Hello everyone,
I am trying to understand the C program of SFListen tool of tinyos - 1.x,
which reads the packets from SerialForwarder and dumps them on the cygwin
window.
Here is the concerned code:
----------------------------------------------------
*int init_sf_source(int fd)
/* Effects: Checks that fd is following the serial forwarder protocol
Sends 'platform' for protocol version '!', and sets 'platform' to
the received platform value.
Modifies: platform
Returns: 0 if it is, -1 otherwise
*/
{
char check[2], us[2];
int version;
unsigned char nonce[4];
/* Indicate version and check if serial forwarder on the other end */
us[0] = 'T'; us[1] = '!';
if (safewrite(fd, us, 2) != 2 ||
saferead(fd, check, 2) != 2 ||
check[0] != 'T' || check[1] < ' ')
return -1;
version = check[1];
if (us[1] < version)
version = us[1];
switch (version)
{
case ' ': break;
case '!':
nonce[0] = platform;
nonce[1] = platform >> 8;
nonce[2] = platform >> 16;
nonce[3] = platform >> 24;
if (safewrite(fd, nonce, 4) != 4)
return -1;
if (saferead(fd, nonce, 4) != 4)
return -1;
//Unlike the more general SFProtocol.java this piece of code always
knows what platform it is connected to; just drop the preferred platform
from the client
//platform = nonce[0] | nonce[1] << 8 | nonce[2] << 16 | nonce[3] << 24;
break;
}
return 0;
}*
-----------------------------------------
I have understood whole code except this part:
* case '!':
nonce[0] = platform;
nonce[1] = platform >> 8;
nonce[2] = platform >> 16;
nonce[3] = platform >> 24;
if (safewrite(fd, nonce, 4) != 4)
return -1;
if (saferead(fd, nonce, 4) != 4)
return -1;
*I am not able to understand which platform variable we are referring here.
I opened platform.h file and found that:
#define AVRMOTE 1
#define TELOS 2
#define MICAZ 3
#define EYES 4
#define TINYNODE 5
Are we referring to these values only? I am not very sure about this.
Could anyone please give me more insight into this. Please try to help me in
understanding this part of the code. Its little bit urgent. I am trying to
right my own application similar to SFListen.
Thank you so much.
Vishal*
*
--
Vishal Pal
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