Hi there!

I'm trying to compile libjpeg to JavaScript for using it in a webapp. So 
far I've had no luck with getting it to work. What I've done:

1. I've set up emscripten with my Ubuntu 14.04 LTS, the simple "Hello 
world"-c-code compiled successfully to JavaScript.
2. I've downloaded/extracted http://www.ijg.org/files/jpegsrc.v9a.tar.gz. 
I've made sure that I can build the included programs like djpeg or cjpeg.
3. I've made some modifications to example.c (mainly adding a 
main-function) and created a makefile for compiling it with gcc.
4. I've made sure I can successfully run the natively compiled "example".
5. I called emcc for example.c with HTML-output, getting the following:
      warning: unresolved symbol: jpeg_read_header
      warning: unresolved symbol: jpeg_CreateDecompress
      warning: unresolved symbol: jpeg_start_decompress
      warning: unresolved symbol: jpeg_stdio_src
      warning: unresolved symbol: jpeg_std_error
      warning: unresolved symbol: jpeg_destroy_decompress
      warning: unresolved symbol: jpeg_finish_decompress
      warning: unresolved symbol: jpeg_read_scanlines
6. I've opened the generated HTML-output in a Firefox instance, but get 
      file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.data
      uncaught exception: abort(-1) at 
jsStackTrace@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:1316:13
      
stackTrace@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:1333:22
      
abort@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10939:44
      
_jpeg_std_error@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:6541:59
      
_jpeg_std_error__wrapper@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10637:59
      
dynCall_ii@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10605:10
      
invoke_ii@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:6663:12
      
_read_JPEG_file@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:6902:11
      
_main@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:7091:8
      
asm._main@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10676:8
      
callMain@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10805:15
      
doRun@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10863:42
      
run/<@file:///home/kopiske/emscripten/jpeg-components/jpeg-9a/example.js:10874:7

      "pre-main prep time: 241 ms" example.html:1245
      Module.printErr() example.html:1245
      doRun() example.js:10858
      run/<() example.js:10874

      "missing function: jpeg_std_error" example.html:1245
      Module.printErr() example.html:1245
      _jpeg_std_error() example.js:6541
      _jpeg_std_error__wrapper() example.js:10637
      dynCall_ii() example.js:10605
      invoke_ii() example.js:6663
      _read_JPEG_file() example.js:6902
      _main() example.js:7091
      asm._main() example.js:10676
      callMain() example.js:10805
      doRun() example.js:10863
      run/<()


I haven't provided the modified example.c, since I get the same warnings 
mentioned in step 5 when I try to compile the unmodified "djpeg" with emcc.

When I provide -s INCLUDE_FULL_LIBRARY=1 to emcc, the warnings disappear, 
but the error in 6 still remains. I have no idea why the used functions are 
not included.

Any help with this is highly appreciated! (As you might have noticed, my 
knowledge of C is rudimentary to non-existent ;-))

Best regards,
Björn

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