[Libjpeg-devel-6x] Question about IDCT in decoding

[Zhang P. <zha...@gm...>]

Hi All,

When I was implementing the OpenCL version of JPEG decoding, there are some
question I want to know:
1. Now we completed the OpenCL version of IDCT-is-slow, IDCT-fast(use
short) and IDCT-float. However, I found the following function in
jdictint.c and jindred.c:
    jpeg_idct_1x1
    jpeg_idct_2x2
    jpeg_idct_3x3
    jpeg_idct_4x4
    jpeg_idct_5x5
    jpeg_idct_6x6
    jpeg_idct_7x7
    jpeg_idct_9x9
    jpeg_idct_10x10
    jpeg_idct_11x11
    jpeg_idct_12x12
    jpeg_idct_13x13
    jpeg_idct_14x14
    jpeg_idct_15x15
    jpeg_idct_16x16
I don't know when these function will be used, and I also try to debug
these function, but it isn't been used when my debug.
I didn't implement OpebCL version for them.
Could you give me more info?
2. When I use:
    djpeg -bmp -dct float -outfile out.bmp in.jpg
to decode a image, I found that the results are differnet between jpeg6b
and jpeg8d/jpeg9. The SIMD version is also different from C code. And now
the OCL version is bit-match with 8d/9.
However, if we complile with VS2010, it won't be bit-match, if we use GCC
or VS2012, it's bit-match.
    Is it a bugs?