Passing struct as an argument

Here's a complete example of operating on a SystemVerilog packed struct from the DPI (C) side. It's important to look at the svdpi.h file in the /tools/inca/include directory to understand this.

-----file top.v-------
module top ();

// import functions do a call from SV to C
import "DPI-C" context addone_c= function int addone_sv(input int x);
import "DPI-C" context function void show_vec_inC(input bit [31:0] some_vec);
import "DPI-C" context function void show_logic_inC(input logic [31:0] some_vec);

typedef struct packed {
int a;
bit [9:0] b;
bit [5:0] c;
} mydata_struct_s;
import "DPI-C" context function void pass_struct(inout mydata_struct_s t );

bit [31:0] some_vec = 32'h12345678;
logic [31:0] some_logic = 32'h8765X32Z;

mydata_struct_s mydata_struct_i;

initial
begin
$display("Gimme_Int %d",addone_sv(5));
show_vec_inC(some_vec); // pass reference per SV spec
show_logic_inC(some_logic); // pass reference per SV spec

// stuff the structure with data
mydata_struct_i.a = 9;
mydata_struct_i.b = 10'b10_1011_0110;
mydata_struct_i.c = 6'b11_0101;

pass_struct(mydata_struct_i); // pass reference to packed struct

$display("Verilog a %d", mydata_struct_i.a);
$display("Verilog b %h", mydata_struct_i.b);
$display("Verilog c %h", mydata_struct_i.c); // in this example the DPI inverts this data

end

endmodule

-----file: main_task.c-----
#include
#include

// Copyright Cadence Design Systems, Todd Mackett 2007

// This is an example of manipulating packed data structure in SystemVerilog
// Use /tools/inca/include/svdpi.h as a reference

int addone_c(int x) {
return x +1;
}

void show_vec_inC(svBitVecVal* x) {
printf("show_vec_inC\n");
printf("a= %x\n", *x);
}

// svLogicVecVal can have 0,1,X,Z
void show_logic_inC(svLogicVecVal* x) {
printf("show_Logic_inC\n");
printf("a= %x\n", *x);
printf("aval %x\n", x->a);
printf("bval %x\n", x->b);

}


void pass_struct( svBitVecVal* x) { // NOT const so that this can be modified
// can use x[0] to reference raw array
// printf("Struct = %x, %x\n", x[0], x[1] );
svBitVecVal aa; // define a local svBitVecVal
// extract field a of SV "struct packed {...} mydata_struct_s

svGetPartselBit(&aa , x, 16, 32);
printf("mydata_struct_s.a: %x \n", aa);

svGetPartselBit(&aa , x, 6, 10);
printf("mydata_struct_s.b: %x \n", aa);
// everything above here works

svGetPartselBit(&aa , x, 0, 6);
printf("mydata_struct_s.c: %x \n", aa);

// svPutBitselBit(aa, 0, sv_0);
printf("AA %x \n", aa);
// do some manipulation on the local svBitVecVal
aa = ~aa; // invert the bits (some generic bit manipulation routine)

// can do something like this too: just set the value of Verilog Structure
// aa = 13;
printf("AA %x \n", aa);

svPutPartselBit(x, aa, 0, 6); // this will modify the Verilog structure

}
------file: RUN_NC------(script)------------
rm -r INCA_libs
rm *.so
rm *.log
rm *.h

# Create .h file for Exported tasks/functions only
# (imported function do NOT need .h file):
ncverilog +sv top.v +ncdpiheader+dpi.h +elaborate +ncelabargs+-messages

# ncvlog -sv top.v -mess
# ncelab top -sv -dpiheader dpi.h -mess

gcc -fPIC -shared -o main_task.so main_task.c -I/`ncroot`/tools/inca/include

ncverilog +sv top.v +sv_lib=main_task.so +ncsimargs+"-sv_root ./"

-----screen results, with some comments inserted-----------

ncsim> run
Gimme_Int 6
show_vec_inC
a= 12345678
show_Logic_inC
a= 8765f320
aval 8765f320
bval f00f
mydata_struct_s.a: 9
mydata_struct_s.b: 2b6
mydata_struct_s.c: 35
AA 35
AA ffffffca
Verilog a 9
Verilog b 2b6
Verilog c 0a <--- notice the DPI inverted the bits in this case
ncsim: *W,RNQUIE: Simulation is complete.
ncsim> exit

Here's a complete example of operating on a SystemVerilog packed struct from the DPI (C) side. It's important to look at the svdpi.h file in the /tools/inca/include directory to understand this.

-----file top.v-------
module top ();

// import functions do a call from SV to C
import "DPI-C" context addone_c= function int addone_sv(input int x);
import "DPI-C" context function void show_vec_inC(input bit [31:0] some_vec);
import "DPI-C" context function void show_logic_inC(input logic [31:0] some_vec);

typedef struct packed {
int a;
bit [9:0] b;
bit [5:0] c;
} mydata_struct_s;
import "DPI-C" context function void pass_struct(inout mydata_struct_s t );

bit [31:0] some_vec = 32'h12345678;
logic [31:0] some_logic = 32'h8765X32Z;

mydata_struct_s mydata_struct_i;

initial
begin
$display("Gimme_Int %d",addone_sv(5));
show_vec_inC(some_vec); // pass reference per SV spec
show_logic_inC(some_logic); // pass reference per SV spec

// stuff the structure with data
mydata_struct_i.a = 9;
mydata_struct_i.b = 10'b10_1011_0110;
mydata_struct_i.c = 6'b11_0101;

pass_struct(mydata_struct_i); // pass reference to packed struct

$display("Verilog a %d", mydata_struct_i.a);
$display("Verilog b %h", mydata_struct_i.b);
$display("Verilog c %h", mydata_struct_i.c); // in this example the DPI inverts this data

end

endmodule

-----file: main_task.c-----
#include
#include

// Copyright Cadence Design Systems, Todd Mackett 2007

// This is an example of manipulating packed data structure in SystemVerilog
// Use /tools/inca/include/svdpi.h as a reference

int addone_c(int x) {
return x +1;
}

void show_vec_inC(svBitVecVal* x) {
printf("show_vec_inC\n");
printf("a= %x\n", *x);
}

// svLogicVecVal can have 0,1,X,Z
void show_logic_inC(svLogicVecVal* x) {
printf("show_Logic_inC\n");
printf("a= %x\n", *x);
printf("aval %x\n", x->a);
printf("bval %x\n", x->b);

}


void pass_struct( svBitVecVal* x) { // NOT const so that this can be modified
// can use x[0] to reference raw array
// printf("Struct = %x, %x\n", x[0], x[1] );
svBitVecVal aa; // define a local svBitVecVal
// extract field a of SV "struct packed {...} mydata_struct_s

svGetPartselBit(&aa , x, 16, 32);
printf("mydata_struct_s.a: %x \n", aa);

svGetPartselBit(&aa , x, 6, 10);
printf("mydata_struct_s.b: %x \n", aa);
// everything above here works

svGetPartselBit(&aa , x, 0, 6);
printf("mydata_struct_s.c: %x \n", aa);

// svPutBitselBit(aa, 0, sv_0);
printf("AA %x \n", aa);
// do some manipulation on the local svBitVecVal
aa = ~aa; // invert the bits (some generic bit manipulation routine)

// can do something like this too: just set the value of Verilog Structure
// aa = 13;
printf("AA %x \n", aa);

svPutPartselBit(x, aa, 0, 6); // this will modify the Verilog structure

}
------file: RUN_NC------(script)------------
rm -r INCA_libs
rm *.so
rm *.log
rm *.h

# Create .h file for Exported tasks/functions only
# (imported function do NOT need .h file):
ncverilog +sv top.v +ncdpiheader+dpi.h +elaborate +ncelabargs+-messages

# ncvlog -sv top.v -mess
# ncelab top -sv -dpiheader dpi.h -mess

gcc -fPIC -shared -o main_task.so main_task.c -I/`ncroot`/tools/inca/include

ncverilog +sv top.v +sv_lib=main_task.so +ncsimargs+"-sv_root ./"

-----screen results, with some comments inserted-----------

ncsim> run
Gimme_Int 6
show_vec_inC
a= 12345678
show_Logic_inC
a= 8765f320
aval 8765f320
bval f00f
mydata_struct_s.a: 9
mydata_struct_s.b: 2b6
mydata_struct_s.c: 35
AA 35
AA ffffffca
Verilog a 9
Verilog b 2b6
Verilog c 0a <--- notice the DPI inverted the bits in this case
ncsim: *W,RNQUIE: Simulation is complete.
ncsim> exit