slicing /inverting vectors?

[Guest_imported]

I've got a bus 16 bits long and it looks like that "1111 0000 1010 0011" I would lith to take the output like that i "0011
1010 0000 1111" (as you look at it)

from the left to the rigth

the inout is 16 and the output is 4 bits long
i have done the example below but is not working.:
frame_out_s <= tx_dat_s (3 downto 0 ) ;
tx_dat_s(15 downto 4) <= tx_dat_s (11 downto 0);



please help me...
regards
alex

 

[chinna24]

hi!
in u r code u r not storing the present value in the intermediate variable so u will loose some bits before reversing the bus.

so first store u r bus bits in some temporary variable say
temp(15 down to 0) <= tx_dat_s(15 downto 4)
then
from the temp varible reverse the bits to tx_dat_s(15 downto 4)

tx_dat_s(15 downto 4) <= temp(11 downto 0);

give a try and let me know whether it works or not
Bye
Praveen