Open Arrays in DPI - 2024.1 English

Vivado Design Suite User Guide: Logic Simulation (UG900)

Document ID
UG900
Release Date
2024-05-30
Version
2024.1 English

When declaring an import function in SystemVerilog, you might specify formal argument as open arrays. Specifying certain dimension(s) of formal array arguments as blank (open) allows passing actual arguments of different sizes, which facilitates more general C code. On the C side, the open arrays are represented as SVOpenArrayHandle. By passing this handle to the provided functions, you might query the information of the open array. For example, the size of the opened dimension, and access to the actual data.

Declaration

Open arrays might only appear in import function/task declaration in SystemVerilog code. By leaving the dimension(s) open, you must specify an open array and the size of the blank dimension will be determined with respect to the actual argument.

Examples

SystemVerilog function declaration:

import "DPI-C" function int myFunction1(input bit[] v);
import "DPI-C" function void myFunction2(input int v1[], input int v2[], output int 
v3[]);

At C side, the open array(s) might only be accessed by the handle and provided APIs:

int myFunction1(const SVOpenArrayHandle v);
void myFunction2(const SVOpenArrayHandle v1, const SVOpenArrayHandle v2, const 
SVOpenArrayHandle v3);

svdpi.h Support

The following open array related functions are supported in svdpi.h:

int svLeft(const svOpenArrayHandle h, int d);
int svRight(const svOpenArrayHandle h, int d);
int svLow(const svOpenArrayHandle h, int d);
int svHigh(const svOpenArrayHandle h, int d);
int svIncrement(const svOpenArrayHandle h, int d);
int svSize(const svOpenArrayHandle h, int d);
int svDimensions(const svOpenArrayHandle h);
void *svGetArrayPtr(const svOpenArrayHandle);
int svSizeOfArray(const svOpenArrayHandle);
void *svGetArrElemPtr(const svOpenArrayHandle, int indx1, ...);
void *svGetArrElemPtr1(const svOpenArrayHandle, int indx1);
void *svGetArrElemPtr2(const svOpenArrayHandle, int indx1, int indx2);
void *svGetArrElemPtr3(const svOpenArrayHandle, int indx1, int indx2,
int indx3);
void svPutBitArrElemVecVal(const svOpenArrayHandle d, const svBitVecVal* s,
int indx1, ...);
void svPutBitArrElem1VecVal(const svOpenArrayHandle d, const svBitVecVal* s,
int indx1);
void svPutBitArrElem2VecVal(const svOpenArrayHandle d, const svBitVecVal* s,
int indx1, int indx2);
void svPutBitArrElem3VecVal(const svOpenArrayHandle d, const svBitVecVal* s,
int indx1, int indx2, int indx3);
void svPutLogicArrElemVecVal(const svOpenArrayHandle d, const svLogicVecVal*
s, int indx1, ...);
void svPutLogicArrElem1VecVal(const svOpenArrayHandle d, const svLogicVecVal*
s, int indx1);
void svPutLogicArrElem2VecVal(const svOpenArrayHandle d, const svLogicVecVal*
s, int indx1, int indx2);
void svPutLogicArrElem3VecVal(const svOpenArrayHandle d, const svLogicVecVal*
s, int indx1, int indx2, int indx3);
void svGetBitArrElemVecVal(svBitVecVal* d, const svOpenArrayHandle s,
int indx1, ...);
void svGetBitArrElem1VecVal(svBitVecVal* d, const svOpenArrayHandle s,
int indx1);
void svGetBitArrElem2VecVal(svBitVecVal* d, const svOpenArrayHandle s,
int indx1, int indx2);
void svGetBitArrElem3VecVal(svBitVecVal* d, const svOpenArrayHandle s,
int indx1, int indx2, int indx3);
void svGetLogicArrElemVecVal(svLogicVecVal* d, const svOpenArrayHandle s,
int indx1, ...);
void svGetLogicArrElem1VecVal(svLogicVecVal* d, const svOpenArrayHandle s, int 
indx1);
void svGetLogicArrElem2VecVal(svLogicVecVal* d, const svOpenArrayHandle s,
int indx1, int indx2);
void svGetLogicArrElem3VecVal(svLogicVecVal* d, const svOpenArrayHandle s,
int indx1, int indx2, int indx3);
svBit svGetBitArrElem(const svOpenArrayHandle s, int indx1, ...);
svBit svGetBitArrElem1(const svOpenArrayHandle s, int indx1);
svBit svGetBitArrElem2(const svOpenArrayHandle s, int indx1, int indx2);
svBit svGetBitArrElem3(const svOpenArrayHandle s, int indx1, int indx2, int indx3);
svLogic svGetLogicArrElem(const svOpenArrayHandle s, int indx1, ...);
svLogic svGetLogicArrElem1(const svOpenArrayHandle s, int indx1);
svLogic svGetLogicArrElem2(const svOpenArrayHandle s, int indx1, int indx2);
svLogic svGetLogicArrElem3(const svOpenArrayHandle s, int indx1, int indx2, int 
indx3);
void svPutLogicArrElem(const svOpenArrayHandle d, svLogic value, int indx1, ...);
void svPutLogicArrElem1(const svOpenArrayHandle d, svLogic value, int indx1);
void svPutLogicArrElem2(const svOpenArrayHandle d, svLogic value, int indx1, int 
indx2);
void svPutLogicArrElem3(const svOpenArrayHandle d, svLogic value, int indx1,
int indx2, int indx3);
void svPutBitArrElem(const svOpenArrayHandle d, svBit value, int indx1, ...);
void svPutBitArrElem1(const svOpenArrayHandle d, svBit value, int indx1);
void svPutBitArrElem2(const svOpenArrayHandle d, svBit value, int indx1, int indx2);
void svPutBitArrElem3(const svOpenArrayHandle d, svBit value, int indx1,
int indx2, int indx3);

Usage Example - SystemVerilog code

module m();
import "DPI-C" function void myFunction1(input int v[]);
int arr[4];
int dynArr[];
initial begin
arr = '{4, 5, 6, 7};
myFunction1(arr);
dynArr = new[6];
dynArr = '{8, 9, 10, 11, 12, 13};
myFunction1(dynArr);
end
endmodule
C code:
#include "svdpi.h"
void myFunction1(const svOpenArrayHandle v)
{
int l1 = svLow(v, 1);
int h1 = svHigh(v, 1);
for(int i = l1; i<= h1; i++) {
    printf("\t%d", *((char*)svGetArrElemPtr1(v, i)));
}
printf("\n");
               }