is there any API to convert "svLogicVecVal *" to "uint_8"?

Question

my input in systemverilog is in bits; but I need it to be in uint8_t. is API or library can do it? FYI, Im trying to verify verilog results with .C using "dpi".

system verilog:

//import "DPI-C" function int test_encrypt_ecb();

import "DPI-C" function void compute_bit(input bit i_value, output bit result);
import "DPI-C" function bit get_bit(input bit i_value);
import "DPI-C" function void compute_logic_vector(reg[127:0] i_value, reg[127:0] result, int asize);

c:


void compute_reg_vector(const svLogicVecVal* i_value, svLogicVecVal* result,
        int asize) {
    log_info("dpi_c.compute_reg_vector(): input %s",
            svLogicVecVal2String(i_value, asize));
    
    uint8_t key[] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f};
    int j =0;
    struct AES_ctx ctx;
    j++;
    
    AES_init_ctx(&ctx, key);
    f2(&ctx, i_value);
    int i;
    for(i=0;i<15;i++){
    printf("ECB encrypt: ");
    memcpy(&result, i_value, 16);
    log_info("dpi_c.compute_reg_vector(): result %s",
            svLogicVecVal2String(result, asize));
}


void f2(const struct AES_ctx* ctx, uint8_t* buf)
{
 
  Cipher((state_t*)buf, ctx->Ry);
}

error of c compilation

warning: passing argument 2 of \f2\u2019 from incompatible pointer type [enabled by default]

note: expected \u2018uint8_t *\u2019 but argument is of type \u2018const struct svLogicVecVal *\u2019
 void f2(const struct AES_ctx* ctx, uint8_t* buf);

warning: \u2018main\u2019 is normally a non-static function [-Wmain]
 int main(void)

There is no `bits` datatype in SystemVerilog. Show us in exactly the SV datatype you want converted. It would also help to show example data formatted before and after conversion. — dave_59, Jan 21 '23 at 15:56
when i send hex from sv to c. i receive it as binary. the function i showed above. but in my C i need to use that input as bytes or int. i am trying to convert binary to unit_8 in C. and again back to binary to send it back to sv. — jeff, Jan 22 '23 at 09:09
Hex and binary are not datatypes, they are text formats for numeric values. Please edit your question to show what the code looks like in SystemVerilog that calls the C function. — dave_59, Jan 22 '23 at 16:57
i have updated everything and warnings too, if you see "note" causes fail — jeff, Jan 22 '23 at 17:21
You have not shown any SystemVerilog code. You have not showed us how `unit_8` or `ctx` is defined in C. We don't even know if using `svLogicVecVal` is the correct type for what you need to be doing, which we have no idea what you are trying to do. — dave_59, Jan 22 '23 at 21:10
i have updated this few days ago but didnt save. input of compute_logic_vector(x,y,z); x=128'h69c4e0d86a7b0430d8cdb78070b4c550; y=key(in C); z=16; — jeff, Jan 26 '23 at 01:43

dave_59 · Accepted Answer · 2023-01-26T16:27:20.470

There are no API functions to convert from svLogicVecVal to other C types. You have to understand the C data structure representation of a 4-state (0,1,X,Z) data type which is

typedef struct t_vpi_vecval {
  uint32_t aval; // 2-state component
  uint32_t bval; // 4-state component
} s_vpi_vecval, *p_vpi_vecval;
typedef s_vpi_vecval svLogicVecVal;

A 128-bit packed 4-state value would be stored in an array of 8 32-bit words. The aval/bval words would be interwoven. Assuming you are only dealing with 2-state values, then picking up every other 32-bit word will work for you.

However, if you know your DPI routines only need to deal with 2-state values, then your routines should use bit instead of reg/logic. Then your C routines only need to deal with svBitVecVal, which is defined as

typedef uint32_t svBitVecVal;

Which you can cast to uint8_t* as long as your arguments are multiples of 8 bits. Note for single bit arguments or return values, it is much more efficient to use C compatible types like byte/int that can be passed by value and require no pointers.

Here is a small example

SystemVerilog code:

module top;
import "DPI-C" function void compute_logic_vector(bit[127:0] i_value);

   logic [127:0] x = 128'h69c4_e0d8__6a7b_0430__d8cd_b780__70b4_c550;

   initial compute_logic_vector(x); // SV handles the 4- to 2-state conversion for you
endmodule

C code:

#include "svBitVecVal.h" // compiler generated header guarantees prototypes match
#include <stdint.h>
#include <stdio.h>

void compute_logic_vector(const svBitVecVal* i_value) {
  uint8_t* buf = (uint8_t*) i_value;
  for(int i=0;i<16;i++)
    printf("0x%x ",*buf++);
  printf("\n");
}

Command line to run Questa:

qrun svBitVecVal.sv -dpiheader svBitVecVal.h svBitVecVal.c

Output:

# 0x50 0xc5 0xb4 0x70 0x80 0xb7 0xcd 0xd8 0x30 0x4 0x7b 0x6a 0xd8 0xe0 0xc4 0x69

is there any API to convert "svLogicVecVal *" to "uint_8"?

1 Answers1