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Altera_Forum's avatar
Altera_Forum
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10 years ago

Assign all zeroes to unsigned

Hi, I want to assign all zeroes to an unsigned signal. I've been using ( others => '0' ) for STD_LOGIC_VECTOR signals, but when i attempt to do the same for unsigned, i get an error:

Error (10500): VHDL syntax error at top.vhd(222) near text "others"; expecting "(", or an identifier ("others" is a reserved keyword), or unary operator

Does this only work at the declaration of the signal? Can I use it within my process on reset for example? if not, is there another easy way to set a signal to all zeroes? ( i am trying to avoid typing it all out since I plan to change the size of these signals between subsequent runs. )

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    Unsigned is a base 10 nuber without a sign. So assigning 0 should work.

    unsigned_sig <= 0;
  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    --- Quote Start ---

    Unsigned is a base 10 nuber without a sign. So assigning 0 should work.

    unsigned_sig <= 0;

    --- Quote End ---

    You can't do that because 0 is an integer. Also note that unsigned is binary, not base 10.

    You need to convert to an unsigned from an integer.

    Op <= to_unsigned(0, op'length);

    This should also work.

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

    The ops problem sounds like a syntax error. Why not post the actual code?
  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    unsigned type accepts (others => '0');

    it also accepts comparing with integer type but not assigning to integer type
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    --- Quote Start ---

    You can't do that because 0 is an integer. Also note that unsigned is binary, not base 10.

    You need to convert to an unsigned from an integer.

    Op <= to_unsigned(0, op'length);

    This should also work.

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

    The ops problem sounds like a syntax error. Why not post the actual code?

    --- Quote End ---

    Hi, I have no idea what the problem was but i reverted my code to a previous save and made my changes one by one and it worked! i wish i knew what caused the problem in the first place, but i cant even seem to reproduce it now.