Hi -
>Dear Chapel devs and users,
>
>
>I already fixed the reverse reading problem. It is only the config of
>the channel reader. Instead of using kind=ionative, I changed kind=iobig
Glad you got it working. FYI, it's also possible to use the formatted
I/O mechanism to read individual integers with different
endianness.
Cheers,
-michael
>:
>module Main{
>
>proc
>main(){
>
>var f =
>open("train-images.idx3-ubyte", iomode.r);
>var r = f.reader(kind=iobig); // <-- I changed here.
>
>var magic:uint(32);
>r.read(magic);
>writef("magic = %xu\n",magic);
>
>var num_images:uint(32);
>r.read(num_images);
>writef("Image Numbers = %xu\n",num_images);
>
>var rows:uint(32);
>r.read(rows);
>writef("rows = %xu\n",rows);
>
>r.close();
>f.close();
>
>
>
>
>}
>}
>
>
>
>
>
>Excuse-me, because I asked silly question.
>
>
>Thank you!
>
>
>Att.
>
>
>Marcos Cleison.
>
>
>2017-05-22 19:25 GMT-03:00 Marcos Cleison Silva Santana
><[email protected]>:
>
>Hi dear Chapel devs and users,
>
>
>I have a newbie question about reading a binary file in Chapel.
>I downloaded the MNIST dataset with idx3 file format.
>
>
>http://yann.lecun.com/exdb/mnist/
>
>
>
>This file is composed of the structure like that:
>
>
>[offset] [type] [value] [description]
>0000 32 bit integer 0x00000803(2051) magic number
>0004 32 bit integer 60000 number of images
>0008 32 bit integer 28 number of rows
>0012 32 bit integer 28 number of columns
>0016 unsigned byte ?? pixel
>0017 unsigned byte ?? pixel
>
>
>
>
>I tried to read the beginner three integers (the magic number, the
>numbers of images and the number of rows). The code used is:
>
>
>module Main{
>
>proc
>main(){
>
>var f =
>open("train-images.idx3-ubyte", iomode.r);
>var r = f.reader(kind=ionative);
>
>var magic:uint(32);
>r.read(magic);
>writef("magic = %xu\n",magic);
>
>var num_images:uint(32);
>r.read(num_images);
>writef("Image Number = %xu\n",num_images);
>
>var rows:uint(32);
>r.read(rows);
>writef("rows = %xu\n",rows);
>
>r.close();
>f.close();
>
>}
>
>}
>
>
>Instead of outputting:
>
>
>magic = 0000803
>Image Numbers = 0000ea60
>rows = 0000001c
>
>
>
>The program is outputting:
>magic = 3080000
>Image Numbers = 60ea0000
>rows = 1c000000
>
>
>
>The value is stored in reverse order.
>
>
>Is this problem related with big-little endian?
>
>
>My computer is x86_64, Intel Core I7, Ubuntu 17, Chapel 1.15.
>
>
>Could you give me some advice?
>
>
>Thank you very much.
>
>
>Att.
>Marcos Cleison
>
>
>
>
>
>
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