MODULUS operator

[priya]

hi all
i m using integer data type in VHDL .i have to perform modulo
operation.
but the problem i m facing is that the operand must be a constant
like
A<= (A+1) MOD X
where X is not a constant.
during synthesis i m facing this problem
plz help out soon
one more thing
in case of for loop
for i in 0 to N loop
end loop
again N is sppsed to be fixed

best regards
priya

 

[Ved]

You can use Fixed package availabe at www.eda.org/fphdl , written by
David Bishop.
Its very easy to use and synthesise well with synplify-pro. I havn't
used it on ISE or QUARTUS.

Regards
Ved

priya wrote:

hi all
i m using integer data type in VHDL .i have to perform modulo
operation.
but the problem i m facing is that the operand must be a constant
like
A<= (A+1) MOD X
where X is not a constant.
during synthesis i m facing this problem
plz help out soon
one more thing
in case of for loop
for i in 0 to N loop
end loop
again N is sppsed to be fixed

best regards
priya

 

[Andy]

Modulo by a non-integer power of two is not supported by most synthesis
tools.

You could say:

if a + 1 > x then
a <= a + 1 - x;
else
a <= a + 1;
end if;

Which will synthesize for any value of x.

Andy

priya wrote:

hi all
i m using integer data type in VHDL .i have to perform modulo
operation.
but the problem i m facing is that the operand must be a constant
like
A<= (A+1) MOD X
where X is not a constant.
during synthesis i m facing this problem
plz help out soon
one more thing
in case of for loop
for i in 0 to N loop
end loop
again N is sppsed to be fixed

best regards
priya

 

[priya]

hi
i m using Xilinx ISE 7.01.04i
best regards
priya
Ved wrote:

You can use Fixed package availabe at www.eda.org/fphdl , written by
David Bishop.
Its very easy to use and synthesise well with synplify-pro. I havn't
used it on ISE or QUARTUS.

Regards
Ved

priya wrote:
hi all
i m using integer data type in VHDL .i have to perform modulo
operation.
but the problem i m facing is that the operand must be a constant
like
A<= (A+1) MOD X
where X is not a constant.
during synthesis i m facing this problem
plz help out soon
one more thing
in case of for loop
for i in 0 to N loop
end loop
again N is sppsed to be fixed

best regards
priya