avcodec/mpegaudio_tablegen: Make exponential LUT shared

Both the fixed as well as the floating point mpegaudio decoders use
LUTs of type int8_t and uint32_t with 32K entries each; these tables
are completely the same, yet they are not shared. This commit makes
them shared. When both fixed as well as floating point decoders are
enabled, this saves 160KiB from the bss segment for a normal build
(translating into 160KiB less memory usage if both a shared as well as
a floating point decoder have actually been used) and 160KiB from the
binary for a build with hardcoded tables.

It also means that the code to create said LUTs is no longer duplicated
(for a normal build).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/libavcodec/mpegaudiodec_common_tablegen.c b/libavcodec/mpegaudiodec_common_tablegen.c
new file mode 100644
index 0000000000..a319df65ab
--- /dev/null
+++ b/libavcodec/mpegaudiodec_common_tablegen.c
@@ -0,0 +1,40 @@
+/*
+ * Generate a header file for hardcoded shared mpegaudiodec tables
+ *
+ * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
+ * Copyright (c) 2020 Andreas Rheinhardt <andreas.rheinhardt@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
+ */
+
+#include <stdlib.h>
+#define CONFIG_HARDCODED_TABLES 0
+#include "libavutil/tablegen.h"
+#include "mpegaudiodec_common_tablegen.h"
+#include "tableprint.h"
+
+int main(void)
+{
+    mpegaudiodec_common_tableinit();
+
+    write_fileheader();
+
+    WRITE_ARRAY("const", int8_t, ff_table_4_3_exp);
+    WRITE_ARRAY("const", uint32_t, ff_table_4_3_value);
+
+    return 0;
+}