/*
  * TTA (The Lossless True Audio) decoder
  * Copyright (c) 2006 Alex Beregszaszi
  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */
 
 /**

  * @file libavcodec/tta.c

  * TTA (The Lossless True Audio) decoder
  * (www.true-audio.com or tta.corecodec.org)
  * @author Alex Beregszaszi
  *
  */
 
 #define ALT_BITSTREAM_READER_LE
 //#define DEBUG
 #include <limits.h>
 #include "avcodec.h"
 #include "bitstream.h"
 
 #define FORMAT_INT 1
 #define FORMAT_FLOAT 3
 
 typedef struct TTAContext {
     AVCodecContext *avctx;
     GetBitContext gb;
 
     int flags, channels, bps, is_float, data_length;
     int frame_length, last_frame_length, total_frames;
 

     int32_t *decode_buffer;

 } TTAContext;
 
 #if 0
 static inline int shift_1(int i)
 {
     if (i < 32)
         return 1 << i;
     else
         return 0x80000000; // 16 << 31
 }
 
 static inline int shift_16(int i)
 {
     if (i < 28)
         return 16 << i;
     else
         return 0x80000000; // 16 << 27
 }
 #else

 static const uint32_t shift_1[] = {

     0x00000001, 0x00000002, 0x00000004, 0x00000008,
     0x00000010, 0x00000020, 0x00000040, 0x00000080,
     0x00000100, 0x00000200, 0x00000400, 0x00000800,
     0x00001000, 0x00002000, 0x00004000, 0x00008000,
     0x00010000, 0x00020000, 0x00040000, 0x00080000,
     0x00100000, 0x00200000, 0x00400000, 0x00800000,
     0x01000000, 0x02000000, 0x04000000, 0x08000000,
     0x10000000, 0x20000000, 0x40000000, 0x80000000,
     0x80000000, 0x80000000, 0x80000000, 0x80000000,
     0x80000000, 0x80000000, 0x80000000, 0x80000000
 };
 

 static const uint32_t * const shift_16 = shift_1 + 4;

 #endif
 
 #define MAX_ORDER 16
 typedef struct TTAFilter {

     int32_t shift, round, error, mode;
     int32_t qm[MAX_ORDER];
     int32_t dx[MAX_ORDER];
     int32_t dl[MAX_ORDER];

 } TTAFilter;
 

 static const int32_t ttafilter_configs[4][2] = {

     {10, 1},
     {9, 1},
     {10, 1},
     {12, 0}
 };
 

 static void ttafilter_init(TTAFilter *c, int32_t shift, int32_t mode) {

     memset(c, 0, sizeof(TTAFilter));
     c->shift = shift;
    c->round = shift_1[shift-1];
 //    c->round = 1 << (shift - 1);
     c->mode = mode;
 }
 
 // FIXME: copy paste from original

 static inline void memshl(register int32_t *a, register int32_t *b) {

     *a++ = *b++;
     *a++ = *b++;
     *a++ = *b++;
     *a++ = *b++;
     *a++ = *b++;
     *a++ = *b++;
     *a++ = *b++;
     *a = *b;
 }
 
 // FIXME: copy paste from original
 // mode=1 encoder, mode=0 decoder

 static inline void ttafilter_process(TTAFilter *c, int32_t *in, int32_t mode) {
     register int32_t *dl = c->dl, *qm = c->qm, *dx = c->dx, sum = c->round;

 
     if (!c->error) {
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         sum += *dl++ * *qm, qm++;
         dx += 8;
     } else if(c->error < 0) {
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
         sum += *dl++ * (*qm -= *dx++), qm++;
     } else {
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
         sum += *dl++ * (*qm += *dx++), qm++;
     }
 
     *(dx-0) = ((*(dl-1) >> 30) | 1) << 2;
     *(dx-1) = ((*(dl-2) >> 30) | 1) << 1;
     *(dx-2) = ((*(dl-3) >> 30) | 1) << 1;
     *(dx-3) = ((*(dl-4) >> 30) | 1);
 
     // compress
     if (mode) {
         *dl = *in;
         *in -= (sum >> c->shift);
         c->error = *in;
     } else {
         c->error = *in;
         *in += (sum >> c->shift);
         *dl = *in;
     }
 
     if (c->mode) {
         *(dl-1) = *dl - *(dl-1);
         *(dl-2) = *(dl-1) - *(dl-2);
         *(dl-3) = *(dl-2) - *(dl-3);
     }
 
     memshl(c->dl, c->dl + 1);
     memshl(c->dx, c->dx + 1);
 }
 
 typedef struct TTARice {

     uint32_t k0, k1, sum0, sum1;

 } TTARice;
 

 static void rice_init(TTARice *c, uint32_t k0, uint32_t k1)

 {
     c->k0 = k0;
     c->k1 = k1;
     c->sum0 = shift_16[k0];
     c->sum1 = shift_16[k1];
 }
 
 static int tta_get_unary(GetBitContext *gb)
 {
     int ret = 0;
 
     // count ones
     while(get_bits1(gb))
         ret++;
     return ret;
 }
 

 static av_cold int tta_decode_init(AVCodecContext * avctx)

 {
     TTAContext *s = avctx->priv_data;
     int i;
 
     s->avctx = avctx;
 
     // 30bytes includes a seektable with one frame
     if (avctx->extradata_size < 30)
         return -1;
 
     init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size);

     if (show_bits_long(&s->gb, 32) == AV_RL32("TTA1"))

     {
         /* signature */
         skip_bits(&s->gb, 32);

 //        if (get_bits_long(&s->gb, 32) != bswap_32(AV_RL32("TTA1"))) {

 //            av_log(s->avctx, AV_LOG_ERROR, "Missing magic\n");
 //            return -1;
 //        }
 

         s->flags = get_bits(&s->gb, 16);

         if (s->flags != 1 && s->flags != 3)
         {
             av_log(s->avctx, AV_LOG_ERROR, "Invalid flags\n");
             return -1;
         }
         s->is_float = (s->flags == FORMAT_FLOAT);

         avctx->channels = s->channels = get_bits(&s->gb, 16);

         avctx->bits_per_coded_sample = get_bits(&s->gb, 16);
         s->bps = (avctx->bits_per_coded_sample + 7) / 8;

         avctx->sample_rate = get_bits_long(&s->gb, 32);

         if(avctx->sample_rate > 1000000){ //prevent FRAME_TIME * avctx->sample_rate from overflowing and sanity check
             av_log(avctx, AV_LOG_ERROR, "sample_rate too large\n");
             return -1;
         }

         s->data_length = get_bits_long(&s->gb, 32);

         skip_bits(&s->gb, 32); // CRC32 of header
 
         if (s->is_float)
         {
             avctx->sample_fmt = SAMPLE_FMT_FLT;
             av_log(s->avctx, AV_LOG_ERROR, "Unsupported sample format. Please contact the developers.\n");
             return -1;
         }
         else switch(s->bps) {
 //            case 1: avctx->sample_fmt = SAMPLE_FMT_U8; break;
             case 2: avctx->sample_fmt = SAMPLE_FMT_S16; break;
 //            case 3: avctx->sample_fmt = SAMPLE_FMT_S24; break;
             case 4: avctx->sample_fmt = SAMPLE_FMT_S32; break;
             default:
                 av_log(s->avctx, AV_LOG_ERROR, "Invalid/unsupported sample format. Please contact the developers.\n");
                 return -1;
         }
 
         // FIXME: horribly broken, but directly from reference source
 #define FRAME_TIME 1.04489795918367346939
         s->frame_length = (int)(FRAME_TIME * avctx->sample_rate);
 
         s->last_frame_length = s->data_length % s->frame_length;
         s->total_frames = s->data_length / s->frame_length +
                         (s->last_frame_length ? 1 : 0);
 
         av_log(s->avctx, AV_LOG_DEBUG, "flags: %x chans: %d bps: %d rate: %d block: %d\n",

             s->flags, avctx->channels, avctx->bits_per_coded_sample, avctx->sample_rate,

             avctx->block_align);
         av_log(s->avctx, AV_LOG_DEBUG, "data_length: %d frame_length: %d last: %d total: %d\n",
             s->data_length, s->frame_length, s->last_frame_length, s->total_frames);
 
         // FIXME: seek table
         for (i = 0; i < s->total_frames; i++)
             skip_bits(&s->gb, 32);
         skip_bits(&s->gb, 32); // CRC32 of seektable
 

         if(s->frame_length >= UINT_MAX / (s->channels * sizeof(int32_t))){
             av_log(avctx, AV_LOG_ERROR, "frame_length too large\n");
             return -1;
         }
 

         s->decode_buffer = av_mallocz(sizeof(int32_t)*s->frame_length*s->channels);

     } else {
         av_log(avctx, AV_LOG_ERROR, "Wrong extradata present\n");
         return -1;
     }
 
     return 0;
 }
 
 static int tta_decode_frame(AVCodecContext *avctx,
         void *data, int *data_size,

         const uint8_t *buf, int buf_size)

 {
     TTAContext *s = avctx->priv_data;
     int i;
 
     init_get_bits(&s->gb, buf, buf_size*8);
     {

         int32_t predictors[s->channels];

         TTAFilter filters[s->channels];
         TTARice rices[s->channels];
         int cur_chan = 0, framelen = s->frame_length;

         int32_t *p;

 
         // FIXME: seeking
         s->total_frames--;
         if (!s->total_frames && s->last_frame_length)
             framelen = s->last_frame_length;
 
         // init per channel states
         for (i = 0; i < s->channels; i++) {
             predictors[i] = 0;
             ttafilter_init(&(filters[i]), ttafilter_configs[s->bps-1][0], ttafilter_configs[s->bps-1][1]);
             rice_init(&(rices[i]), 10, 10);
         }
 
         for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {

             int32_t *predictor = &(predictors[cur_chan]);

             TTAFilter *filter = &(filters[cur_chan]);
             TTARice *rice = &(rices[cur_chan]);

             uint32_t unary, depth, k;
             int32_t value;

 
             unary = tta_get_unary(&s->gb);
 
             if (unary == 0) {
                 depth = 0;
                 k = rice->k0;
             } else {
                 depth = 1;
                 k = rice->k1;
                 unary--;
             }
 
             if (k)
                 value = (unary << k) + get_bits(&s->gb, k);
             else
                 value = unary;
 
             // FIXME: copy paste from original
             switch (depth) {
             case 1:
                 rice->sum1 += value - (rice->sum1 >> 4);
                 if (rice->k1 > 0 && rice->sum1 < shift_16[rice->k1])
                     rice->k1--;
                 else if(rice->sum1 > shift_16[rice->k1 + 1])
                     rice->k1++;
                 value += shift_1[rice->k0];
             default:
                 rice->sum0 += value - (rice->sum0 >> 4);
                 if (rice->k0 > 0 && rice->sum0 < shift_16[rice->k0])
                     rice->k0--;
                 else if(rice->sum0 > shift_16[rice->k0 + 1])
                     rice->k0++;
             }
 

             // extract coded value
 #define UNFOLD(x) (((x)&1) ? (++(x)>>1) : (-(x)>>1))
             *p = UNFOLD(value);

 
             // run hybrid filter
             ttafilter_process(filter, p, 0);
 
             // fixed order prediction

 #define PRED(x, k) (int32_t)((((uint64_t)x << k) - x) >> k)

             switch (s->bps) {
                 case 1: *p += PRED(*predictor, 4); break;
                 case 2:
                 case 3: *p += PRED(*predictor, 5); break;
                 case 4: *p += *predictor; break;
             }
             *predictor = *p;
 
 #if 0
             // extract 32bit float from last two int samples
             if (s->is_float && ((p - data) & 1)) {

                 uint32_t neg = *p & 0x80000000;
                 uint32_t hi = *(p - 1);
                 uint32_t lo = abs(*p) - 1;

 
                 hi += (hi || lo) ? 0x3f80 : 0;
                 // SWAP16: swap all the 16 bits
                 *(p - 1) = (hi << 16) | SWAP16(lo) | neg;
             }
 #endif
 
             /*if ((get_bits_count(&s->gb)+7)/8 > buf_size)
             {
                 av_log(NULL, AV_LOG_INFO, "overread!!\n");
                 break;
             }*/
 
             // flip channels
             if (cur_chan < (s->channels-1))
                 cur_chan++;
             else {
                 // decorrelate in case of stereo integer
                 if (!s->is_float && (s->channels > 1)) {

                     int32_t *r = p - 1;

                     for (*p += *r / 2; r > p - s->channels; r--)
                         *r = *(r + 1) - *r;
                 }
                 cur_chan = 0;
             }
         }
 
         skip_bits(&s->gb, 32); // frame crc
 
         // convert to output buffer
         switch(s->bps) {
             case 2: {
                 uint16_t *samples = data;
                 for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {
 //                    *samples++ = (unsigned char)*p;
 //                    *samples++ = (unsigned char)(*p >> 8);
                     *samples++ = *p;
                 }
                 *data_size = (uint8_t *)samples - (uint8_t *)data;
                 break;
             }
             default:
                 av_log(s->avctx, AV_LOG_ERROR, "Error, only 16bit samples supported!\n");
         }
     }
 
 //    return get_bits_count(&s->gb)+7)/8;
     return buf_size;
 }
 

 static av_cold int tta_decode_close(AVCodecContext *avctx) {

     TTAContext *s = avctx->priv_data;
 
     if (s->decode_buffer)
         av_free(s->decode_buffer);
 
     return 0;
 }
 
 AVCodec tta_decoder = {
     "tta",
     CODEC_TYPE_AUDIO,
     CODEC_ID_TTA,
     sizeof(TTAContext),
     tta_decode_init,
     NULL,
     tta_decode_close,
     tta_decode_frame,

     .long_name = NULL_IF_CONFIG_SMALL("True Audio (TTA)"),

 };