ARM: fail build if hardcoded struct offsets are wrong

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@23427 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/arm/asm-offsets.h

+/*
+ * Copyright (c) 2010 Mans Rullgard
+ *
+ * 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
+ */
+
+#ifndef AVCODEC_ARM_ASM_OFFSETS_H
+#define AVCODEC_ARM_ASM_OFFSETS_H
+
+#ifndef __ASSEMBLER__
+#include <stddef.h>
+#define CHK_OFFS(s, m, o) struct check_##o {    \
+        int x_##o[offsetof(s, m) == o? 1: -1];  \
+    }
+#endif
+
+/* MpegEncContext */
+#define Y_DC_SCALE               0xa54
+#define C_DC_SCALE               0xa58
+#define AC_PRED                  0xa80
+#define BLOCK_LAST_INDEX         0x2278
+#define INTER_SCANTAB_RASTER_END 0x2478
+#define H263_AIC                 0x2728
+
+#endif

libavcodec/arm/mpegvideo_arm.c

@@ -22,6 +22,14 @@
 #include "libavcodec/dsputil.h"
 #include "libavcodec/mpegvideo.h"
 #include "mpegvideo_arm.h"
+#include "asm-offsets.h"
+
+CHK_OFFS(MpegEncContext, y_dc_scale,       Y_DC_SCALE);
+CHK_OFFS(MpegEncContext, c_dc_scale,       C_DC_SCALE);
+CHK_OFFS(MpegEncContext, ac_pred,          AC_PRED);
+CHK_OFFS(MpegEncContext, block_last_index, BLOCK_LAST_INDEX);
+CHK_OFFS(MpegEncContext, inter_scantable.raster_end, INTER_SCANTAB_RASTER_END);
+CHK_OFFS(MpegEncContext, h263_aic,         H263_AIC);
 
 void ff_dct_unquantize_h263_inter_neon(MpegEncContext *s, DCTELEM *block,
                                        int n, int qscale);

libavcodec/arm/mpegvideo_neon.S

@@ -19,13 +19,7 @@
  */
 
 #include "asm.S"
-
-#define Y_DC_SCALE               0xa54
-#define C_DC_SCALE               0xa58
-#define AC_PRED                  0xa80
-#define BLOCK_LAST_INDEX         0x2278
-#define INTER_SCANTAB_RASTER_END 0x2478
-#define H263_AIC                 0x2728
+#include "asm-offsets.h"
 
 function ff_dct_unquantize_h263_inter_neon, export=1
         add             r0,  r0,  #0x2200