avcodec: add xbm parser

1 files changed, 101 insertions, 0 deletions

diff --git a/libavcodec/xbm_parser.c b/libavcodec/xbm_parser.c
new file mode 100644
index 0000000000..30d23200db
--- /dev/null
+++ b/libavcodec/xbm_parser.c
@@ -0,0 +1,101 @@
+/*
+ * XBM parser
+ * Copyright (c) 2021 Paul B Mahol
+ *
+ * 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
+ * XBM parser
+ */
+
+#include "libavutil/common.h"
+
+#include "parser.h"
+
+typedef struct XBMParseContext {
+    ParseContext pc;
+    uint16_t state16;
+    int count;
+} XBMParseContext;
+
+#define KEY (((uint64_t)'\n' << 56) | ((uint64_t)'#' << 48) | ((uint64_t)'d' << 40) | ((uint64_t)'e' << 32) | ((uint64_t)'f' << 24) | ('i' << 16) | ('n' << 8) | ('e' << 0))
+#define END ((';' << 8) | ('\n' << 0))
+
+static int xbm_init(AVCodecParserContext *s)
+{
+    XBMParseContext *bpc = s->priv_data;
+
+    bpc->count = 1;
+
+    return 0;
+}
+
+static int xbm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
+                     const uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size)
+{
+    XBMParseContext *bpc = s->priv_data;
+    uint64_t state = bpc->pc.state64;
+    uint16_t state16 = bpc->state16;
+    int next = END_NOT_FOUND, i = 0;
+
+    s->pict_type = AV_PICTURE_TYPE_NONE;
+    s->duration  = 1;
+
+    *poutbuf_size = 0;
+    *poutbuf = NULL;
+
+    for (; i < buf_size; i++) {
+        state = (state << 8) | buf[i];
+        state16 = (state16 << 8) | buf[i];
+
+        if (state == KEY)
+            bpc->count++;
+
+        if ((state == KEY && bpc->count == 1)) {
+            next = i - 6;
+            break;
+        } else if (state16 == END) {
+            next = i + 1;
+            bpc->count = 0;
+            break;
+        }
+    }
+
+    bpc->pc.state64 = state;
+    bpc->state16 = state16;
+    if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0) {
+        *poutbuf = NULL;
+        *poutbuf_size = 0;
+        return buf_size;
+    }
+
+    *poutbuf      = buf;
+    *poutbuf_size = buf_size;
+
+    return next;
+}
+
+AVCodecParser ff_xbm_parser = {
+    .codec_ids      = { AV_CODEC_ID_XBM },
+    .priv_data_size = sizeof(XBMParseContext),
+    .parser_init    = xbm_init,
+    .parser_parse   = xbm_parse,
+    .parser_close   = ff_parse_close,
+};