Example of passing a static array of bytes from SystemVerilog to C via DPI

SystemVerilog
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1

Could somebody post an example for reference? I am not able to find any from the forum.
Thanks.

2

In reply to dnguyen82us:

Can you show the SystemVerilog code which will be calling the DPI? And what does the C function look like which will be processing the data?

3

In reply to cgales:


module SV_monitor;
   byte packet_data [2048];
   task pass_2_C ();
      // passing packet_data array to a C function
   endtask
endmdule

// I think the C function would have parameters length, handle and then print the array
4

In reply to dnguyen82us:

Here is some code to get started. Refer to the LRM for all the DPI related functions available for array information. Also, most simulators will generate DPI headers for C/C++ code, so you can ensure that your function prototypes match.

sv_monitor.sv


import "DPI-C" function void dpi_monitor(byte data[]);

module sv_monitor();
  byte packet_data[2048];

  initial begin
      dpi_monitor(packet_data);
  end
endmodule

header.h

#ifndef INCLUDED_HEADER
#define INCLUDED_HEADER

#ifdef __cplusplus
#define DPI_LINK_DECL  extern "C" 
#else
#define DPI_LINK_DECL 
#endif

#include "svdpi.h"

DPI_LINK_DECL DPI_DLLESPEC
void
dpi_monitor(
    const svOpenArrayHandle data);

#endif

dpi.c

#include <stdio.h>
#include "header.h"

void dpi_monitor(const svOpenArrayHandle data) {
    int size;
    int dimensions;

    dimensions = svDimensions(data);

    printf("Data array has %d dimensions\n", dimensions);

    size = svSize(data, 1);
    
    printf("Data array has %d elements\n", size);
}
5

In reply to cgales:

How do you get the values of data [idx] in C domain? Thanks.

6

In reply to dnguyen82us:

As I stated in my previous response, you need to refer to the LRM on how to access the array data. Section H.12 provides all the information required on accessing Open arrays.

7

In reply to cgales:

I implemented the dpi_monitor as the following:


void dpi_monitor (svOpenArrayHandle data) {
    int idx, size;
    unsigned char byte;

    size = svSize (data, 1);

    for (idx = 0; idx < size; idx++) {
        byte = *(unsigned char *) svGetArrElemPtr1 (data, idx); // Extract array elements in C domain
        printf ("data [%0d] = %02x ", idx, byte);
    }
}