How to Pass array from C to SV using SV-DPI?

Question

My objective is to pass an array from C to SV and print the array contents in SV, I have tried the following C program of converting some text file(data_file.txt) (given full source in the link below) to an array and trying to read back the array by using DPI calls in SystemVeilog(SV), in "C" I have passed the array values to my function(mydisplay) which is inside the main func.(please correct me if I am wrong here) also it seems the array values are not read back to the SV environment as I would expect what could be the reason, is there an efficient way to get back the array in SV?

c code:

 void mydisplay(svOpenArrayHandle h) {
  int *a; 
  a =(int*)svGetArrayPtr(h);
  for( i=0;i<idx;i++) {
    io_printf("C: values[%2zu]=0x%02x\n",i,values[i]);
    a[i] = values[i];
    }   
  }   

sv code:

program automatic top; 
   int a[32000];
   import "DPI-C" function void mydisplay(inout int h[]);
   initial begin
      mydisplay(a);
      foreach(a[i]) $display("SV after DPI: a[%0d]=%0d",i,a[i]);
   end 
endprogram

source at EDAplayground

Answer 1

After some trials I've finally found the solution and able to pass the processed text data from C to SV by a small tweak, I just imported a function and called the exported function using already available context method in the SV-DPI as per LRM, also only used the user defined function and removed the main from native "C" lang., this way I was able to read back the values in the array values from C to SV, provided below the code samples, updated code at EDAPlayground

C code:

#include <stdio.h>
#include <stdlib.h> /* for strtol               */
#include <string.h> /* for strchr               */
#include <limits.h> /* for INT_MIN/INT_MAX      */
#include <errno.h>  /* for errno                */
extern int dV(int r);

#define MAXL 50000

unsigned long xstrtoul (char *p, char **ep, int base);

int mydisplay() 
{
    int v[15];
    int sd;
    int d;
    FILE *fp = fopen ("data_file.txt", "r");
    char line[MAXL] = {0};
    unsigned values[MAXL] = {0};
    int base = 16;
    size_t i, idx = 0;

    if (!fp) { /* validate file open */
        fprintf (stderr, "error: file open failen '%s'.\n", fp);
        return 1;
    }

    /* read each line in file (up to MAXL chars per-line) */
    while (fgets (line, MAXL, fp)) {

        char *p = line;
        char *ep = p;
        char digits[3] = {0};
        errno = 0;

        /* convert each string of digits into number */
        while (errno == 0) {

            /* skip any non-digit characters */
            if (!(p = strchr (p, 'x'))) break;
            strncpy (digits, ++p, 2);
            digits[2] = 0;  /* nul-terminate */

            /* convert string to number */
            values[idx++] = (unsigned)xstrtoul (digits, &ep, base);

            if (errno || idx == MAXL) {   /* check for error */
                fprintf (stderr, "warning: MAXL values reached.\n");
                break;
            }
            p += 2;
        }
    }
    if (fp != stdin) fclose (fp);

    /* print results */
    for (i = 0; i < idx; i++)
    {
        printf ("C values[%2zu] : 0x%02x\t", i, values[i]);
        v[d]=values[i];
        sd = dV(v[d]);
     }
return(sd);
}

/** string to unsigned long with error checking */
unsigned long xstrtoul (char *p, char **ep, int base)
{
    errno = 0;

    unsigned long tmp = strtoul (p, ep, base);

    /* Check for various possible errors */
    if ((errno == ERANGE && (tmp == ULONG_MAX)) ||
        (errno != 0 && tmp == 0)) {
        perror ("strtoul");
        exit (EXIT_FAILURE);
    }

    if (*ep == p) {
        fprintf (stderr, "No digits were found\n");
        exit (EXIT_FAILURE);
    }

    return tmp;
}

SV code:

program automatic top();
int res;

import "DPI" context mydisplay= function int mD();
export "DPI" dV =function mydisplay;

function int mydisplay(input int xyz);
  $display ("SV after DPI: %0d\n",xyz);
  return -1;
endfunction

initial begin
  #5 res=mD();
  $display("Finished reading values...\n");
end

endprogram