Read a binary file with many type of data (Int64-int​32-int64-i​nt32....)

Hi,

i have a binary file generated by a DAQ equipment

This file contains header + data

this is the structure of the Header

64 bit 32 bit 64 bit 32 bit 32 bit 32 bit

The data is structured : Ch1 Ch2 Ch3 Ch4 Ch5 Ch6 Ch7 Ch8 Ch1 Ch2 Ch3 Ch4 Ch5 Ch6 Ch7 Ch8 Ch1 Ch2 Ch3 Ch4 Ch5 Ch6 Ch7 Ch8 ......

The type of data is int32

sampling rate depends of the configuration in my case is : 4Khz.

any idea ?

i have to read it bit by bit ?

Answer 1

[Walter Roberson]

fid = fopen('filename');

H1 = fread(fid, 1, '*uint64');
H2 = fread(fid, 1, '*uint32');
H3 = fread(fid, 1, '*uint64');
H4 = fread(fid, 3, '*uint32');

data = fread(fid, [8 inf], 'int32') .';

fclose(fid);

You might need to adjust the datatypes of the header items.

You might need to use swapbytes

[Steven Lord]

Or you could import all the data as a specific integer type and use typecast to turn some subset of that data into a different integer type.

x = randi([intmin('int32') intmax('int32')], 1, 2, 'int32')

x = 1×2

-1970168189 189586747

class(x)

ans = 'int32'

y = typecast(x, 'int64')

y = int64 814268880444825219

z = typecast(flip(x), 'int64')

z = int64 -8461807939184960197

w = typecast(y, 'int32')

w = 1×2

-1970168189 189586747

class(w)

ans = 'int32'

isequal(x, w)

ans = logical
   1

Looking at the bit patterns:

format hex
x

x = 1×2

8a919e83 0b4cdd3b

y

y = int64
   0b4cdd3b8a919e83

z

z = int64
   8a919e830b4cdd3b

[Walter Roberson]

fid = fopen('filename', 'r', 'ieee-be');  %big endian

header.firstDate_s = fread(fid, 1, '*uint64');
header.firstDate_ns = fread(fid, 1, '*int32');
header.secondDate_s = fread(fid, 1, '*uint64');
header.secondDate_ns = fread(fid, 1, '*int32');
header.maskVoi = fread(fid, 1, '*int32');
header.size = fread(fid, 1, '*int32');

data = fread(fid, [8 inf], 'int32') .';

fclose(fid);

[StSab]

thanks !!

it works !

'ieee-be' big endian