@@ -71,6 +71,7 @@ version <next>:

 - FFmpeg metadata format muxer and demuxer

 - SubRip (srt) subtitle decoder

 - floating-point AC-3 encoder added

+- Lagarith decoder

 version 0.6:

@@ -424,6 +424,7 @@ following image formats are supported:

     @tab Codec used in Worms games.

 @item Kega Game Video (KGV1) @tab      @tab  X

     @tab Kega emulator screen capture codec.

+@item Lagarith               @tab     @tab  X

 @item LCL (LossLess Codec Library) MSZH  @tab     @tab  X

 @item LCL (LossLess Codec Library) ZLIB  @tab  E  @tab  E

 @item LOCO                   @tab     @tab  X

@@ -185,6 +185,7 @@ OBJS-$(CONFIG_JPEGLS_DECODER)          += jpeglsdec.o jpegls.o \

 OBJS-$(CONFIG_JPEGLS_ENCODER)          += jpeglsenc.o jpegls.o

 OBJS-$(CONFIG_KGV1_DECODER)            += kgv1dec.o

 OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o

+OBJS-$(CONFIG_LAGARITH_DECODER)        += lagarith.o lagarithrac.o

 OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc.o mjpeg.o \

                                           mpegvideo_enc.o motion_est.o  \

                                           ratecontrol.o mpeg12data.o    \

@@ -128,6 +128,7 @@ void avcodec_register_all(void)

     REGISTER_ENCDEC  (JPEGLS, jpegls);

     REGISTER_DECODER (KGV1, kgv1);

     REGISTER_DECODER (KMVC, kmvc);

+    REGISTER_DECODER (LAGARITH, lagarith);

     REGISTER_ENCODER (LJPEG, ljpeg);

     REGISTER_DECODER (LOCO, loco);

     REGISTER_DECODER (MDEC, mdec);

@@ -32,7 +32,7 @@

 #include "libavutil/cpu.h"

 #define LIBAVCODEC_VERSION_MAJOR 52

-#define LIBAVCODEC_VERSION_MINOR 107

+#define LIBAVCODEC_VERSION_MINOR 108

 #define LIBAVCODEC_VERSION_MICRO  0

 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \

@@ -259,6 +259,7 @@ enum CodecID {

     CODEC_ID_A64_MULTI5,

     CODEC_ID_R10K,

     CODEC_ID_MXPEG,

+    CODEC_ID_LAGARITH,

     /* various PCM "codecs" */

     CODEC_ID_PCM_S16LE= 0x10000,

new file mode 100644

@@ -0,0 +1,518 @@

+/*

+ * 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 libavcodec/lagarith.c

+ * Lagarith lossless decoder

+ * @author Nathan Caldwell

+ */

+

+#include "avcodec.h"

+#include "get_bits.h"

+#include "mathops.h"

+#include "dsputil.h"

+#include "lagarithrac.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 */

+} 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 > 257 - i)

+                prob = 257 - 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 negligable and fixing it

+             *                          // breaks backwards compatibilty

+             *      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 + 1, buf + 1,

+                                            width - 1, buf[0]);

+        return;

+    } else if (line == 1) {

+        /* Second line, left predict first pixel, the rest of the line is median predicted */

+        /* FIXME: In the case of RGB this pixel is top predicted */

+        TL = buf[-stride];

+    } else {

+        /* Top left is 2 rows back, last pixel */

+        TL = buf[width - (2 * stride) - 1];

+    }

+    /* Left pixel is actually prev_row[width] */

+    L = buf[width - stride - 1];

+

+    add_lag_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, int width,

+                                    int esc_count)

+{

+    int i = 0;

+    int count;

+    uint8_t zero_run = 0;

+    const uint8_t *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);

+        memset(dst, 0, count);

+        l->zeros_rem -= count;

+        dst += count;

+    }

+

+    while (dst < end) {

+        i = 0;

+        while (!zero_run && dst + i < end) {

+            i++;

+            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;

+        }

+    }

+    return start - src;

+}

+

+

+

+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 = src[0];

+    GetBitContext gb;

+    lag_rac rac;

+

+    rac.avctx = l->avctx;

+    l->zeros = 0;

+

+    if (esc_count < 4) {

+        length = width * height;

+        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;

+

+        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++)

+                src += lag_decode_zero_run_line(l, dst + (i * stride), src,

+                                                width, esc_count);

+        } else {

+            /* 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 0 bytes */

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

+            memset(dst + i * stride, 0, width);

+    } else {

+        av_log(l->avctx, AV_LOG_ERROR,

+               "Invalid zero run escape code! (%#x)\n", esc_count);

+        return -1;

+    }

+

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

+        lag_pred_line(l, dst, width, stride, i);

+        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 *data_size, AVPacket *avpkt)

+{

+    const uint8_t *buf = avpkt->data;

+    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;

+

+    AVFrame *picture = data;

+

+    if (p->data[0])

+        avctx->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_ARITH_YV12:

+        avctx->pix_fmt = PIX_FMT_YUV420P;

+

+        if (avctx->get_buffer(avctx, p) < 0) {

+            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

+            return -1;

+        }

+

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

+                               p->linesize[0], buf + offset_ry,

+                               buf_size);

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

+                               avctx->height / 2, p->linesize[2],

+                               buf + offset_gu, buf_size);

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

+                               avctx->height / 2, p->linesize[1],

+                               buf + offset_bv, buf_size);

+        break;

+    default:

+        av_log(avctx, AV_LOG_ERROR,

+               "Unsupported Lagarith frame type: %#x\n", frametype);

+        return -1;

+    }

+

+    *picture = *p;

+    *data_size = sizeof(AVFrame);

+

+    return buf_size;

+}

+

+static av_cold int lag_decode_init(AVCodecContext *avctx)

+{

+    LagarithContext *l = avctx->priv_data;

+    l->avctx = avctx;

+

+    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])

+        avctx->release_buffer(avctx, &l->picture);

+

+    return 0;

+}

+

+AVCodec lagarith_decoder = {

+    "lagarith",

+    CODEC_TYPE_VIDEO,

+    CODEC_ID_LAGARITH,

+    sizeof(LagarithContext),

+    lag_decode_init,

+    NULL,

+    lag_decode_end,

+    lag_decode_frame,

+    CODEC_CAP_DR1,

+    .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),

+};

new file mode 100644

@@ -0,0 +1,58 @@

+/*

+ * Lagarith range decoder

+ * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>

+ * Copyright (c) 2009 David Conrad

+ *

+ * 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/lagarithrac.c

+ * Lagarith range decoder

+ * @author Nathan Caldwell

+ * @author David Conrad

+ */

+

+#include "get_bits.h"

+#include "lagarithrac.h"

+

+void lag_rac_init(lag_rac *l, GetBitContext *gb, int length)

+{

+    int i, j;

+

+    /* According to reference decoder "1st byte is garbage",

+     * however, it gets skipped by the call to align_get_bits()

+     */

+    align_get_bits(gb);

+    l->bytestream_start =

+    l->bytestream       = gb->buffer + get_bits_count(gb) / 8;

+    l->bytestream_end   = l->bytestream_start + length;

+

+    l->range        = 0x80;

+    l->low          = *l->bytestream >> 1;

+    l->hash_shift   = FFMAX(l->scale - 8, 0);

+

+    for (i = j = 0; i < 256; i++) {

+        unsigned r = i << l->hash_shift;

+        while (l->prob[j + 1] <= r)

+            j++;

+        l->range_hash[i] = j;

+    }

+

+    /* Add conversion factor to hash_shift so we don't have to in lag_get_rac. */

+    l->hash_shift += 23;

+}

new file mode 100644

@@ -0,0 +1,116 @@

+/*

+ * Lagarith range decoder

+ * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>

+ * Copyright (c) 2009 David Conrad

+ *

+ * 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/lagarithrac.h

+ * Lagarith range decoder

+ * @author Nathan Caldwell

+ * @author David Conrad

+ */

+

+#ifndef AVCODEC_LAGARITHRAC_H

+#define AVCODEC_LAGARITHRAC_H

+

+#include <stdint.h>

+#include "libavutil/common.h"

+#include "libavutil/intreadwrite.h"

+#include "avcodec.h"

+#include "get_bits.h"

+

+typedef struct lag_rac {

+    AVCodecContext *avctx;

+    unsigned low;

+    unsigned range;

+    unsigned scale;             /*!< Number of bits of precision in range. */

+    unsigned hash_shift;        /*!< Number of bits to shift to calculate hash for radix search. */

+

+    const uint8_t *bytestream_start;  /*!< Start of input bytestream. */

+    const uint8_t *bytestream;        /*!< Current position in input bytestream. */

+    const uint8_t *bytestream_end;    /*!< End position of input bytestream. */

+

+    uint32_t prob[258];         /*!< Table of cumulative probability for each symbol. */

+    uint8_t  range_hash[256];   /*!< Hash table mapping upper byte to approximate symbol. */

+} lag_rac;

+

+void lag_rac_init(lag_rac *l, GetBitContext *gb, int length);

+

+/* TODO: Optimize */

+static inline void lag_rac_refill(lag_rac *l)

+{

+    while (l->range <= 0x800000) {

+        l->low   <<= 8;

+        l->range <<= 8;

+        l->low |= 0xff & (AV_RB16(l->bytestream) >> 1);

+        if (l->bytestream < l->bytestream_end)

+            l->bytestream++;

+    }

+}

+

+/**

+ * Decode a single byte from the compressed plane described by *l.

+ * @param l pointer to lag_rac for the current plane

+ * @return next byte of decoded data

+ */

+static inline uint8_t lag_get_rac(lag_rac *l)

+{

+    unsigned range_scaled, low_scaled, div;

+    int val;

+    uint8_t shift;

+

+    lag_rac_refill(l);

+

+    range_scaled = l->range >> l->scale;

+

+    if (l->low < range_scaled * l->prob[255]) {

+        /* val = 0 is frequent enough to deserve a shortcut */

+        if (l->low < range_scaled * l->prob[1]) {

+            val = 0;

+        } else {

+            /* FIXME __builtin_clz is ~20% faster here, but not allowed in generic code. */

+            shift = 30 - av_log2(range_scaled);

+            div = ((range_scaled << shift) + (1 << 23) - 1) >> 23;

+            /* low>>24 ensures that any cases too big for exact FASTDIV are

+             * under- rather than over-estimated

+             */

+            low_scaled = FASTDIV(l->low - (l->low >> 24), div);

+            shift -= l->hash_shift;

+            shift &= 31;

+            low_scaled = (low_scaled << shift) | (low_scaled >> (32 - shift));

+            /* low_scaled is now a lower bound of low/range_scaled */

+            val = l->range_hash[(uint8_t) low_scaled];

+            while (l->low >= range_scaled * l->prob[val + 1])

+                val++;

+        }

+

+        l->range = range_scaled * (l->prob[val + 1] - l->prob[val]);

+    } else {

+        val = 255;

+        l->range -= range_scaled * l->prob[255];

+    }

+

+    l->low -= range_scaled * l->prob[val];

+

+    return val;

+}

+

+

+#endif /* AVCODEC_LAGARITHRAC_H */

@@ -257,6 +257,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {

     { CODEC_ID_AURA2,        MKTAG('A', 'U', 'R', '2') },

     { CODEC_ID_DPX,          MKTAG('d', 'p', 'x', ' ') },

     { CODEC_ID_KGV1,         MKTAG('K', 'G', 'V', '1') },

+    { CODEC_ID_LAGARITH,     MKTAG('L', 'A', 'G', 'S') },

     { CODEC_ID_NONE,         0 }

 };