Nest if statement in case statement

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Hi,

Is it customary and synthesizable to use nested 'case' statement inside the 'if' statement?

Tnx

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No it is not , but it dosent make any sense why would anyone use "case" inside a "if" when you can use elsif multiple times .

for example:

Interfacing_ADC_DAC: PROCESS(sys_clk, reset_n)

BEGIN

IF reset_n = '0' THEN

ADC_data_A <= (others=>'0');

ADC_data_B <= (others=>'0');

--

DA <= (others=>'0');

DB <= (others=>'0');

--

LEDG(1 downto 0) <= (others=>'0');

-- 1st Condition -------------------

ELSIF SW(4 downto 2) = "011" THEN

LEDR(2 downto 0) <= "001";

ADC_data_A <= ADA_D;

ADC_data_B <= ADB_D;

----------------

-- DAC is connected to an Up-Counter

DA <= Count;

DB <= not(Count);

-- 2nd Condition -------------------

ELSIF SW(4 downto 2) = "010" THEN

LEDR(2 downto 0) <= "010";

-- ADC output is connected directly to DAC

DA <= ADA_D;

DB <= ADB_D;

-- 3rd Condition -------------------

ELSIF SW(4 downto 2) = "001" THEN

LEDR(2 downto 0) <= "100";

-- DAC is connected to a NOC output

DA <= nco_sin_out + OFF_set;

DB <= nco_sin_out + OFF_set;

-- 4th Condition ----------------<< FIR Filter

ELSIF SW(4 downto 2) = "101" THEN

LEDR(2 downto 0) <= "100";

-- ADC is connected to FIR Filetr

ast_sink_data <= ADA_D;

ADC_data_B <= ADB_D;

-- DAC is connected to a NOC output

DA <= ast_source_data;

DB <= not(Count);

------------

END IF;

END PROCESS;

Tnx for quick response.

The "No it is not" answer refers to customary or synthesizable or both of them?

Tnx

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Tnx for quick response.

The "No it is not" answer refers to customary or synthesizable or both of them?

Tnx

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unfortunately I disgree with the "no..." from fpga_guru011.

The main differences are to do with priority issues. the case statement is equivalent to multiple parallel ifs.

Most of everyday code is made up of " if" or "case" inside each other.

if rising_edge(clk) then

if enable = '1' then

case ....

when ....

if...

end if;

end case;

end if;

end if;

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Tnx for quick response.

The "No it is not" answer refers to customary or synthesizable or both of them?

Tnx

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There is no problems using Case inside If or If inside case. It depends what you are doing, and what you expect from the circuit.