foreach(a.b[i]) begin
foreach(a.b[i][j]) begin
foreach (a.b[i][j].c[k]) begin
d = a.b[i][j].c[k];
end
end
end
a is a class, b is an object of a separate class e in class a, c is a member of class e which is being accessed through b and d is variable being assigned the value present in c.
I am getting a syntax error in first line itself. What is the correct way to loop over the elements of the multi-dimensional array b?
As per section 12.7.3 of the IEEE 1800-2017 LRM, the proper syntax to loop over your multi-dimensional array is:
foreach(a.b[i, j]) begin
foreach (a.b[i][j].c[k]) begin
d = a.b[i][j].c[k];
end
end
Related
I have declared an array
type datastream is array(0 to 10) of signed (5 downto 0);
For simulation, I want to display the array as integer-numbers
So I created
type datastream_int is array(0 to 10) of integer;
and
signal DIN_ARRAY: datastream;
signal DIN_ARRAY_int: datastream_int;
...
DIN_ARRAY_real <= datastream_int(DIN_ARRAY);
But it fails. How to convert it? Dont want to use a for loop
The numeric_std package, that I assume you are using, provides a to_integer function to convert from a single signed value to a single integer object. For an array, you're going to have to use a for loop. Something like this:
for i in DIN_ARRAY'range loop
DIN_ARRAY_int <= to_integer(DIN_ARRAY(i));
end loop;
You could also provide a conversion function (it will also contain a for loop)
function datastream_to_datastream_int( d : datastream ) return datastream_int is
variable r : datastream_int;
begin
for i in d'range loop
r(i) := to_integer(d(i));
end loop;
return r;
end function;
....
--no loop required
DIN_ARRAY_int <= datastream_to_datastream_int(DIN_ARRAY);
So, there will be a for loop somewhere.
Your code fails because you have attempted a type conversion, which is only allowed between similar types - ie. array or record types where the element types match between the two types.
PS. VHDL 2008 provides an integer_vector type in the std.standard library (which is included by default) which may help by allowing you to do this:
signal DIN_ARRAY_int: integer_vector(DIN_ARRAY'range);
If you did decide to keep datastream_int as per your original, you could type convert it to an integer_vector, because the types are similar:
my_iv <= integer_vector(DIN_ARRAY_int);
I have defined a class like
classdef Test
properties
a
b
end
methods
function this = Test(a, b)
this.a = a;
this.b = b;
end
function disp(this)
fprintf('a=%d b=%d\n', this.a, this.b);
end
end
end
But when I want to display a vector of Test, it seems not print each elements of array using the disp function just defined.
>> out = [Test(1,2),Test(3,4)]
out =
a=1 b=3
a=2 b=4
The questions is how to display an array of objects appropriately? Is there a way to overload the disp function and print as the following:
out=
a=1 b=2
a=3 b=4
(In my considering , the output will be same as calling disp function to element of array one by one.. But the output seems like firstly print all the a's value 1 3 and then b's value 2 4.)
You are getting this result because in your statement out = [Test(1,2),Test(3,4)], the variable out becomes an array of the same class Test, but of size [1x2].
If you try out.a in your console, you'll get:
>> out.a
ans =
1
ans =
3
This is a coma separated list of all the values of a in the out array. This is also the first parameter that your custom disp function sees. It then sees another column vector of all the values of b. To understand what the function fprintf is presented with you can also try in your console:
>> [out.a,out.b]
ans =
1 3 2 4
>> [out.a;out.b]
ans =
1 3
2 4
Since fprintf works in column major order, it will consume all the values column wise first. In that case we can see that the last option we tried seems better.
Indeed, if you change your disp function to:
function disp(this)
fprintf('a=%d b=%d\n', [this.a ; this.b]);
end
You get the desired output:
>> out = [Test(1,2),Test(3,4),Test(5,6)]
out =
a=1 b=2
a=3 b=4
a=5 b=6
Whichever size of object array you define. Just keep in mind that if you input an array of Test object they will be considered column wise:
>> out = [ Test(1,2),Test(3,4) ; Test(5,6),Test(7,8) ]
out =
a=1 b=2
a=5 b=6
a=3 b=4
a=7 b=8
Last option, if you want even more granularity over the display of your object array, you can customise it the way you like inside the disp function:
function disp(this)
nElem = numel(this) ;
if nElem==1
fprintf('a=%d b=%d\n', this.a , this.b );
else
for k=1:nElem
fprintf('a=%d b=%d\n', this(k).a , this(k).b);
end
end
end
This produces the same display than before, but since the elements are treated one by one, you could customise even further without having to consider the way arrays are treated by fprintf.
With the syntax you use, you should overload the display function instead of the disp function.
See the (not that simple to read) corresponding page in the documentation.
module rev_array;
int array_in[10]={0,1,2,3,4,5,6,7,8,9};
typedef integer array[9:0];
function array reverse(int array_in[10]);
for(int j=$size(array_in)-1,int i=0;j>=0;j--,i++)
begin
reverse[j]=array_in[i];
end
// working for(integer k=0;k<$size(array_in)-1;k++)
// working $display("reverse[%0d]:%0d", k, reverse[k]);
$display("inside function");
endfunction:reverse
initial
begin
reverse(array_in);
for(integer k=0;k<$size(array_in)-1;k++)
begin
$display("reverse[%0d]:%0d", k, reverse[k]);
end
end
endmodule
Error-[IUS] Illegal use of scope
testbench.sv, 22
rev_array, "rev_array.reverse"
Scope cannot be used in this context
Error-[XMRIBS] Illegal bit select
testbench.sv, 22
Error is found in following cross-module reference, illegal bit select on
the target.
Source info: $display("reverse[%0d]:%0d", k, rev_array.reverse[k]);
I am trying to reverse an array and return it in system verilog function, I am able to see the reversed array inside the function by printing it but
when I try to print it using $display outside the function, I think it is
not being returned properly somehow, in the 4th line from end, getting
errorError-[IUS]
your both issues are related to the line where you use reverse function name as an array within $display.
$display("reverse[%0d]:%0d", k, reverse[k]);
--------------------------------^^^^^^^^^^
this is an illegal syntax causing both messages.
your initial block should look like the following.
initial
begin
array result;
result = reverse(array_in);
//^^^^^^^^^^^^^^^^^^^^^^^^^//
for(integer k=0;k<$size(array_in)-1;k++)
begin
$display("reverse[%0d]:%0d", k, result[k]);
// ^^^^^^ //
end
end
call the function and use returned results for display.
I am a noob at metaprogramming so maybe I am not understanding this. I thought the purpose of the #nloops macro in Base.Cartesian was to make it possible to code an arbitrary number of nested for loops, in circumstances where the dimension is unknown a priori. In the documentation for the module, the following example is given:
#nloops 3 i A begin
s += #nref 3 A i
end
which evaluates to
for i_3 = 1:size(A,3)
for i_2 = 1:size(A,2)
for i_1 = 1:size(A,1)
s += A[i_1,i_2,i_3]
end
end
end
Here, the number 3 is known a priori. For my purposes, however, and for the purposes that I thought nloops was created, the number of nested levels is not known ahead of time. So I would not be able to hard code the integer 3. Even in the documentation, it is stated:
The (basic) syntax of #nloops is as follows:
The first argument must be an integer (not a variable) specifying the number of loops.
...
If I assign an integer value - say the dimension of an array that is passed to a function - to some variable, the nloops macro no longer works:
b = 3
#nloops b i A begin
s += #nref b A i
end
This returns an error:
ERROR: LoadError: MethodError: no method matching _nloops(::Symbol, ::Symbol, ::Symbol, ::Expr)
Closest candidates are:
_nloops(::Int64, ::Symbol, ::Symbol, ::Expr...) at cartesian.jl:43
...
I don't know how to have nloops evaluate the b variable as an integer rather than a symbol. I have looked at the documentation and tried various iterations of eval and other functions and macros but it is either interpreted as a symbol or an Expr. What is the correct, julian way to write this?
See supplying the number of expressions:
julia> A = rand(4, 4, 3) # 3D array (Array{Int, 3})
A generated function is kinda like a macro, in that the resulting expression is not returned, but compiled and executed on invocation/call, it also sees the type (and their type parameters of course) of the arguments, ie:
inside the generated function, A is Array{T, N}, not the value of the array.
so T is Int and N is 3!
Here inside the quoted expression, N is interpolated into the expression, with the syntax $N, which evaluates to 3:
julia> #generated function mysum(A::Array{T,N}) where {T,N}
quote
s = zero(T)
#nloops $N i A begin
s += #nref $N A i
end
s
end
end
mysum (generic function with 1 method)
julia> mysum(A)
23.2791638775186
You could construct the expression and then evaluate it, ie.:
julia> s = 0; n = 3;
julia> _3loops = quote
#nloops $n i A begin
global s += #nref $n A i
end
end
quote
#nloops 3 i A begin
global s += #nref(3, A, i)
end
end
julia> eval(_3loops)
julia> s
23.2791638775186
I have scrubbed manually the LineNumberNodes from the AST for readability (there is also MacroTools.prettify, that does it for you).
Running this example in the REPL needs to declare s as global inside the loop in Julia 1.0.
I want to write a code for postgis in pgAdmin that is based on postgresql. It defines a 3-dimensional array of geometry.
I used this code for it:
DECLARE
G geometry[9][9][9];
BEGIN
for i IN 1..9 LOOP
for j IN 1..9 LOOP
for k IN 1..9 LOOP
G[i][j][k] := [value that I want];
END LOOP;
END LOOP;
END LOOP;
But it returned this error:
"array subscript out of range"
I used this instead:
DECLARE
G geometry[9][9][9];
BEGIN
for i IN array_lower(G, 1)..array_upper(G, 1) LOOP
for j IN array_lower(G, 1)..array_upper(G, 1) LOOP
for k IN array_lower(G, 1)..array_upper(G, 1) LOOP
G[i][j][k] := [value that I want];
END LOOP;
END LOOP;
END LOOP;
I have a different error this time:
"lower bound of FOR loop cannot be null"
I used this in BEGIN Part and solved all the errors:
G[1][1][1] := '01010000200400000000000000000000000000000000000000';
But I think this is not true and doesn't calculate all of the iterations for loops. I think this takes in account only the G[1][1][1]. What should I do now?
In PostgreSQL, simply declaring the array dimensions does not initialize or pre-allocate anything. The array is dynamic in all its dimensions. That differs significantly from the multi-dimensional array implementations found in general programming language like C.
To mimic the logic of these languages, you may first initialize the 9x9x9 array with a statement like this:
G:=array_fill('point(0 0)'::geometry, array[9,9,9]);
Then the rest of the code will just work when refering to G[i][j][k] either as source or destination of assignments.