/*
  * OpenEXR (.exr) image decoder
  * Copyright (c) 2009 Jimmy Christensen
  *
  * 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

  * OpenEXR decoder
  * @author Jimmy Christensen
  *
  * For more information on the OpenEXR format, visit:
  *  http://openexr.com/
  *

  * exr_flt2uint() and exr_halflt2uint() is credited to Reimar Döffinger.
  * exr_half2float() is credited to Aaftab Munshi, Dan Ginsburg, Dave Shreiner.

  */
 

 #include <float.h>

 #include <zlib.h>

 #include "libavutil/imgutils.h"

 #include "libavutil/intfloat.h"

 #include "libavutil/opt.h"
 

 #include "avcodec.h"
 #include "bytestream.h"

 #include "get_bits.h"

 #include "internal.h"

 #include "mathops.h"

 #include "thread.h"

 
 enum ExrCompr {

     EXR_RAW,
     EXR_RLE,
     EXR_ZIP1,
     EXR_ZIP16,
     EXR_PIZ,
     EXR_PXR24,
     EXR_B44,
     EXR_B44A,
     EXR_UNKN,

 };
 

 enum ExrPixelType {
     EXR_UINT,
     EXR_HALF,

     EXR_FLOAT,
     EXR_UNKNOWN,

 };
 
 typedef struct EXRChannel {

     int xsub, ysub;

     enum ExrPixelType pixel_type;
 } EXRChannel;
 

 typedef struct EXRThreadData {
     uint8_t *uncompressed_data;
     int uncompressed_size;
 
     uint8_t *tmp;
     int tmp_size;

 
     uint8_t *bitmap;
     uint16_t *lut;

 } EXRThreadData;
 

 typedef struct EXRContext {

     AVClass *class;

     AVFrame *picture;

     AVCodecContext *avctx;
 
     enum ExrCompr compression;

     enum ExrPixelType pixel_type;

     int channel_offsets[4]; // 0 = red, 1 = green, 2 = blue and 3 = alpha

     const AVPixFmtDescriptor *desc;

     int w, h;

     uint32_t xmax, xmin;
     uint32_t ymax, ymin;
     uint32_t xdelta, ydelta;

     int ysize;
 

     uint64_t scan_line_size;
     int scan_lines_per_block;
 

     GetByteContext gb;
     const uint8_t *buf;

     int buf_size;
 

     EXRChannel *channels;
     int nb_channels;
 

     EXRThreadData *thread_data;

     const char *layer;

 
     float gamma;
     uint16_t gamma_table[65536];

 } EXRContext;
 

 /* -15 stored using a single precision bias of 127 */
 #define HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP 0x38000000

 /* max exponent value in single precision that will be converted
  * to Inf or Nan when stored as a half-float */
 #define HALF_FLOAT_MAX_BIASED_EXP_AS_SINGLE_FP_EXP 0x47800000
 
 /* 255 is the max exponent biased value */
 #define FLOAT_MAX_BIASED_EXP (0xFF << 23)
 
 #define HALF_FLOAT_MAX_BIASED_EXP (0x1F << 10)
 

 /**

  * Convert a half float as a uint16_t into a full float.
  *
  * @param hf half float as uint16_t
  *
  * @return float value
  */
 static union av_intfloat32 exr_half2float(uint16_t hf)
 {

     unsigned int sign = (unsigned int) (hf >> 15);
     unsigned int mantissa = (unsigned int) (hf & ((1 << 10) - 1));
     unsigned int exp = (unsigned int) (hf & HALF_FLOAT_MAX_BIASED_EXP);
     union av_intfloat32 f;

 
     if (exp == HALF_FLOAT_MAX_BIASED_EXP) {
         // we have a half-float NaN or Inf
         // half-float NaNs will be converted to a single precision NaN
         // half-float Infs will be converted to a single precision Inf
         exp = FLOAT_MAX_BIASED_EXP;
         if (mantissa)
             mantissa = (1 << 23) - 1;    // set all bits to indicate a NaN
     } else if (exp == 0x0) {
         // convert half-float zero/denorm to single precision value
         if (mantissa) {
             mantissa <<= 1;
             exp = HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP;
             // check for leading 1 in denorm mantissa
             while ((mantissa & (1 << 10))) {
                 // for every leading 0, decrement single precision exponent by 1
                 // and shift half-float mantissa value to the left
                 mantissa <<= 1;
                 exp -= (1 << 23);
             }
             // clamp the mantissa to 10-bits
             mantissa &= ((1 << 10) - 1);
             // shift left to generate single-precision mantissa of 23-bits
             mantissa <<= 13;
         }
     } else {
         // shift left to generate single-precision mantissa of 23-bits
         mantissa <<= 13;
         // generate single precision biased exponent value
         exp = (exp << 13) + HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP;
     }
 
     f.i = (sign << 31) | exp | mantissa;
 
     return f;
 }
 
 

 /**

  * Convert from 32-bit float as uint32_t to uint16_t.

  *
  * @param v 32-bit float

  *

  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_flt2uint(uint32_t v)
 {
     unsigned int exp = v >> 23;
     // "HACK": negative values result in exp<  0, so clipping them to 0
     // is also handled by this condition, avoids explicit check for sign bit.

     if (exp <= 127 + 7 - 24) // we would shift out all bits anyway

         return 0;
     if (exp >= 127)
         return 0xffff;
     v &= 0x007fffff;
     return (v + (1 << 23)) >> (127 + 7 - exp);
 }
 
 /**

  * Convert from 16-bit float as uint16_t to uint16_t.

  *
  * @param v 16-bit float

  *

  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_halflt2uint(uint16_t v)
 {

     unsigned exp = 14 - (v >> 10);
     if (exp >= 14) {

         if (exp == 14)
             return (v >> 9) & 1;
         else
             return (v & 0x8000) ? 0 : 0xffff;

     }

     v <<= 6;

     return (v + (1 << 16)) >> (exp + 1);

 }
 

 static void predictor(uint8_t *src, int size)
 {

     uint8_t *t    = src + 1;

     uint8_t *stop = src + size;
 
     while (t < stop) {

         int d = (int) t[-1] + (int) t[0] - 128;

         t[0] = d;
         ++t;
     }
 }
 
 static void reorder_pixels(uint8_t *src, uint8_t *dst, int size)
 {
     const int8_t *t1 = src;
     const int8_t *t2 = src + (size + 1) / 2;

     int8_t *s        = dst;
     int8_t *stop     = s + size;

 
     while (1) {
         if (s < stop)
             *(s++) = *(t1++);
         else
             break;
 
         if (s < stop)
             *(s++) = *(t2++);
         else
             break;
     }
 }
 

 static int zip_uncompress(const uint8_t *src, int compressed_size,
                           int uncompressed_size, EXRThreadData *td)

 {

     unsigned long dest_len = uncompressed_size;
 
     if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
         dest_len != uncompressed_size)

         return AVERROR_INVALIDDATA;

 
     predictor(td->tmp, uncompressed_size);
     reorder_pixels(td->tmp, td->uncompressed_data, uncompressed_size);
 
     return 0;
 }
 
 static int rle_uncompress(const uint8_t *src, int compressed_size,
                           int uncompressed_size, EXRThreadData *td)
 {

     uint8_t *d      = td->tmp;
     const int8_t *s = src;
     int ssize       = compressed_size;
     int dsize       = uncompressed_size;
     uint8_t *dend   = d + dsize;

     int count;
 
     while (ssize > 0) {
         count = *s++;
 
         if (count < 0) {
             count = -count;
 

             if ((dsize -= count) < 0 ||

                 (ssize -= count + 1) < 0)

                 return AVERROR_INVALIDDATA;

 
             while (count--)
                 *d++ = *s++;
         } else {
             count++;
 
             if ((dsize -= count) < 0 ||

                 (ssize -= 2) < 0)
                 return AVERROR_INVALIDDATA;

 
             while (count--)
                 *d++ = *s;
 
             s++;
         }
     }
 

     if (dend != d)
         return AVERROR_INVALIDDATA;
 
     predictor(td->tmp, uncompressed_size);
     reorder_pixels(td->tmp, td->uncompressed_data, uncompressed_size);
 
     return 0;

 }
 

 #define USHORT_RANGE (1 << 16)

 #define BITMAP_SIZE  (1 << 13)

 
 static uint16_t reverse_lut(const uint8_t *bitmap, uint16_t *lut)
 {
     int i, k = 0;
 

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

         if ((i == 0) || (bitmap[i >> 3] & (1 << (i & 7))))
             lut[k++] = i;
 
     i = k - 1;
 

     memset(lut + k, 0, (USHORT_RANGE - k) * 2);

 
     return i;
 }
 
 static void apply_lut(const uint16_t *lut, uint16_t *dst, int dsize)
 {
     int i;
 
     for (i = 0; i < dsize; ++i)
         dst[i] = lut[dst[i]];
 }
 
 #define HUF_ENCBITS 16  // literal (value) bit length
 #define HUF_DECBITS 14  // decoding bit size (>= 8)
 
 #define HUF_ENCSIZE ((1 << HUF_ENCBITS) + 1)  // encoding table size

 #define HUF_DECSIZE (1 << HUF_DECBITS)        // decoding table size

 #define HUF_DECMASK (HUF_DECSIZE - 1)
 
 typedef struct HufDec {
     int len;
     int lit;
     int *p;
 } HufDec;
 
 static void huf_canonical_code_table(uint64_t *hcode)
 {
     uint64_t c, n[59] = { 0 };
     int i;
 
     for (i = 0; i < HUF_ENCSIZE; ++i)
         n[hcode[i]] += 1;
 
     c = 0;
     for (i = 58; i > 0; --i) {
         uint64_t nc = ((c + n[i]) >> 1);
         n[i] = c;

         c    = nc;

     }
 
     for (i = 0; i < HUF_ENCSIZE; ++i) {
         int l = hcode[i];
 
         if (l > 0)
             hcode[i] = l | (n[l]++ << 6);
     }
 }
 
 #define SHORT_ZEROCODE_RUN  59
 #define LONG_ZEROCODE_RUN   63
 #define SHORTEST_LONG_RUN   (2 + LONG_ZEROCODE_RUN - SHORT_ZEROCODE_RUN)
 #define LONGEST_LONG_RUN    (255 + SHORTEST_LONG_RUN)
 
 static int huf_unpack_enc_table(GetByteContext *gb,
                                 int32_t im, int32_t iM, uint64_t *hcode)
 {
     GetBitContext gbit;

     int ret = init_get_bits8(&gbit, gb->buffer, bytestream2_get_bytes_left(gb));
     if (ret < 0)
         return ret;

 
     for (; im <= iM; im++) {
         uint64_t l = hcode[im] = get_bits(&gbit, 6);
 
         if (l == LONG_ZEROCODE_RUN) {
             int zerun = get_bits(&gbit, 8) + SHORTEST_LONG_RUN;
 
             if (im + zerun > iM + 1)
                 return AVERROR_INVALIDDATA;
 
             while (zerun--)
                 hcode[im++] = 0;
 
             im--;

         } else if (l >= SHORT_ZEROCODE_RUN) {

             int zerun = l - SHORT_ZEROCODE_RUN + 2;
 
             if (im + zerun > iM + 1)
                 return AVERROR_INVALIDDATA;
 
             while (zerun--)
                 hcode[im++] = 0;
 
             im--;
         }
     }
 
     bytestream2_skip(gb, (get_bits_count(&gbit) + 7) / 8);
     huf_canonical_code_table(hcode);
 
     return 0;
 }
 
 static int huf_build_dec_table(const uint64_t *hcode, int im,
                                int iM, HufDec *hdecod)
 {
     for (; im <= iM; im++) {
         uint64_t c = hcode[im] >> 6;
         int i, l = hcode[im] & 63;
 
         if (c >> l)
             return AVERROR_INVALIDDATA;
 
         if (l > HUF_DECBITS) {
             HufDec *pl = hdecod + (c >> (l - HUF_DECBITS));
             if (pl->len)
                 return AVERROR_INVALIDDATA;
 
             pl->lit++;
 

             pl->p = av_realloc(pl->p, pl->lit * sizeof(int));

             if (!pl->p)
                 return AVERROR(ENOMEM);
 
             pl->p[pl->lit - 1] = im;
         } else if (l) {
             HufDec *pl = hdecod + (c << (HUF_DECBITS - l));
 
             for (i = 1 << (HUF_DECBITS - l); i > 0; i--, pl++) {
                 if (pl->len || pl->p)
                     return AVERROR_INVALIDDATA;
                 pl->len = l;
                 pl->lit = im;
             }
         }
     }
 
     return 0;
 }
 

 #define get_char(c, lc, gb)                                                   \
 {                                                                             \
         c   = (c << 8) | bytestream2_get_byte(gb);                            \
         lc += 8;                                                              \

 }
 

 #define get_code(po, rlc, c, lc, gb, out, oe, outb)                           \

 {                                                                             \
         if (po == rlc) {                                                      \
             if (lc < 8)                                                       \
                 get_char(c, lc, gb);                                          \
             lc -= 8;                                                          \
                                                                               \
             cs = c >> lc;                                                     \
                                                                               \

             if (out + cs > oe || out == outb)                                 \

                 return AVERROR_INVALIDDATA;                                   \
                                                                               \
             s = out[-1];                                                      \
                                                                               \
             while (cs-- > 0)                                                  \
                 *out++ = s;                                                   \
         } else if (out < oe) {                                                \
             *out++ = po;                                                      \
         } else {                                                              \
             return AVERROR_INVALIDDATA;                                       \
         }                                                                     \

 }
 
 static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
                       GetByteContext *gb, int nbits,
                       int rlc, int no, uint16_t *out)
 {

     uint64_t c        = 0;
     uint16_t *outb    = out;
     uint16_t *oe      = out + no;

     const uint8_t *ie = gb->buffer + (nbits + 7) / 8; // input byte size
     uint8_t cs, s;
     int i, lc = 0;
 
     while (gb->buffer < ie) {
         get_char(c, lc, gb);
 
         while (lc >= HUF_DECBITS) {

             const HufDec pl = hdecod[(c >> (lc - HUF_DECBITS)) & HUF_DECMASK];

 
             if (pl.len) {
                 lc -= pl.len;

                 get_code(pl.lit, rlc, c, lc, gb, out, oe, outb);

             } else {
                 int j;
 
                 if (!pl.p)
                     return AVERROR_INVALIDDATA;
 
                 for (j = 0; j < pl.lit; j++) {
                     int l = hcode[pl.p[j]] & 63;
 
                     while (lc < l && bytestream2_get_bytes_left(gb) > 0)
                         get_char(c, lc, gb);
 
                     if (lc >= l) {
                         if ((hcode[pl.p[j]] >> 6) ==
                             ((c >> (lc - l)) & ((1LL << l) - 1))) {
                             lc -= l;

                             get_code(pl.p[j], rlc, c, lc, gb, out, oe, outb);

                             break;
                         }
                     }
                 }
 
                 if (j == pl.lit)
                     return AVERROR_INVALIDDATA;
             }
         }
     }
 

     i   = (8 - nbits) & 7;

     c >>= i;
     lc -= i;
 
     while (lc > 0) {
         const HufDec pl = hdecod[(c << (HUF_DECBITS - lc)) & HUF_DECMASK];
 
         if (pl.len) {
             lc -= pl.len;

             get_code(pl.lit, rlc, c, lc, gb, out, oe, outb);

         } else {
             return AVERROR_INVALIDDATA;
         }
     }
 
     if (out - outb != no)
         return AVERROR_INVALIDDATA;
     return 0;
 }
 
 static int huf_uncompress(GetByteContext *gb,
                           uint16_t *dst, int dst_size)
 {
     int32_t src_size, im, iM;
     uint32_t nBits;
     uint64_t *freq;
     HufDec *hdec;
     int ret, i;
 
     src_size = bytestream2_get_le32(gb);

     im       = bytestream2_get_le32(gb);
     iM       = bytestream2_get_le32(gb);

     bytestream2_skip(gb, 4);
     nBits = bytestream2_get_le32(gb);
     if (im < 0 || im >= HUF_ENCSIZE ||
         iM < 0 || iM >= HUF_ENCSIZE ||
         src_size < 0)
         return AVERROR_INVALIDDATA;
 
     bytestream2_skip(gb, 4);
 

     freq = av_mallocz_array(HUF_ENCSIZE, sizeof(*freq));
     hdec = av_mallocz_array(HUF_DECSIZE, sizeof(*hdec));

     if (!freq || !hdec) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }
 
     if ((ret = huf_unpack_enc_table(gb, im, iM, freq)) < 0)
         goto fail;
 
     if (nBits > 8 * bytestream2_get_bytes_left(gb)) {
         ret = AVERROR_INVALIDDATA;
         goto fail;
     }
 
     if ((ret = huf_build_dec_table(freq, im, iM, hdec)) < 0)
         goto fail;
     ret = huf_decode(freq, hdec, gb, nBits, iM, dst_size, dst);
 
 fail:

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

         if (hdec)

             av_freep(&hdec[i].p);

 
     av_free(freq);
     av_free(hdec);
 
     return ret;
 }
 
 static inline void wdec14(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
 {
     int16_t ls = l;
     int16_t hs = h;

     int hi     = hs;
     int ai     = ls + (hi & 1) + (hi >> 1);

     int16_t as = ai;
     int16_t bs = ai - hi;
 
     *a = as;
     *b = bs;
 }
 
 #define NBITS      16

 #define A_OFFSET  (1 << (NBITS - 1))

 #define MOD_MASK  ((1 << NBITS) - 1)
 
 static inline void wdec16(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
 {

     int m  = l;
     int d  = h;

     int bb = (m - (d >> 1)) & MOD_MASK;
     int aa = (d + bb - A_OFFSET) & MOD_MASK;
     *b = bb;
     *a = aa;
 }
 
 static void wav_decode(uint16_t *in, int nx, int ox,
                        int ny, int oy, uint16_t mx)
 {
     int w14 = (mx < (1 << 14));

     int n   = (nx > ny) ? ny : nx;
     int p   = 1;

     int p2;
 
     while (p <= n)
         p <<= 1;
 
     p >>= 1;
     p2  = p;
     p >>= 1;
 
     while (p >= 1) {
         uint16_t *py = in;
         uint16_t *ey = in + oy * (ny - p2);
         uint16_t i00, i01, i10, i11;
         int oy1 = oy * p;
         int oy2 = oy * p2;
         int ox1 = ox * p;
         int ox2 = ox * p2;
 
         for (; py <= ey; py += oy2) {
             uint16_t *px = py;
             uint16_t *ex = py + ox * (nx - p2);
 
             for (; px <= ex; px += ox2) {

                 uint16_t *p01 = px + ox1;
                 uint16_t *p10 = px + oy1;

                 uint16_t *p11 = p10 + ox1;
 
                 if (w14) {

                     wdec14(*px, *p10, &i00, &i10);

                     wdec14(*p01, *p11, &i01, &i11);

                     wdec14(i00, i01, px, p01);

                     wdec14(i10, i11, p10, p11);
                 } else {

                     wdec16(*px, *p10, &i00, &i10);

                     wdec16(*p01, *p11, &i01, &i11);

                     wdec16(i00, i01, px, p01);

                     wdec16(i10, i11, p10, p11);
                 }
             }
 
             if (nx & p) {
                 uint16_t *p10 = px + oy1;
 
                 if (w14)
                     wdec14(*px, *p10, &i00, p10);
                 else
                     wdec16(*px, *p10, &i00, p10);
 
                 *px = i00;
             }
         }
 
         if (ny & p) {
             uint16_t *px = py;
             uint16_t *ex = py + ox * (nx - p2);
 
             for (; px <= ex; px += ox2) {
                 uint16_t *p01 = px + ox1;
 
                 if (w14)
                     wdec14(*px, *p01, &i00, p01);
                 else
                     wdec16(*px, *p01, &i00, p01);
 
                 *px = i00;
             }
         }
 

         p2  = p;

         p >>= 1;
     }
 }
 

 static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize,
                           int dsize, EXRThreadData *td)

 {
     GetByteContext gb;
     uint16_t maxval, min_non_zero, max_non_zero;

     uint16_t *ptr;
     uint16_t *tmp = (uint16_t *)td->tmp;
     uint8_t *out;

     int ret, i, j;
 
     if (!td->bitmap)
         td->bitmap = av_malloc(BITMAP_SIZE);
     if (!td->lut)
         td->lut = av_malloc(1 << 17);

     if (!td->bitmap || !td->lut) {

         av_freep(&td->bitmap);
         av_freep(&td->lut);

         return AVERROR(ENOMEM);

     }

 
     bytestream2_init(&gb, src, ssize);
     min_non_zero = bytestream2_get_le16(&gb);
     max_non_zero = bytestream2_get_le16(&gb);
 
     if (max_non_zero >= BITMAP_SIZE)
         return AVERROR_INVALIDDATA;
 
     memset(td->bitmap, 0, FFMIN(min_non_zero, BITMAP_SIZE));
     if (min_non_zero <= max_non_zero)
         bytestream2_get_buffer(&gb, td->bitmap + min_non_zero,
                                max_non_zero - min_non_zero + 1);
     memset(td->bitmap + max_non_zero, 0, BITMAP_SIZE - max_non_zero);
 
     maxval = reverse_lut(td->bitmap, td->lut);
 

     ret = huf_uncompress(&gb, tmp, dsize / sizeof(uint16_t));

     if (ret)
         return ret;
 
     ptr = tmp;
     for (i = 0; i < s->nb_channels; i++) {
         EXRChannel *channel = &s->channels[i];
         int size = channel->pixel_type;
 
         for (j = 0; j < size; j++)

             wav_decode(ptr + j, s->xdelta, size, s->ysize,
                        s->xdelta * size, maxval);

         ptr += s->xdelta * s->ysize * size;
     }
 

     apply_lut(td->lut, tmp, dsize / sizeof(uint16_t));

 
     out = td->uncompressed_data;

     for (i = 0; i < s->ysize; i++)

         for (j = 0; j < s->nb_channels; j++) {
             uint16_t *in = tmp + j * s->xdelta * s->ysize + i * s->xdelta;
             memcpy(out, in, s->xdelta * 2);
             out += s->xdelta * 2;
         }
 
     return 0;
 }
 

 static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
                             int compressed_size, int uncompressed_size,
                             EXRThreadData *td)
 {
     unsigned long dest_len = uncompressed_size;
     const uint8_t *in = td->tmp;
     uint8_t *out;
     int c, i, j;
 
     if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
         dest_len != uncompressed_size)

         return AVERROR_INVALIDDATA;

 
     out = td->uncompressed_data;

     for (i = 0; i < s->ysize; i++)

         for (c = 0; c < s->nb_channels; c++) {
             EXRChannel *channel = &s->channels[c];
             const uint8_t *ptr[4];
             uint32_t pixel = 0;
 
             switch (channel->pixel_type) {
             case EXR_FLOAT:
                 ptr[0] = in;
                 ptr[1] = ptr[0] + s->xdelta;
                 ptr[2] = ptr[1] + s->xdelta;

                 in     = ptr[2] + s->xdelta;

 
                 for (j = 0; j < s->xdelta; ++j) {
                     uint32_t diff = (*(ptr[0]++) << 24) |
                                     (*(ptr[1]++) << 16) |

                                     (*(ptr[2]++) << 8);

                     pixel += diff;

                     bytestream_put_le32(&out, pixel);

                 }
                 break;
             case EXR_HALF:
                 ptr[0] = in;
                 ptr[1] = ptr[0] + s->xdelta;

                 in     = ptr[1] + s->xdelta;

                 for (j = 0; j < s->xdelta; j++) {

                     uint32_t diff = (*(ptr[0]++) << 8) | *(ptr[1]++);
 
                     pixel += diff;

                     bytestream_put_le16(&out, pixel);

                 }
                 break;
             default:

                 return AVERROR_INVALIDDATA;

             }
         }
 
     return 0;
 }
 

 static int decode_block(AVCodecContext *avctx, void *tdata,
                         int jobnr, int threadnr)
 {
     EXRContext *s = avctx->priv_data;

     AVFrame *const p = s->picture;

     EXRThreadData *td = &s->thread_data[threadnr];
     const uint8_t *channel_buffer[4] = { 0 };
     const uint8_t *buf = s->buf;
     uint64_t line_offset, uncompressed_size;
     uint32_t xdelta = s->xdelta;
     uint16_t *ptr_x;
     uint8_t *ptr;

     uint32_t data_size, line;

     const uint8_t *src;
     int axmax = (avctx->width - (s->xmax + 1)) * 2 * s->desc->nb_components;
     int bxmin = s->xmin * 2 * s->desc->nb_components;

     int i, x, buf_size = s->buf_size;

     float one_gamma = 1.0f / s->gamma;

     int ret;

     line_offset = AV_RL64(s->gb.buffer + jobnr * 8);

     // Check if the buffer has the required bytes needed from the offset
     if (line_offset > buf_size - 8)
         return AVERROR_INVALIDDATA;
 

     src  = buf + line_offset + 8;

     line = AV_RL32(src - 8);
     if (line < s->ymin || line > s->ymax)
         return AVERROR_INVALIDDATA;
 
     data_size = AV_RL32(src - 4);
     if (data_size <= 0 || data_size > buf_size)
         return AVERROR_INVALIDDATA;
 

     s->ysize          = FFMIN(s->scan_lines_per_block, s->ymax - line + 1);

     uncompressed_size = s->scan_line_size * s->ysize;

     if ((s->compression == EXR_RAW && (data_size != uncompressed_size ||

                                  line_offset > buf_size - uncompressed_size)) ||

         (s->compression != EXR_RAW && (data_size > uncompressed_size ||

                                  line_offset > buf_size - data_size))) {

         return AVERROR_INVALIDDATA;
     }
 
     if (data_size < uncompressed_size) {

         av_fast_padded_malloc(&td->uncompressed_data,
                               &td->uncompressed_size, uncompressed_size);

         av_fast_padded_malloc(&td->tmp, &td->tmp_size, uncompressed_size);
         if (!td->uncompressed_data || !td->tmp)
             return AVERROR(ENOMEM);
 

         ret = AVERROR_INVALIDDATA;
         switch (s->compression) {

         case EXR_ZIP1:
         case EXR_ZIP16:
             ret = zip_uncompress(src, data_size, uncompressed_size, td);
             break;

         case EXR_PIZ:
             ret = piz_uncompress(s, src, data_size, uncompressed_size, td);
             break;

         case EXR_PXR24:
             ret = pxr24_uncompress(s, src, data_size, uncompressed_size, td);
             break;

         case EXR_RLE:
             ret = rle_uncompress(src, data_size, uncompressed_size, td);

         }

         if (ret < 0) {
             av_log(avctx, AV_LOG_ERROR, "decode_block() failed.\n");
             return ret;
         }

         src = td->uncompressed_data;

     }
 

     channel_buffer[0] = src + xdelta * s->channel_offsets[0];
     channel_buffer[1] = src + xdelta * s->channel_offsets[1];
     channel_buffer[2] = src + xdelta * s->channel_offsets[2];
     if (s->channel_offsets[3] >= 0)
         channel_buffer[3] = src + xdelta * s->channel_offsets[3];
 

     ptr = p->data[0] + line * p->linesize[0];

     for (i = 0;
          i < s->scan_lines_per_block && line + i <= s->ymax;
          i++, ptr += p->linesize[0]) {

         const uint8_t *r, *g, *b, *a;
 
         r = channel_buffer[0];
         g = channel_buffer[1];
         b = channel_buffer[2];
         if (channel_buffer[3])
             a = channel_buffer[3];
 

         ptr_x = (uint16_t *) ptr;

 
         // Zero out the start if xmin is not 0
         memset(ptr_x, 0, bxmin);
         ptr_x += s->xmin * s->desc->nb_components;

         if (s->pixel_type == EXR_FLOAT) {

             // 32-bit
             for (x = 0; x < xdelta; x++) {

                 union av_intfloat32 t;
                 t.i = bytestream_get_le32(&r);

                 if (t.f > 0.0f)  /* avoid negative values */

                     t.f = powf(t.f, one_gamma);
                 *ptr_x++ = exr_flt2uint(t.i);
 
                 t.i = bytestream_get_le32(&g);

                 if (t.f > 0.0f)

                     t.f = powf(t.f, one_gamma);
                 *ptr_x++ = exr_flt2uint(t.i);
 
                 t.i = bytestream_get_le32(&b);

                 if (t.f > 0.0f)

                     t.f = powf(t.f, one_gamma);
                 *ptr_x++ = exr_flt2uint(t.i);

                 if (channel_buffer[3])
                     *ptr_x++ = exr_flt2uint(bytestream_get_le32(&a));
             }
         } else {
             // 16-bit
             for (x = 0; x < xdelta; x++) {

                 *ptr_x++ = s->gamma_table[bytestream_get_le16(&r)];
                 *ptr_x++ = s->gamma_table[bytestream_get_le16(&g)];
                 *ptr_x++ = s->gamma_table[bytestream_get_le16(&b)];

                 if (channel_buffer[3])
                     *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&a));
             }
         }
 
         // Zero out the end if xmax+1 is not w
         memset(ptr_x, 0, axmax);
 
         channel_buffer[0] += s->scan_line_size;
         channel_buffer[1] += s->scan_line_size;
         channel_buffer[2] += s->scan_line_size;
         if (channel_buffer[3])
             channel_buffer[3] += s->scan_line_size;
     }
 
     return 0;
 }
 

 /**
  * Check if the variable name corresponds to its data type.
  *
  * @param s              the EXRContext
  * @param value_name     name of the variable to check
  * @param value_type     type of the variable to check
  * @param minimum_length minimum length of the variable data
  *
  * @return bytes to read containing variable data
  *         -1 if variable is not found
  *         0 if buffer ended prematurely
  */
 static int check_header_variable(EXRContext *s,
                                  const char *value_name,
                                  const char *value_type,
                                  unsigned int minimum_length)

 {

     int var_size = -1;
 
     if (bytestream2_get_bytes_left(&s->gb) >= minimum_length &&
         !strcmp(s->gb.buffer, value_name)) {
         // found value_name, jump to value_type (null terminated strings)
         s->gb.buffer += strlen(value_name) + 1;
         if (!strcmp(s->gb.buffer, value_type)) {
             s->gb.buffer += strlen(value_type) + 1;
             var_size = bytestream2_get_le32(&s->gb);
             // don't go read past boundaries
             if (var_size > bytestream2_get_bytes_left(&s->gb))
                 var_size = 0;
         } else {
             // value_type not found, reset the buffer
             s->gb.buffer -= strlen(value_name) + 1;
             av_log(s->avctx, AV_LOG_WARNING,
                    "Unknown data type %s for header variable %s.\n",
                    value_type, value_name);
         }
     }

     return var_size;
 }

 static int decode_header(EXRContext *s)
 {
     int current_channel_offset = 0;
     int magic_number, version, flags, i;

     s->xmin               = ~0;
     s->xmax               = ~0;
     s->ymin               = ~0;
     s->ymax               = ~0;
     s->xdelta             = ~0;
     s->ydelta             = ~0;
     s->channel_offsets[0] = -1;
     s->channel_offsets[1] = -1;
     s->channel_offsets[2] = -1;
     s->channel_offsets[3] = -1;
     s->pixel_type         = EXR_UNKNOWN;
     s->compression        = EXR_UNKN;
     s->nb_channels        = 0;
     s->w                  = 0;
     s->h                  = 0;
 

     if (bytestream2_get_bytes_left(&s->gb) < 10) {
         av_log(s->avctx, AV_LOG_ERROR, "Header too short to parse.\n");

         return AVERROR_INVALIDDATA;

     }
 

     magic_number = bytestream2_get_le32(&s->gb);
     if (magic_number != 20000630) {
         /* As per documentation of OpenEXR, it is supposed to be
          * int 20000630 little-endian */
         av_log(s->avctx, AV_LOG_ERROR, "Wrong magic number %d.\n", magic_number);

         return AVERROR_INVALIDDATA;

     }
 

     version = bytestream2_get_byte(&s->gb);

     if (version != 2) {

         avpriv_report_missing_feature(s->avctx, "Version %d", version);

         return AVERROR_PATCHWELCOME;
     }
 

     flags = bytestream2_get_le24(&s->gb);
     if (flags & 0x02) {
         avpriv_report_missing_feature(s->avctx, "Tile support");

         return AVERROR_PATCHWELCOME;

     }
 
     // Parse the header

     while (bytestream2_get_bytes_left(&s->gb) > 0 && *s->gb.buffer) {
         int var_size;
         if ((var_size = check_header_variable(s, "channels",
                                               "chlist", 38)) >= 0) {
             GetByteContext ch_gb;
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             bytestream2_init(&ch_gb, s->gb.buffer, var_size);
 
             while (bytestream2_get_bytes_left(&ch_gb) >= 19) {

                 EXRChannel *channel;

                 enum ExrPixelType current_pixel_type;

                 int channel_index = -1;

                 int xsub, ysub;

                 if (strcmp(s->layer, "") != 0) {
                     if (strncmp(ch_gb.buffer, s->layer, strlen(s->layer)) == 0) {
                         ch_gb.buffer += strlen(s->layer);
                         if (*ch_gb.buffer == '.')
                             ch_gb.buffer++;         /* skip dot if not given */
                         av_log(s->avctx, AV_LOG_INFO,
                                "Layer %s.%s matched.\n", s->layer, ch_gb.buffer);

                     }
                 }
 

                 if (!strcmp(ch_gb.buffer, "R") ||
                     !strcmp(ch_gb.buffer, "X") ||
                     !strcmp(ch_gb.buffer, "U"))

                     channel_index = 0;

                 else if (!strcmp(ch_gb.buffer, "G") ||
                          !strcmp(ch_gb.buffer, "Y") ||
                          !strcmp(ch_gb.buffer, "V"))

                     channel_index = 1;

                 else if (!strcmp(ch_gb.buffer, "B") ||
                          !strcmp(ch_gb.buffer, "Z") ||
                          !strcmp(ch_gb.buffer, "W"))

                     channel_index = 2;

                 else if (!strcmp(ch_gb.buffer, "A"))

                     channel_index = 3;

                 else

                     av_log(s->avctx, AV_LOG_WARNING,
                            "Unsupported channel %.256s.\n", ch_gb.buffer);

                 /* skip until you get a 0 */
                 while (bytestream2_get_bytes_left(&ch_gb) > 0 &&
                        bytestream2_get_byte(&ch_gb))
                     continue;

                 if (bytestream2_get_bytes_left(&ch_gb) < 4) {
                     av_log(s->avctx, AV_LOG_ERROR, "Incomplete header.\n");

                     return AVERROR_INVALIDDATA;

                 }
 

                 current_pixel_type = bytestream2_get_le32(&ch_gb);
                 if (current_pixel_type >= EXR_UNKNOWN) {
                     avpriv_report_missing_feature(s->avctx,
                                                   "Pixel type %d.\n",
                                                   current_pixel_type);
                     return AVERROR_PATCHWELCOME;

                 }
 

                 bytestream2_skip(&ch_gb, 4);
                 xsub = bytestream2_get_le32(&ch_gb);
                 ysub = bytestream2_get_le32(&ch_gb);

                 if (xsub != 1 || ysub != 1) {

                     avpriv_report_missing_feature(s->avctx,
                                                   "Subsampling %dx%d",
                                                   xsub, ysub);

                     return AVERROR_PATCHWELCOME;
                 }
 

                 if (channel_index >= 0) {

                     if (s->pixel_type != EXR_UNKNOWN &&
                         s->pixel_type != current_pixel_type) {
                         av_log(s->avctx, AV_LOG_ERROR,
                                "RGB channels not of the same depth.\n");

                         return AVERROR_INVALIDDATA;

                     }

                     s->pixel_type                     = current_pixel_type;

                     s->channel_offsets[channel_index] = current_channel_offset;
                 }
 

                 s->channels = av_realloc(s->channels,
                                          ++s->nb_channels * sizeof(EXRChannel));

                 if (!s->channels)
                     return AVERROR(ENOMEM);

                 channel             = &s->channels[s->nb_channels - 1];

                 channel->pixel_type = current_pixel_type;

                 channel->xsub       = xsub;
                 channel->ysub       = ysub;

                 current_channel_offset += 1 << current_pixel_type;

             }
 
             /* Check if all channels are set with an offset or if the channels
              * are causing an overflow  */
             if (FFMIN3(s->channel_offsets[0],
                        s->channel_offsets[1],
                        s->channel_offsets[2]) < 0) {
                 if (s->channel_offsets[0] < 0)

                     av_log(s->avctx, AV_LOG_ERROR, "Missing red channel.\n");

                 if (s->channel_offsets[1] < 0)

                     av_log(s->avctx, AV_LOG_ERROR, "Missing green channel.\n");

                 if (s->channel_offsets[2] < 0)

                     av_log(s->avctx, AV_LOG_ERROR, "Missing blue channel.\n");

                 return AVERROR_INVALIDDATA;

             }
 

             // skip one last byte and update main gb
             s->gb.buffer = ch_gb.buffer + 1;

             continue;

         } else if ((var_size = check_header_variable(s, "dataWindow", "box2i",
                                                      31)) >= 0) {
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             s->xmin   = bytestream2_get_le32(&s->gb);
             s->ymin   = bytestream2_get_le32(&s->gb);
             s->xmax   = bytestream2_get_le32(&s->gb);
             s->ymax   = bytestream2_get_le32(&s->gb);

             s->xdelta = (s->xmax - s->xmin) + 1;
             s->ydelta = (s->ymax - s->ymin) + 1;

 
             continue;

         } else if ((var_size = check_header_variable(s, "displayWindow",
                                                      "box2i", 34)) >= 0) {
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             bytestream2_skip(&s->gb, 8);
             s->w = bytestream2_get_le32(&s->gb) + 1;
             s->h = bytestream2_get_le32(&s->gb) + 1;

 
             continue;

         } else if ((var_size = check_header_variable(s, "lineOrder",
                                                      "lineOrder", 25)) >= 0) {
             int line_order;
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             line_order = bytestream2_get_byte(&s->gb);
             av_log(s->avctx, AV_LOG_DEBUG, "line order: %d.\n", line_order);
             if (line_order > 2) {
                 av_log(s->avctx, AV_LOG_ERROR, "Unknown line order.\n");

                 return AVERROR_INVALIDDATA;

             }
 
             continue;

         } else if ((var_size = check_header_variable(s, "pixelAspectRatio",
                                                      "float", 31)) >= 0) {
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             ff_set_sar(s->avctx,
                        av_d2q(av_int2float(bytestream2_get_le32(&s->gb)), 255));

 
             continue;

         } else if ((var_size = check_header_variable(s, "compression",
                                                      "compression", 29)) >= 0) {
             if (!var_size)

                 return AVERROR_INVALIDDATA;

             if (s->compression == EXR_UNKN)
                 s->compression = bytestream2_get_byte(&s->gb);

             else

                 av_log(s->avctx, AV_LOG_WARNING,
                        "Found more than one compression attribute.\n");

 
             continue;
         }
 

         // Check if there are enough bytes for a header
         if (bytestream2_get_bytes_left(&s->gb) <= 9) {
             av_log(s->avctx, AV_LOG_ERROR, "Incomplete header\n");

             return AVERROR_INVALIDDATA;

         }
 
         // Process unknown variables

         for (i = 0; i < 2; i++) // value_name and value_type
             while (bytestream2_get_byte(&s->gb) != 0);
 

         // Skip variable length

         bytestream2_skip(&s->gb, bytestream2_get_le32(&s->gb));

     }
 

     if (s->compression == EXR_UNKN) {
         av_log(s->avctx, AV_LOG_ERROR, "Missing compression attribute.\n");

         return AVERROR_INVALIDDATA;
     }

     s->scan_line_size = s->xdelta * current_channel_offset;

     if (bytestream2_get_bytes_left(&s->gb) <= 0) {
         av_log(s->avctx, AV_LOG_ERROR, "Incomplete frame.\n");

         return AVERROR_INVALIDDATA;

     }

 
     // aaand we are done
     bytestream2_skip(&s->gb, 1);
     return 0;
 }
 
 static int decode_frame(AVCodecContext *avctx, void *data,
                         int *got_frame, AVPacket *avpkt)
 {
     EXRContext *s = avctx->priv_data;
     ThreadFrame frame = { .f = data };
     AVFrame *picture = data;
     uint8_t *ptr;
 
     int y, ret;
     int out_line_size;
     int scan_line_blocks;
 
     bytestream2_init(&s->gb, avpkt->data, avpkt->size);
 
     if ((ret = decode_header(s)) < 0)
         return ret;

     switch (s->pixel_type) {
     case EXR_FLOAT:
     case EXR_HALF:

         if (s->channel_offsets[3] >= 0)

             avctx->pix_fmt = AV_PIX_FMT_RGBA64;

         else

             avctx->pix_fmt = AV_PIX_FMT_RGB48;

         break;

     case EXR_UINT:

         avpriv_request_sample(avctx, "32-bit unsigned int");

         return AVERROR_PATCHWELCOME;

     default:

         av_log(avctx, AV_LOG_ERROR, "Missing channel list.\n");

         return AVERROR_INVALIDDATA;

     }
 

     switch (s->compression) {

     case EXR_RAW:

     case EXR_RLE:

     case EXR_ZIP1:

         s->scan_lines_per_block = 1;

         break;

     case EXR_PXR24:

     case EXR_ZIP16:

         s->scan_lines_per_block = 16;

         break;

     case EXR_PIZ:
         s->scan_lines_per_block = 32;
         break;

     default:

         avpriv_report_missing_feature(avctx, "Compression %d", s->compression);

         return AVERROR_PATCHWELCOME;

     }
 

     /* Verify the xmin, xmax, ymin, ymax and xdelta before setting
      * the actual image size. */
     if (s->xmin > s->xmax                  ||
         s->ymin > s->ymax                  ||

         s->xdelta != s->xmax - s->xmin + 1 ||

         s->xmax >= s->w                    ||
         s->ymax >= s->h) {
         av_log(avctx, AV_LOG_ERROR, "Wrong or missing size information.\n");

         return AVERROR_INVALIDDATA;

     }
 

     if ((ret = ff_set_dimensions(avctx, s->w, s->h)) < 0)

         return ret;

     s->desc          = av_pix_fmt_desc_get(avctx->pix_fmt);
     if (!s->desc)
         return AVERROR_INVALIDDATA;
     out_line_size    = avctx->width * 2 * s->desc->nb_components;
     scan_line_blocks = (s->ydelta + s->scan_lines_per_block - 1) /
                        s->scan_lines_per_block;

     if ((ret = ff_thread_get_buffer(avctx, &frame, 0)) < 0)

         return ret;

     if (bytestream2_get_bytes_left(&s->gb) < scan_line_blocks * 8)

         return AVERROR_INVALIDDATA;

 
     // save pointer we are going to use in decode_block
     s->buf      = avpkt->data;
     s->buf_size = avpkt->size;
     ptr         = picture->data[0];

 
     // Zero out the start if ymin is not 0

     for (y = 0; y < s->ymin; y++) {

         memset(ptr, 0, out_line_size);

         ptr += picture->linesize[0];

     }
 

     s->picture = picture;

     avctx->execute2(avctx, decode_block, s->thread_data, NULL, scan_line_blocks);

 
     // Zero out the end if ymax+1 is not h

     for (y = s->ymax + 1; y < avctx->height; y++) {

         memset(ptr, 0, out_line_size);

         ptr += picture->linesize[0];

     }
 

     picture->pict_type = AV_PICTURE_TYPE_I;

     *got_frame = 1;

     return avpkt->size;
 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     EXRContext *s = avctx->priv_data;

     uint32_t i;
     union av_intfloat32 t;
     float one_gamma = 1.0f / s->gamma;

 
     s->avctx              = avctx;
 

     if (one_gamma > 0.9999f && one_gamma < 1.0001f) {
         for (i = 0; i < 65536; ++i)

             s->gamma_table[i] = exr_halflt2uint(i);
     } else {

         for (i = 0; i < 65536; ++i) {

             t = exr_half2float(i);
             /* If negative value we reuse half value */

             if (t.f <= 0.0f) {

                 s->gamma_table[i] = exr_halflt2uint(i);
             } else {
                 t.f = powf(t.f, one_gamma);
                 s->gamma_table[i] = exr_flt2uint(t.i);
             }
         }
     }
 

     // allocate thread data, used for non EXR_RAW compreesion types
     s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
     if (!s->thread_data)
         return AVERROR_INVALIDDATA;
 
     return 0;
 }
 
 static int decode_init_thread_copy(AVCodecContext *avctx)
 {    EXRContext *s = avctx->priv_data;
 
     // allocate thread data, used for non EXR_RAW compreesion types
     s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
     if (!s->thread_data)
         return AVERROR_INVALIDDATA;
 
     return 0;

 }
 
 static av_cold int decode_end(AVCodecContext *avctx)
 {
     EXRContext *s = avctx->priv_data;

     int i;

     for (i = 0; i < avctx->thread_count; i++) {

         EXRThreadData *td = &s->thread_data[i];

         av_freep(&td->uncompressed_data);
         av_freep(&td->tmp);
         av_freep(&td->bitmap);
         av_freep(&td->lut);

     }
 
     av_freep(&s->thread_data);

     av_freep(&s->channels);

     return 0;
 }
 

 #define OFFSET(x) offsetof(EXRContext, x)
 #define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     { "layer", "Set the decoding layer", OFFSET(layer),
         AV_OPT_TYPE_STRING, { .str = "" }, 0, 0, VD },

     { "gamma", "Set the float gamma value when decoding", OFFSET(gamma),

         AV_OPT_TYPE_FLOAT, { .dbl = 1.0f }, 0.001, FLT_MAX, VD },

     { NULL },
 };
 
 static const AVClass exr_class = {
     .class_name = "EXR",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVCodec ff_exr_decoder = {

     .name             = "exr",
     .long_name        = NULL_IF_CONFIG_SMALL("OpenEXR image"),
     .type             = AVMEDIA_TYPE_VIDEO,
     .id               = AV_CODEC_ID_EXR,
     .priv_data_size   = sizeof(EXRContext),
     .init             = decode_init,
     .init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
     .close            = decode_end,
     .decode           = decode_frame,

     .capabilities     = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS |
                         AV_CODEC_CAP_SLICE_THREADS,

     .priv_class       = &exr_class,

 };