ssize_t e_read

[gordon]

[CocoaGeek]

Hello,

Couple of things:

- If you are only reading a single float, buf0 doesn't need to be a pointer but just a float variable
- It looks like you have a "ssize_t *" before your call to e_read. That's incorrect. You should be assigning the return value of e_read to a variable, ignoring it, or directly comparing the value to sizeof(float).

Hope this help.

[gordon]

I have tried removing ssize_t and declaring buff just as a pointer. But now it shows dev is undeclared. I tried initializing it in the device program as (e_epiphany_t dev;) for which i need to use <e-hal.h> but then it terminates when i include the library.

[nickoppen]

Looking at your code the second parameter of e_read is not the epiphany device. Look in the epiphany_sdk_ref (page 95) for an explanation of the parameters.

Yes you have declared buf as a pointer but you have not allocated any memory for the actual value. If it is a local variable declare it float buf; and then if you need it as a typeless pointer you need to de-reference it and then type cast it (void *)&buf;.

This is what C programming is like. You just have to scratch your head until you figure it out.

[gordon]

I have used ssize_t e_read which is mentioned under the data transfer functions part of the manual (Page no.131)

and its synstax goes like this:

ssize_t e_read(void *dev, unsigned row, unsigned col, off_t from_addr, void *buf, size_t size)

When i declare this statement in the device code, it gives me dev undeclared, but i cant use e-hal.h library in my device code. But which i declare the same statement in host code I'm getting a segmentation error.

[sebraa]

You are only supposed to use e_read() in the host code. The device code doesn't use it.

[GreggChandler]

Although I don't use e_read() on the Epiphany cores, (I use memory pointers and move functions,) the eSDK does document the use of e_read() and e_write() on the Epiphany core (p. 95 of the Epiphany_sdk_ref, section 13.15.2). One must be careful, as the use documented on the host (p. 131, section 14.4.2) uses slightly different parameters. In particular, compare parameter pay attention to parameter 1. In summary, there is an e-lib version and a e-hal version. The function is declared in the appropriate header (.h) file.