Om. escribió:
On 7/27/06, Martin Röhricht <ml@xxxxxxxxxxx> wrote:
Am Donnerstag, den 27.07.2006, 23:14 +0530 schrieb Gaurav Dhiman:
> Can someone point me the use of these funtions in kernel, and why we
> use them, does not the compiler handle the machine specific endian
> issues ??
Consider using networking packets. To interpret them in the correct way
they need to be specified for one order. The Bluetooth specification for
example specifies it's packets in little endian order. If you didn't use
Another example is PCI specification. All the data put onto the pci
buses should be little endian. Assuming we are running on PPC, every
read/write to pci must be converted back and forth.
You can find the examples in almost all pci device drivers
Regards,
Om.
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I think that the most easy way of understanding the endianess problem is
something like this... Suppose a system where an int in a 16 bit type,
and byte is a 8 bit type...
int a = 300; //(that is 1*256 + 44).
byte b = *((byte*)(&a));
So... If I get the contents of the first byte of the address in which a
is stored... Am I getting a 1 or a 44...?
The problem arises when we store the data in a format (structures for
example), and try to read them in another format... usually each byte at
a time.
Miguel Ángel
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