memory allocation problems

[robannexs]

Hi all,

Ilets say i have this structure

struct cbw read_command_request;
char buffer[32];

read_command_request.signature=0x43425355;
read_command_request.tag=0x82A36008;
read_command_request.tlength=0x24;
read_command_request.flags=0x80;
read_command_request.cbwlun=0; //'1
read_command_request.clength=0x06;
read_command_request.operation_code=0x12;
read_command_request.lun=0; //'32 '=1
read_command_request.lba=0x00240000;
read_command_request.reserved=0x00;
read_command_request.blocks=0x0000;
read_command_request.controls=0x00;
read_command_request.padding1=0x0000;
read_command_request.padding2=0x0000;
read_command_request.padding3=0x0000;

how do i move my data from read_command_request such that when I do a
&buffer i will get 43 42 53 55 .....00 00 00 00 ?

 

[Bill Pursell]

struct cbw read_command_request;
char buffer[32];

read_command_request.signature=0x43425355;
read_command_request.tag=0x82A36008;

how do i move my data from read_command_request such that when I do a
&buffer i will get 43 42 53 55 .....00 00 00 00 ?

You're best bet is with something like memcpy(), but you may
get 55 53 42 43, depending on the endian-ness of the machine.

 

[Flash Gordon]

struct cbw read_command_request;
char buffer[32];

read_command_request.signature=0x43425355;
read_command_request.tag=0x82A36008;

how do i move my data from read_command_request such that when I do a
&buffer i will get 43 42 53 55 .....00 00 00 00 ?

You're best bet is with something like memcpy(), but you may
get 55 53 42 43, depending on the endian-ness of the machine.

Or you may have padding between the fields especially as it looks from
the way the OP wrote the code as though some of them could be narrower
than an int (0x00 *implies* the programmer thinks it is being assigned
to an 8 bit char type).

So the best bet if you want something that will work correctly is to
copy the data over a field at a time and within each field a byte at a time.