Posted on October 14, 2015 at 06:59 Hi
I want to know whether there is penalty on accessing an array from a structure vs accessing by a simple array.
Here is my snippet which i used when I faced the problem
unsigned
char
array_1[10240];
unsigned
char
array_2[10240];
typedef
struct
{
unsgined
char
array_2[10240]
}simple_queue;
typedef
struct
{
simple_queue simple_arr[3]
}simple_stack;
simple_stack struct_var1;
... ....
memcpy
(
char
array_2,
char
array_1, 10240 );
memcpy
(&struct_var1.simple_arr.array_2[0],
char
array_1, 10240 );
....
So I could see that first
memcpy()
took 90microsec, while the second mempy()
took 310microsec. I changed the unsigned char
to int and I could see that each memcpy() took 80 microsec.
So I assume this is related to compiler optimization..
Can someone please explain to me how compiler optimization can lead to this behaviour?
#memory-organization #stm32f429 #compiler
