problems with behavioral compiler

[YiYin Wang]

Dear All,
I have used the Behavioral Compiler to synthesize a FIR filter.
I want to constrain a loop. But when I use " find " command to find the
loop, it always reports error and get no results.

the command I used is
"bc_shell> find cell -hierarchy *filter_loop*"
and the feedback is :
"Error: Can't find object '*filter_loop*'.(UID-109)
{}"

How could I solve this problem?

Thanks a lot.
Best Regards

Yiyin Wang
My code is below:

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.std_logic_arith.ALL;
USE ieee.std_logic_signed.ALL;

ENTITY fir_filter2 IS
PORT (
clk : IN std_logic;
rst : IN std_logic;
load : IN std_logic;
data_in : IN signed( 11 DOWNTO 0 );
coeff_addr : IN unsigned( 3 DOWNTO 0 );
start : IN std_logic;
data_out : OUT signed( 11 DOWNTO 0 )
);
END fir_filter2;

ARCHITECTURE behavioral OF fir_filter2 IS
BEGIN

main_proc: PROCESS

SUBTYPE coeff_element IS signed( 11 DOWNTO 0 );
TYPE coeff_type IS ARRAY ( integer RANGE <> ) OF
coeff_element;
VARIABLE coeff : coeff_type( 0 TO 14 );

SUBTYPE history_element IS signed( 11 DOWNTO 0 );
TYPE history_type IS ARRAY ( integer RANGE <> ) OF
history_element;
VARIABLE history : history_type( 0 TO 14 );

VARIABLE sum : signed( 23 DOWNTO 0 );
ATTRIBUTE unroll_new_instance : boolean;
ATTRIBUTE unroll_new_instance OF sum : VARIABLE IS true;

BEGIN

reset_loop: LOOP

--
-- reset the data output
--

data_out <= ( OTHERS => '0' );

WAIT UNTIL clk'EVENT AND ( clk = '1' );
EXIT reset_loop WHEN ( rst = '1' );


--
-- Initialize all coefficients to zero
--
FOR i IN 0 TO 14 LOOP
coeff( i ) := ( OTHERS => '0' );
END LOOP;

--
-- Initialize history memory to zero
--
FOR i IN 0 TO 14 LOOP
history( i ) := ( OTHERS => '0' );
END LOOP;

main_loop: LOOP

config_loop: LOOP

--
-- Wait until next clock cycle to check for
-- load or filter signals.
--
WAIT UNTIL clk'EVENT AND ( clk = '1' );
EXIT reset_loop WHEN ( rst = '1' );

IF ( start = '1' ) THEN
EXIT config_loop;
END IF;

IF ( load = '1' ) THEN
coeff( conv_integer( '0' & coeff_addr ) ) :=
data_in;
END IF;

END LOOP config_loop;

--
-- Main filter loop
--
filter_loop: LOOP -- pragma n_unroll 3
-- pragma pipeline_init_interval 1

WAIT UNTIL clk'EVENT AND ( clk = '1' );
EXIT reset_loop WHEN ( rst = '1' );

history( 0 ) := signed( data_in );

sum := ( ( ( history( 0 ) * coeff( 0 ) +
history( 1 ) * coeff( 1 ) ) +
( history( 2 ) * coeff( 2 ) +
history( 3 ) * coeff( 3 ) ) ) +
( ( history( 4 ) * coeff( 4 ) +
history( 5 ) * coeff( 5 ) ) +
( history( 6 ) * coeff( 6 ) +
history( 7 ) * coeff( 7 ) ) ) ) +
( ( ( history( 8 ) * coeff( 8 ) +
history( 9 ) * coeff( 9 ) ) +
( history( 10 ) * coeff( 10 ) +
history( 11 ) * coeff( 11 ) ) ) +
( ( history( 12 ) * coeff( 12 ) +
history( 13 ) * coeff( 13 ) ) +
history( 14 ) * coeff( 14 ) ) );

data_out <= sum( 23 DOWNTO 12 );

FOR i IN 14 DOWNTO 1 LOOP
history( i ) := history( i - 1 );
END LOOP;

END LOOP filter_loop;

END LOOP main_loop;

END LOOP reset_loop;

END PROCESS;

END behavioral;

 

[mike_treseler]

Did this process simulate as you expected?
Consider recoding this in a single synchronous
process without all the loops.

-- Mike Treseler