16_t)readbits(alac, 16);
			}

			if (uncompressed_bytes)
			{
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					alac->uncompressed_bytes_buffer_a[i] = readbits(alac, uncompressed_bytes * 8);
				}
			}

			entropy_rice_decode(alac,
								alac->predicterror_buffer_a,
								outputsamples,
								readsamplesize,
								alac->setinfo_rice_initialhistory,
								alac->setinfo_rice_kmodifier,
								ricemodifier * alac->setinfo_rice_historymult / 4,
								(1 << alac->setinfo_rice_kmodifier) - 1);

			if (prediction_type == 0)
			{ /* adaptive fir */
				predictor_decompress_fir_adapt(alac->predicterror_buffer_a,
											   alac->outputsamples_buffer_a,
											   outputsamples,
											   readsamplesize,
											   predictor_coef_table,
											   predictor_coef_num,
											   prediction_quantitization);
			}
			else
			{
				ESP_LOGE(TAG, "FIXME: unhandled predicition type: %i", prediction_type);
				/* i think the only other prediction type (or perhaps this is just a
				 * boolean?) runs adaptive fir twice.. like:
				 * predictor_decompress_fir_adapt(predictor_error, tempout, ...)
				 * predictor_decompress_fir_adapt(predictor_error, outputsamples ...)
				 * little strange..
				 */
				return 0;
			}

		}
		else
		{ /* not compressed, easy case */
			if (alac->setinfo_sample_size <= 16)
			{
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					int32_t audiobits = readbits(alac, alac->setinfo_sample_size);

					audiobits = SIGN_EXTENDED32(audiobits, alac->setinfo_sample_size);

					alac->outputsamples_buffer_a[i] = audiobits;
				}
			}
			else
			{
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					int32_t audiobits;

					audiobits = readbits(alac, 16);
					/* special case of sign extension..
					 * as we'll be ORing the low 16bits into this */
					audiobits = audiobits << (alac->setinfo_sample_size - 16);
					audiobits |= readbits(alac, alac->setinfo_sample_size - 16);
					audiobits = SignExtend24(audiobits);

					alac->outputsamples_buffer_a[i] = audiobits;
				}
			}
			uncompressed_bytes = 0; // always 0 for uncompressed
		}

		switch(alac->setinfo_sample_size)
		{
		case 16:
		{
			int i;
			for (i = 0; i < outputsamples; i++)
			{
				int16_t sample = alac->outputsamples_buffer_a[i];
				((int16_t*)outbuffer)[i * alac->numchannels] = sample;
			}
			break;
		}
		case 24:
		{
			int i;
			for (i = 0; i < outputsamples; i++)
			{
				int32_t sample = alac->outputsamples_buffer_a[i];

				if (uncompressed_bytes)
				{
					uint32_t mask;
					sample = sample << (uncompressed_bytes * 8);
					mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
					sample |= alac->uncompressed_bytes_buffer_a[i] & mask;
				}

				((uint8_t*)outbuffer)[i * alac->numchannels * 3] = (sample) & 0xFF;
				((uint8_t*)outbuffer)[i * alac->numchannels * 3 + 1] = (sample >> 8) & 0xFF;
				((uint8_t*)outbuffer)[i * alac->numchannels * 3 + 2] = (sample >> 16) & 0xFF;
			}
			break;
		}
		case 20:
		case 32:
			ESP_LOGE(TAG, "FIXME: unimplemented sample size %i", alac->setinfo_sample_size);
			return 0;
		default:
			break;
		}
		break;
	}
	case 1: /* 2 channels */
	{
		int hassize;
		int isnotcompressed;
		int readsamplesize;

		int uncompressed_bytes;

		uint8_t interlacing_shift;
		uint8_t interlacing_leftweight;

		/* 2^result = something to do with output waiting.
		 * perhaps matters if we read > 1 frame in a pass?
		 */
		readbits(alac, 4);

		readbits(alac, 12); /* unknown, skip 12 bits */

		hassize = readbits(alac, 1); /* the output sample size is stored soon */

		uncompressed_bytes = readbits(alac, 2); /* the number of bytes in the (compressed) stream that are not compressed */

		isnotcompressed = readbits(alac, 1); /* whether the frame is compressed */

		if (hassize)
		{
			/* now read the number of samples,
			 * as a 32bit integer */
			outputsamples = readbits(alac, 32);
			*outputsize = outputsamples * alac->bytespersample;
		}

		readsamplesize = alac->setinfo_sample_size - (uncompressed_bytes * 8) + 1;

		if (!isnotcompressed)
		{ /* compressed */
			int16_t predictor_coef_table_a[32];
			int predictor_coef_num_a;
			int prediction_type_a;
			int prediction_quantitization_a;
			int ricemodifier_a;

			int16_t predictor_coef_table_b[32];
			int predictor_coef_num_b;
			int prediction_type_b;
			int prediction_quantitization_b;
			int ricemodifier_b;

			int i;

			interlacing_shift = readbits(alac, 8);
			interlacing_leftweight = readbits(alac, 8);

			/******** channel 1 ***********/
			prediction_type_a = readbits(alac, 4);
			prediction_quantitization_a = readbits(alac, 4);

			ricemodifier_a = readbits(alac, 3);
			predictor_coef_num_a = readbits(alac, 5);

			/* read the predictor table */
			for (i = 0; i < predictor_coef_num_a; i++)
			{
				predictor_coef_table_a[i] = (int16_t)readbits(alac, 16);
			}

			/******** channel 2 *********/
			prediction_type_b = readbits(alac, 4);
			prediction_quantitization_b = readbits(alac, 4);

			ricemodifier_b = readbits(alac, 3);
			predictor_coef_num_b = readbits(alac, 5);

			/* read the predictor table */
			for (i = 0; i < predictor_coef_num_b; i++)
			{
				predictor_coef_table_b[i] = (int16_t)readbits(alac, 16);
			}

			/*********************/
			if (uncompressed_bytes)
			{ /* see mono case */
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					alac->uncompressed_bytes_buffer_a[i] = readbits(alac, uncompressed_bytes * 8);
					alac->uncompressed_bytes_buffer_b[i] = readbits(alac, uncompressed_bytes * 8);
				}
			}

			/* channel 1 */
			entropy_rice_decode(alac,
								alac->predicterror_buffer_a,
								outputsamples,
								readsamplesize,
								alac->setinfo_rice_initialhistory,
								alac->setinfo_rice_kmodifier,
								ricemodifier_a * alac->setinfo_rice_historymult / 4,
								(1 << alac->setinfo_rice_kmodifier) - 1);

			if (prediction_type_a == 0)
			{ /* adaptive fir */
				predictor_decompress_fir_adapt(alac->predicterror_buffer_a,
											   alac->outputsamples_buffer_a,
											   outputsamples,
											   readsamplesize,
											   predictor_coef_table_a,
											   predictor_coef_num_a,
											   prediction_quantitization_a);
			}
			else
			{ /* see mono case */
				ESP_LOGE(TAG, "FIXME: unhandled predicition type: %i", prediction_type_a);
				return 0;
			}

			/* channel 2 */
			entropy_rice_decode(alac,
								alac->predicterror_buffer_b,
								outputsamples,
								readsamplesize,
								alac->setinfo_rice_initialhistory,
								alac->setinfo_rice_kmodifier,
								ricemodifier_b * alac->setinfo_rice_historymult / 4,
								(1 << alac->setinfo_rice_kmodifier) - 1);

			if (prediction_type_b == 0)
			{ /* adaptive fir */
				predictor_decompress_fir_adapt(alac->predicterror_buffer_b,
											   alac->outputsamples_buffer_b,
											   outputsamples,
											   readsamplesize,
											   predictor_coef_table_b,
											   predictor_coef_num_b,
											   prediction_quantitization_b);
			}
			else
			{
				ESP_LOGE(TAG, "FIXME: unhandled predicition type: %i", prediction_type_b);
				return 0;
			}
		}
		else
		{ /* not compressed, easy case */
			if (alac->setinfo_sample_size <= 16)
			{
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					int32_t audiobits_a, audiobits_b;

					audiobits_a = readbits(alac, alac->setinfo_sample_size);
					audiobits_b = readbits(alac, alac->setinfo_sample_size);

					audiobits_a = SIGN_EXTENDED32(audiobits_a, alac->setinfo_sample_size);
					audiobits_b = SIGN_EXTENDED32(audiobits_b, alac->setinfo_sample_size);

					alac->outputsamples_buffer_a[i] = audiobits_a;
					alac->outputsamples_buffer_b[i] = audiobits_b;
				}
			}
			else
			{
				int i;
				for (i = 0; i < outputsamples; i++)
				{
					int32_t audiobits_a, audiobits_b;

					audiobits_a = readbits(alac, 16);
					audiobits_a = audiobits_a << (alac->setinfo_sample_size - 16);
					audiobits_a |= readbits(alac, alac->setinfo_sample_size - 16);
					audiobits_a = SignExtend24(audiobits_a);

					audiobits_b = readbits(alac, 16);
					audiobits_b = audiobits_b << (alac->setinfo_sample_size - 16);
					audiobits_b |= readbits(alac, alac->setinfo_sample_size - 16);
					audiobits_b = SignExtend24(audiobits_b);

					alac->outputsamples_buffer_a[i] = audiobits_a;
					alac->outputsamples_buffer_b[i] = audiobits_b;
				}
			}
			uncompressed_bytes = 0; // always 0 for uncompressed
			interlacing_shift = 0;
			interlacing_leftweight = 0;
		}

		switch(alac->setinfo_sample_size)
		{
		case 16:
		{
			deinterlace_16(alac->outputsamples_buffer_a,
						   alac->outputsamples_buffer_b,
						   (int16_t*)outbuffer,
						   alac->numchannels,
						   outputsamples,
						   interlacing_shift,
						   interlacing_leftweight);
			break;
		}
		case 24:
		{
			deinterlace_24(alac->outputsamples_buffer_a,
						   alac->outputsamples_buffer_b,
						   uncompressed_bytes,
						   alac->uncompressed_bytes_buffer_a,
						   alac->uncompressed_bytes_buffer_b,
						   (int16_t*)outbuffer,
						   alac->numchannels,
						   outputsamples,
						   interlacing_shift,
						   interlacing_leftweight);
			break;
		}
		case 20:
		case 32:
			ESP_LOGE(TAG, "FIXME: unimplemented sample size %i", alac->setinfo_sample_size);
			return 0;
		default:
			break;
		}

		break;
	}
	}
	return 1;
}

void create_alac(alac_file *alac, int samplesize, int numchannels)
{
	alac->samplesize = samplesize;
	alac->numchannels = numchannels;
	alac->bytespersample = (samplesize / 8) * numchannels;
}
