VHDL Code-Multiplication

Question

I am new to this site. I have to work on a project which needs vhdl coding and I am new to it too.

i just need to multiply two elements . so i do that by entering a*b. but i get this error " found 0 defntiions of operator "*" " .i have included these libraries

use IEEE.STD_LOGIC_1164.all;

use ieee.numeric_std.all;

use ieee.std_logic_arith.all;

i have tried giving it this way.. result <= std_logic_vector(a*b) seeing one of the forums. then I get the following error.

near std_logic_vector " type conversion expression type cannot be determined uniquely"

a and b can be complex numbers

Please help me. How could just multiplication of two elements have so many complications in VHDL ? :(

altera_forum · Answer

You need to use the signed/unsigned types that are in the numeric_std package. And don't use std_logic_arith.  resut &lt;= std_logic_vector(unsigned(a) * unsigned(b));

altera_forum · Answer

thanks for your reply. Is std_arth not for arithmetic operations??

and i got the previous problem solved.can you help me in few more doubts?

1.Will signed and unsigned include complex numbers??

2.how to define a data type of matrix in vhdl and how to access the elements?

My knowledge on vhdl is limited. Please do help :)

altera_forum · Answer

std_logic_arith is a non-standard VHDL package, and it conflicts with numeric_std, so do not use it.

1. signed an unsigned are just integers - but you can use them to represent fixed point. for complex numbers just store separate parts, or create a new record type that contains both. Thats what the type system is there for.

2. to create an array:

type my_array_t is array(0 to n) of integer; --of course you can use any type in the array

altera_forum · Answer

Thank you very much people for your timely response. Will come to you if i get struck somewhere again.

altera_forum · Answer

I have defined an array as

type array_name :array(natural range <>) of real;

variable arr : array_name(0 to 10000);

Supposing that i have given all values to the arr, How do i access only first 50 elements of it.

will arr(0 to 50) work??

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VHDL Code-Multiplication

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