to_integer can not have such operands in this contex

[A. Kong]

Hi,all,

Here is the part of code which defines the arhitecture of a fetch unit:
=====================================================================
architecture behavioral of fetch is
type type_instruction_array is array(0 to 31) of std_logic_vector(31
downto 0);

begin
process
-- local variable used as a PC internally
variable PC : std_logic_vector(31 downto 0);
variable iaddr : integer := 0;
variable imem : type_instruction_array;
begin
....

====================================================================

In the process i want to convert the PC to an integer

I have tried the following statements:

iaddr := to_integer(PC);
iaddr := to_integer( To_bitvector(PC));
iaddr := to_integer(unsigned(PC));

I got this error messages:

to_integer can
not have such operands in this context.

Well, I am not sure what is wrong here. I was following 4.2.25 of VHDL
Faq1. Is my understanding wrong?

Cheers,
AK

 

[Pieter Hulshoff]

variable PC : std_logic_vector(31 downto 0);
variable iaddr : integer := 0;

If I'm not mistaken, integer in VHDL is defined as a 32 bit signed number.
You cannot take a 32 bit vector, convert it to unsigned, and then place it
within an integer. It won't fit within the range. to_integer uses either
signed or unsigned vectors, so I'd expect the first two examples you gave
to give a different error message, though that will probably depend on your
compiler.

Regards,

Pieter Hulshoff

 

[Moti Cohen]

Hi,all,

Here is the part of code which defines the arhitecture of a fetch unit:
=====================================================================
architecture behavioral of fetch is
type type_instruction_array is array(0 to 31) of std_logic_vector(31
downto 0);

begin
process
-- local variable used as a PC internally
variable PC : std_logic_vector(31 downto 0);
variable iaddr : integer := 0;
variable imem : type_instruction_array;
begin
...

====================================================================

In the process i want to convert the PC to an integer

I have tried the following statements:

iaddr := to_integer(PC);
iaddr := to_integer( To_bitvector(PC));
iaddr := to_integer(unsigned(PC));

I got this error messages:

to_integer can
not have such operands in this context.

Well, I am not sure what is wrong here. I was following 4.2.25 of VHDL
Faq1. Is my understanding wrong?

I'm not sure that the "to_integer" function can be used in order to
convert std_logic_vector to integer. If I remember correctly it can
only be used for signed/unsigned data input.
I usually uses the "conv_integer" conversion from the
STD_LOGIC_UNSIGNED pacakge for peforming such operations
(std_logic_vector -> integer). but if it is a problem you can first
convert the std to unsigned and then to integer.

p.s. - also check that u declared the required ieee pacakge.

I hope that it is helpful...
Moti.

 

[Alan Fitch]

-- local variable used as a PC internally
variable PC : std_logic_vector(31 downto 0);
variable iaddr : integer := 0;

In the process i want to convert the PC to an integer

I have tried the following statements:

iaddr := to_integer(PC);
iaddr := to_integer( To_bitvector(PC));
iaddr := to_integer(unsigned(PC));

The last one
to_integer(unsigned(PC))

looks OK. Have you said

library IEEE;
use IEEE.Numeric_Std.all;

in front of your entity or architecture?

regards

Alan


--
Alan Fitch
Consultant

DOULOS - Developing Design Know-how
VHDL * Verilog * SystemC * Perl * Tcl/Tk * Verification * Project
Services

Doulos Ltd. Church Hatch, 22 Market Place, Ringwood, Hampshire, BH24
1AW, UK
Tel: +44 (0)1425 471223 mail:
(e-mail address removed)
Fax: +44 (0)1425 471573 Web:
http://www.doulos.com

The contents of this message may contain personal views which are not
the
views of Doulos Ltd., unless specifically stated.