fwrite int64 not supported

Question

Andrea Bettati 2019-6-28

回答： Guillaume 2019-6-28

Hi to you all,

I'm using matlab to exchange data with a cortex M4 board.

In my embedded c code I enabled the usb vcom and I am able to write and read using

fwrite()
fread()

Everything is fine if I use 'int32' as precision, but 'int64' is not supported.

Unfortunately I need to send to my board some int64 parameters and I wonder which is the best way of doind this.

Any hints?

Answer 1

Guillaume 2019-6-28

Well, a 64 bit integer can be easily split into two 32-bit halves. You'd need to know the endianess of your environment but it's going to be either:

%input: 
% val64: a uint64 integer scalar
val64as32 = typecast(val64, 'uint32');
fwrite(something, val64as32, 'uint32')

or

%input: 
% val64: a uint64 integer scalar
val64as32 = fliplr(typecast(val64, 'uint32'));
fwrite(something, val64as32, 'uint32')