hap: Add utility functions file

Missing from the push of 3ee21785.

libavcodec/hap.c

+/*
+ * Vidvox Hap utility functions
+ * Copyright (C) 2015 Tom Butterworth <bangnoise@gmail.com>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Hap utilities
+ */
+#include "hap.h"
+
+int ff_hap_set_chunk_count(HapContext *ctx, int count, int first_in_frame)
+{
+    int ret = 0;
+    if (first_in_frame == 1 && ctx->chunk_count != count) {
+        int ret = av_reallocp_array(&ctx->chunks, count, sizeof(HapChunk));
+        if (ret == 0)
+            ret = av_reallocp_array(&ctx->chunk_results, count, sizeof(int));
+        if (ret < 0) {
+            ctx->chunk_count = 0;
+        } else {
+            ctx->chunk_count = count;
+        }
+    } else if (ctx->chunk_count != count) {
+        /* If this is not the first chunk count calculated for a frame and a
+         * different count has already been encountered, then reject the frame:
+         * each table in the Decode Instructions Container must describe the
+         * same number of chunks. */
+        ret = AVERROR_INVALIDDATA;
+    }
+    return ret;
+}
+
+av_cold void ff_hap_free_context(HapContext *ctx)
+{
+    av_freep(&ctx->tex_buf);
+    av_freep(&ctx->chunks);
+    av_freep(&ctx->chunk_results);
+}