/*
  * Lagarith lossless decoder
  * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
  *
  * 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

  * Lagarith lossless decoder
  * @author Nathan Caldwell
  */
 
 #include "avcodec.h"
 #include "get_bits.h"
 #include "mathops.h"
 #include "dsputil.h"
 #include "lagarithrac.h"

 #include "thread.h"

 
 enum LagarithFrameType {

     FRAME_RAW           = 1,    /**< uncompressed */
     FRAME_U_RGB24       = 2,    /**< unaligned RGB24 */
     FRAME_ARITH_YUY2    = 3,    /**< arithmetic coded YUY2 */
     FRAME_ARITH_RGB24   = 4,    /**< arithmetic coded RGB24 */
     FRAME_SOLID_GRAY    = 5,    /**< solid grayscale color frame */
     FRAME_SOLID_COLOR   = 6,    /**< solid non-grayscale color frame */
     FRAME_OLD_ARITH_RGB = 7,    /**< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
     FRAME_ARITH_RGBA    = 8,    /**< arithmetic coded RGBA */
     FRAME_SOLID_RGBA    = 9,    /**< solid RGBA color frame */
     FRAME_ARITH_YV12    = 10,   /**< arithmetic coded YV12 */
     FRAME_REDUCED_RES   = 11,   /**< reduced resolution YV12 frame */

 };
 
 typedef struct LagarithContext {
     AVCodecContext *avctx;
     AVFrame picture;
     DSPContext dsp;

     int zeros;                  /**< number of consecutive zero bytes encountered */
     int zeros_rem;              /**< number of zero bytes remaining to output */

     uint8_t *rgb_planes;

     int      rgb_planes_allocated;

     int rgb_stride;

 } LagarithContext;
 
 /**
  * Compute the 52bit mantissa of 1/(double)denom.
  * This crazy format uses floats in an entropy coder and we have to match x86
  * rounding exactly, thus ordinary floats aren't portable enough.
  * @param denom denominator
  * @return 52bit mantissa
  * @see softfloat_mul
  */
 static uint64_t softfloat_reciprocal(uint32_t denom)
 {
     int shift = av_log2(denom - 1) + 1;
     uint64_t ret = (1ULL << 52) / denom;
     uint64_t err = (1ULL << 52) - ret * denom;
     ret <<= shift;
     err <<= shift;
     err +=  denom / 2;
     return ret + err / denom;
 }
 
 /**
  * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
  * Used in combination with softfloat_reciprocal computes x/(double)denom.
  * @param x 32bit integer factor
  * @param mantissa mantissa of f with exponent 0
  * @return 32bit integer value (x*f)
  * @see softfloat_reciprocal
  */
 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
 {
     uint64_t l = x * (mantissa & 0xffffffff);
     uint64_t h = x * (mantissa >> 32);
     h += l >> 32;
     l &= 0xffffffff;
     l += 1 << av_log2(h >> 21);
     h += l >> 32;
     return h >> 20;
 }
 
 static uint8_t lag_calc_zero_run(int8_t x)
 {
     return (x << 1) ^ (x >> 7);
 }
 
 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
 {
     static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
     int i;
     int bit     = 0;
     int bits    = 0;
     int prevbit = 0;
     unsigned val;
 
     for (i = 0; i < 7; i++) {
         if (prevbit && bit)
             break;
         prevbit = bit;
         bit = get_bits1(gb);
         if (bit && !prevbit)
             bits += series[i];
     }
     bits--;
     if (bits < 0 || bits > 31) {
         *value = 0;
         return -1;
     } else if (bits == 0) {
         *value = 0;
         return 0;
     }
 
     val  = get_bits_long(gb, bits);
     val |= 1 << bits;
 
     *value = val - 1;
 
     return 0;
 }
 
 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
 {
     int i, j, scale_factor;
     unsigned prob, cumulative_target;
     unsigned cumul_prob = 0;
     unsigned scaled_cumul_prob = 0;
 
     rac->prob[0] = 0;
     rac->prob[257] = UINT_MAX;
     /* Read probabilities from bitstream */
     for (i = 1; i < 257; i++) {
         if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
             av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
             return -1;
         }
         if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
             av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
             return -1;
         }
         cumul_prob += rac->prob[i];
         if (!rac->prob[i]) {
             if (lag_decode_prob(gb, &prob)) {
                 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
                 return -1;
             }

             if (prob > 256 - i)
                 prob = 256 - i;

             for (j = 0; j < prob; j++)
                 rac->prob[++i] = 0;
         }
     }
 
     if (!cumul_prob) {
         av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
         return -1;
     }
 
     /* Scale probabilities so cumulative probability is an even power of 2. */
     scale_factor = av_log2(cumul_prob);
 
     if (cumul_prob & (cumul_prob - 1)) {
         uint64_t mul = softfloat_reciprocal(cumul_prob);
         for (i = 1; i < 257; i++) {
             rac->prob[i] = softfloat_mul(rac->prob[i], mul);
             scaled_cumul_prob += rac->prob[i];
         }
 
         scale_factor++;
         cumulative_target = 1 << scale_factor;
 
         if (scaled_cumul_prob > cumulative_target) {
             av_log(rac->avctx, AV_LOG_ERROR,
                    "Scaled probabilities are larger than target!\n");
             return -1;
         }
 
         scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
 
         for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
             if (rac->prob[i]) {
                 rac->prob[i]++;
                 scaled_cumul_prob--;
             }
             /* Comment from reference source:
              * if (b & 0x80 == 0) {     // order of operations is 'wrong'; it has been left this way

              *                          // since the compression change is negligible and fixing it

              *                          // breaks backwards compatibility

              *      b =- (signed int)b;
              *      b &= 0xFF;
              * } else {
              *      b++;
              *      b &= 0x7f;
              * }
              */
         }
     }
 
     rac->scale = scale_factor;
 
     /* Fill probability array with cumulative probability for each symbol. */
     for (i = 1; i < 257; i++)
         rac->prob[i] += rac->prob[i - 1];
 
     return 0;
 }
 
 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
                                       uint8_t *diff, int w, int *left,
                                       int *left_top)
 {
     /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
      * However the &0xFF on the gradient predictor yealds incorrect output
      * for lagarith.
      */
     int i;
     uint8_t l, lt;
 
     l  = *left;
     lt = *left_top;
 
     for (i = 0; i < w; i++) {
         l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
         lt = src1[i];
         dst[i] = l;
     }
 
     *left     = l;
     *left_top = lt;
 }
 
 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
                           int width, int stride, int line)
 {
     int L, TL;
 
     if (!line) {
         /* Left prediction only for first line */

         L = l->dsp.add_hfyu_left_prediction(buf, buf,
                                             width, 0);

     } else {

         /* Left pixel is actually prev_row[width] */
         L = buf[width - stride - 1];
 
         if (line == 1) {
             /* Second line, left predict first pixel, the rest of the line is median predicted
              * NOTE: In the case of RGB this pixel is top predicted */

             TL = l->avctx->pix_fmt == AV_PIX_FMT_YUV420P ? buf[-stride] : L;

         } else {
             /* Top left is 2 rows back, last pixel */
             TL = buf[width - (2 * stride) - 1];
         }

         add_lag_median_prediction(buf, buf - stride, buf,
                                   width, &L, &TL);
     }

 }
 

 static void lag_pred_line_yuy2(LagarithContext *l, uint8_t *buf,
                                int width, int stride, int line,
                                int is_luma)
 {
     int L, TL;
 
     if (!line) {

         L= buf[0];
         if (is_luma)
             buf[0] = 0;
         l->dsp.add_hfyu_left_prediction(buf, buf, width, 0);
         if (is_luma)
             buf[0] = L;

         return;
     }
     if (line == 1) {
         const int HEAD = is_luma ? 4 : 2;
         int i;
 
         L  = buf[width - stride - 1];
         TL = buf[HEAD  - stride - 1];
         for (i = 0; i < HEAD; i++) {
             L += buf[i];
             buf[i] = L;
         }

         for (; i<width; i++) {
             L     = mid_pred(L&0xFF, buf[i-stride], (L + buf[i-stride] - TL)&0xFF) + buf[i];
             TL    = buf[i-stride];
             buf[i]= L;
         }

     } else {
         TL = buf[width - (2 * stride) - 1];
         L  = buf[width - stride - 1];

         l->dsp.add_hfyu_median_prediction(buf, buf - stride, buf, width,
                                         &L, &TL);

     }
 }
 

 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
                            uint8_t *dst, int width, int stride,
                            int esc_count)
 {
     int i = 0;
     int ret = 0;
 
     if (!esc_count)
         esc_count = -1;
 
     /* Output any zeros remaining from the previous run */
 handle_zeros:
     if (l->zeros_rem) {
         int count = FFMIN(l->zeros_rem, width - i);
         memset(dst + i, 0, count);
         i += count;
         l->zeros_rem -= count;
     }
 
     while (i < width) {
         dst[i] = lag_get_rac(rac);
         ret++;
 
         if (dst[i])
             l->zeros = 0;
         else
             l->zeros++;
 
         i++;
         if (l->zeros == esc_count) {
             int index = lag_get_rac(rac);
             ret++;
 
             l->zeros = 0;
 
             l->zeros_rem = lag_calc_zero_run(index);
             goto handle_zeros;
         }
     }
     return ret;
 }
 
 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,

                                     const uint8_t *src, const uint8_t *src_end,
                                     int width, int esc_count)

 {
     int i = 0;
     int count;
     uint8_t zero_run = 0;

     const uint8_t *src_start = src;

     uint8_t mask1 = -(esc_count < 2);
     uint8_t mask2 = -(esc_count < 3);
     uint8_t *end = dst + (width - 2);
 
 output_zeros:
     if (l->zeros_rem) {
         count = FFMIN(l->zeros_rem, width - i);

         if (end - dst < count) {
             av_log(l->avctx, AV_LOG_ERROR, "Too many zeros remaining.\n");

             return AVERROR_INVALIDDATA;
         }

         memset(dst, 0, count);
         l->zeros_rem -= count;
         dst += count;
     }
 
     while (dst < end) {
         i = 0;
         while (!zero_run && dst + i < end) {
             i++;

             if (i+2 >= src_end - src)

                 return AVERROR_INVALIDDATA;

             zero_run =
                 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
         }
         if (zero_run) {
             zero_run = 0;
             i += esc_count;
             memcpy(dst, src, i);
             dst += i;
             l->zeros_rem = lag_calc_zero_run(src[i]);
 
             src += i + 1;
             goto output_zeros;
         } else {
             memcpy(dst, src, i);
             src += i;

             dst += i;

         }
     }

     return  src - src_start;

 }
 
 
 
 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
                                   int width, int height, int stride,
                                   const uint8_t *src, int src_size)
 {
     int i = 0;
     int read = 0;
     uint32_t length;
     uint32_t offset = 1;

     int esc_count;

     GetBitContext gb;
     lag_rac rac;

     const uint8_t *src_end = src + src_size;

 
     rac.avctx = l->avctx;
     l->zeros = 0;
 

     if(src_size < 2)
         return AVERROR_INVALIDDATA;
 
     esc_count = src[0];

     if (esc_count < 4) {
         length = width * height;

         if(src_size < 5)
             return AVERROR_INVALIDDATA;

         if (esc_count && AV_RL32(src + 1) < length) {
             length = AV_RL32(src + 1);
             offset += 4;
         }
 
         init_get_bits(&gb, src + offset, src_size * 8);
 
         if (lag_read_prob_header(&rac, &gb) < 0)
             return -1;
 

         ff_lag_rac_init(&rac, &gb, length - stride);

 
         for (i = 0; i < height; i++)
             read += lag_decode_line(l, &rac, dst + (i * stride), width,
                                     stride, esc_count);
 
         if (read > length)
             av_log(l->avctx, AV_LOG_WARNING,
                    "Output more bytes than length (%d of %d)\n", read,
                    length);
     } else if (esc_count < 8) {
         esc_count -= 4;
         if (esc_count > 0) {
             /* Zero run coding only, no range coding. */

             for (i = 0; i < height; i++) {
                 int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
                                                    src_end, width, esc_count);
                 if (res < 0)
                     return res;
                 src += res;
             }

         } else {

             if (src_size < width * height)
                 return AVERROR_INVALIDDATA; // buffer not big enough

             /* Plane is stored uncompressed */
             for (i = 0; i < height; i++) {
                 memcpy(dst + (i * stride), src, width);
                 src += width;
             }
         }
     } else if (esc_count == 0xff) {

         /* Plane is a solid run of given value */

         for (i = 0; i < height; i++)

             memset(dst + i * stride, src[1], width);
         /* Do not apply prediction.
            Note: memset to 0 above, setting first value to src[1]
            and applying prediction gives the same result. */
         return 0;

     } else {
         av_log(l->avctx, AV_LOG_ERROR,
                "Invalid zero run escape code! (%#x)\n", esc_count);
         return -1;
     }
 

     if (l->avctx->pix_fmt != AV_PIX_FMT_YUV422P) {

         for (i = 0; i < height; i++) {
             lag_pred_line(l, dst, width, stride, i);
             dst += stride;
         }
     } else {
         for (i = 0; i < height; i++) {
             lag_pred_line_yuy2(l, dst, width, stride, i,
                                width == l->avctx->width);
             dst += stride;
         }

     }
 
     return 0;
 }
 
 /**
  * Decode a frame.
  * @param avctx codec context
  * @param data output AVFrame
  * @param data_size size of output data or 0 if no picture is returned
  * @param avpkt input packet
  * @return number of consumed bytes on success or negative if decode fails
  */
 static int lag_decode_frame(AVCodecContext *avctx,

                             void *data, int *got_frame, AVPacket *avpkt)

 {
     const uint8_t *buf = avpkt->data;

     unsigned int buf_size = avpkt->size;

     LagarithContext *l = avctx->priv_data;
     AVFrame *const p = &l->picture;
     uint8_t frametype = 0;
     uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;

     uint32_t offs[4];

     uint8_t *srcs[4], *dst;

     int i, j, planes = 3;

 
     AVFrame *picture = data;
 
     if (p->data[0])

         ff_thread_release_buffer(avctx, p);

 
     p->reference = 0;
     p->key_frame = 1;
 
     frametype = buf[0];
 
     offset_gu = AV_RL32(buf + 1);
     offset_bv = AV_RL32(buf + 5);
 
     switch (frametype) {

     case FRAME_SOLID_RGBA:

         avctx->pix_fmt = AV_PIX_FMT_RGB32;

         if (ff_thread_get_buffer(avctx, p) < 0) {

             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }
 
         dst = p->data[0];
         for (j = 0; j < avctx->height; j++) {
             for (i = 0; i < avctx->width; i++)
                 AV_WN32(dst + i * 4, offset_gu);
             dst += p->linesize[0];
         }
         break;
     case FRAME_ARITH_RGBA:

         avctx->pix_fmt = AV_PIX_FMT_RGB32;

         planes = 4;
         offset_ry += 4;
         offs[3] = AV_RL32(buf + 9);
     case FRAME_ARITH_RGB24:

     case FRAME_U_RGB24:
         if (frametype == FRAME_ARITH_RGB24 || frametype == FRAME_U_RGB24)

             avctx->pix_fmt = AV_PIX_FMT_RGB24;

         if (ff_thread_get_buffer(avctx, p) < 0) {

             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }

         offs[0] = offset_bv;
         offs[1] = offset_gu;

         offs[2] = offset_ry;

         l->rgb_stride = FFALIGN(avctx->width, 16);
         av_fast_malloc(&l->rgb_planes, &l->rgb_planes_allocated,
                        l->rgb_stride * avctx->height * planes + 1);

         if (!l->rgb_planes) {

             av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
             return AVERROR(ENOMEM);

         }

         for (i = 0; i < planes; i++)

             srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;

         for (i = 0; i < planes; i++)

             if (buf_size <= offs[i]) {

                 av_log(avctx, AV_LOG_ERROR,
                         "Invalid frame offsets\n");

                 return AVERROR_INVALIDDATA;
             }

         for (i = 0; i < planes; i++)

             lag_decode_arith_plane(l, srcs[i],
                                    avctx->width, avctx->height,
                                    -l->rgb_stride, buf + offs[i],

                                    buf_size - offs[i]);

         dst = p->data[0];

         for (i = 0; i < planes; i++)

             srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
         for (j = 0; j < avctx->height; j++) {
             for (i = 0; i < avctx->width; i++) {
                 uint8_t r, g, b, a;
                 r = srcs[0][i];
                 g = srcs[1][i];
                 b = srcs[2][i];
                 r += g;
                 b += g;

                 if (frametype == FRAME_ARITH_RGBA) {
                     a = srcs[3][i];
                     AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
                 } else {
                     dst[i * 3 + 0] = r;
                     dst[i * 3 + 1] = g;
                     dst[i * 3 + 2] = b;
                 }

             }
             dst += p->linesize[0];

             for (i = 0; i < planes; i++)

                 srcs[i] += l->rgb_stride;
         }
         break;

     case FRAME_ARITH_YUY2:

         avctx->pix_fmt = AV_PIX_FMT_YUV422P;

         if (ff_thread_get_buffer(avctx, p) < 0) {

             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }
 
         if (offset_ry >= buf_size ||
             offset_gu >= buf_size ||
             offset_bv >= buf_size) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid frame offsets\n");
             return AVERROR_INVALIDDATA;
         }
 
         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
                                p->linesize[0], buf + offset_ry,
                                buf_size - offset_ry);
         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
                                avctx->height, p->linesize[1],

                                buf + offset_gu, buf_size - offset_gu);
         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
                                avctx->height, p->linesize[2],

                                buf + offset_bv, buf_size - offset_bv);
         break;

     case FRAME_ARITH_YV12:

         avctx->pix_fmt = AV_PIX_FMT_YUV420P;

         if (ff_thread_get_buffer(avctx, p) < 0) {

             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }

         if (buf_size <= offset_ry || buf_size <= offset_gu || buf_size <= offset_bv) {
             return AVERROR_INVALIDDATA;
         }

         if (offset_ry >= buf_size ||
             offset_gu >= buf_size ||
             offset_bv >= buf_size) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid frame offsets\n");
             return AVERROR_INVALIDDATA;
         }
 

         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
                                p->linesize[0], buf + offset_ry,

                                buf_size - offset_ry);

         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
                                avctx->height / 2, p->linesize[2],

                                buf + offset_gu, buf_size - offset_gu);

         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
                                avctx->height / 2, p->linesize[1],

                                buf + offset_bv, buf_size - offset_bv);

         break;
     default:
         av_log(avctx, AV_LOG_ERROR,
                "Unsupported Lagarith frame type: %#x\n", frametype);
         return -1;
     }
 
     *picture = *p;

     *got_frame = 1;

 
     return buf_size;
 }
 
 static av_cold int lag_decode_init(AVCodecContext *avctx)
 {
     LagarithContext *l = avctx->priv_data;
     l->avctx = avctx;
 

     ff_dsputil_init(&l->dsp, avctx);

 
     return 0;
 }
 
 static av_cold int lag_decode_end(AVCodecContext *avctx)
 {
     LagarithContext *l = avctx->priv_data;
 
     if (l->picture.data[0])

         ff_thread_release_buffer(avctx, &l->picture);

     av_freep(&l->rgb_planes);

 
     return 0;
 }
 

 AVCodec ff_lagarith_decoder = {

     .name           = "lagarith",
     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_LAGARITH,

     .priv_data_size = sizeof(LagarithContext),
     .init           = lag_decode_init,
     .close          = lag_decode_end,
     .decode         = lag_decode_frame,

     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,

     .long_name      = NULL_IF_CONFIG_SMALL("Lagarith lossless"),

 };