Does using register structs affect timing at all (does fitter keep them together?)

Altera_Forum · ‎04-01-2017

Does declaring a register packed structure affect the layout of the registers? (and therefore timing?)

For example,

typedef struct packed {

bit [31:0] ntp_time;

bit [15:0] index;

bit [15:0] value;

bit [15:0] tag;

} _mystruct;

_mystruct table[64];

Does it matter to the fitter that I grouped all these elements together? Or would it be better to separate them instead:

reg [63:0][31:0] ntp_time;

reg [63:0][15:0] index;

reg [63:0][15:0] value;

reg [63:0][15:0] tag;

Using data structures helps me stay organized, but I'm trying to find out if it affects my timing.

Altera_Forum · ‎04-01-2017

How you code it will make no difference. It is the register-register timing that matters - and this wont change when you change the code structure.