SWIG generates invalid code

[SwigAtSF]

• Artifact_id: 1534564
• Opened: 2006-08-04 16:03:58 +0200
• Submitter: Reinhard Hemmerling <hardy2006@users.sf.net>
• Assignee: David M. Beazley <beazley@users.sf.net>

The goal was to generate a wrapper for the ffmpeg-library in Java.

1) checkout the ffmpeg sources 2) compile ffmpeg. 3) generate wrapper sources (Java and C) 4) compile native part of wrapper

Those steps are performed by the attached shell script. The interface definition file looks like this:

(right now just for one of the headers)

%module ffmpeg

%{ /* Includes the header in the wrapper code */

include "ffmpeg/avcodec.h"

%}

/* Parse the header file to generate wrappers */

%include "ffmpeg-linux/include/ffmpeg/avcodec.h"

Running the script results in these error messages:

$ ./generate.sh ffmpeg-linux/include/ffmpeg/avcodec.h:25: Warning(305): Bad constant value (ignored). ffmpeg-linux/include/ffmpeg/avcodec.h:601: Warning(451): Setting a const char * variable may leak memory. ffmpeg-linux/include/ffmpeg/avcodec.h:1945: Warning(451): Setting a const char * variable may leak memory. temp/ffmpeg_wrap.c: In function 'Java_videal_wrapper_ffmpeg_ffmpegJNI_AVFrame_1motion_1val_1set': temp/ffmpeg_wrap.c:2394: error: expected identifier or '(' before ')' token temp/ffmpeg_wrap.c:2395: error: 'b' undeclared (first use in this function) temp/ffmpeg_wrap.c:2395: error: (Each undeclared identifier is reported only once temp/ffmpeg_wrap.c:2395: error: for each function it appears in.) temp/ffmpeg_wrap.c:2395: error: expected ')' before '*'

token

The problematic code that was generated:

JNIEXPORT void JNICALL Java_videal_wrapper_ffmpeg_ffmpegJNI_AVFrame_1motion_1val_1set(JNIEnv _jenv, jclass jcls, jlong jarg1, jlong jarg2) { AVFrame arg1 = (AVFrame ) 0 ; int16t (*arg2)[2] ;

(void)jenv; (void)jcls; arg1 = (AVFrame *)&jarg1; arg2 = _(int16t (_)[2])&jarg2; { size_t ii; int16t ()[2] _b = (int16t ()[2] _) arg1->motion_val; for (ii = 0; ii < (size_t)2; ii++) b[ii] = ((int16t ()[2] *) arg2 + ii); }

}

Seems the generation of this line does not work as expected: int16t ()[2] b = (int16t ()[2] ) rg1->motion_val;

Uncommenting that line and the next one, and the native part of the wrapper compiles.

Configuration of the linux system: swig 1.3.29 gcc 4.1.1

[SwigAtSF]

• Date: 2006-08-04 16:03:58 +0200
• From: Reinhard Hemmerling <hardy2006@users.sf.net>
• Added: generate.sh

[SwigAtSF]

• Date: 2006-10-12 22:55:33 +0200
• From: William Fulton <wsfulton@users.sf.net>

Logged In: YES user_id=242951

The cutdown source for this troublesome code is below and fails for all languages one way or another.

define FF_COMMON_FRAME

/*_\
 \* Motion vector table.\
 \* @code\
 \* example:\
 \* int mv_sample_log2= 4 - motion_subsample_log2;\
 \* int mb_width= (width+15)>>4;\
 \* int mv_stride= (mb_width << mv_sample_log2) + 1;\
 \* motion_val[direction][x + y*mv_stride][0->mv_x,

1->mv_y];\ * @endcode\ * - encoding: set by user\ * - decoding: set by lavc\ */\ int16_t (_motion_val[2])[2];\

typedef struct AVFrame { FF_COMMON_FRAME } AVFrame;

Egad, what is it?? :)