Yosys DPI

Makefile

LIB_NAME = my_lib
SOURCES = my_lib.c

$(LIB_NAME).so: $(SOURCES)
	gcc -O2 -shared -o $(LIB_NAME).so $(SOURCES)

my_lib.c

#include <stdio.h>
#include <string.h>
#include <math.h>

int clog2(int x)
{
    return (int)ceil(log2(x));
}

static void strrev_inplace(char *str)
{
    char t;
    int l = 0;
    int r = strlen(str) - 1;

    while (l < r) {
	t = str[l];
	str[l++] = str[r];
	str[r--] = t;
    }
}

static void chandle_string(unsigned long prefix, char *s)
{
    s[8] = '\0';
    strncpy(s, (char*)(&prefix), 8);
    strrev_inplace(s);
}

int print_int1(unsigned long prefix, int val)
{
    char s[9];

    chandle_string(prefix, s);
    printf("--- %s %i\n", s, val);
    return val;
}

int print_int2(unsigned long prefix, int val1, int val2)
{
    char s[9];

    chandle_string(prefix, s);
    printf("--- %s %i %i\n", s, val1, val2);
    return val1;
}

int sin_int(int phase, int phase_scale, int output_scale)
{
    double a = 2.0 * M_PI * (double)phase / (double)phase_scale;
    double s = sin(a) * (double)output_scale;

    return (int)s;
}

int ceiling(double x)
{
    return (int)ceil(x);
}

static int iter_i;
static int iter_limit;

void iter_init(int limit)
{
    iter_i = 0;
    iter_limit = limit;
}

int iter(void)
{
    int ii = iter_i;

    if (++iter_i >= iter_limit) iter_i = 0;

    return ii;
}

int iterator(int limit)
{
    static int i = 0;
    int ii = i;

    if (++i >= limit) i = 0;

    return ii;
}

yosys_dpi_test.sv

module yosys_dpi_test #(parameter SIZE = 100)
    (clock, i_addr, o_data);

    import "DPI-C" function integer clog2 (integer);
    import "DPI-C" function integer sin_int (integer, integer, integer);
    import "DPI-C" function integer ceiling (real);
    import "DPI-C" function integer iterator (integer);
    import "DPI-C" function integer iter_init (integer); // void function
    import "DPI-C" function integer iter;

    localparam AWIDTH = clog2(SIZE);
    localparam TWOPI = ceiling(3.1415926 * 2.0);
    localparam I0 = iterator(10);
    localparam I1 = iterator(10);

    initial begin
        integer unused, N0, N1;
        unused = iter_init(20);
        N0 = iter();
        N1 = iter();
    end

    initial begin
        $display("SIZE = %0d", SIZE);
        $display("AWIDTH = %0d", AWIDTH);
    end

    input wire clock;
    input wire [AWIDTH-1:0] i_addr;
    output reg [7:0] o_data;

    logic signed [7:0] rom[SIZE];

    initial begin
        for (int n = 0; n < SIZE; n ++)
          rom[n] = 8'(sin_int(n, SIZE, 127));
    end

    always_ff @(posedge clock)
      o_data <= rom[i_addr];

endmodule

yosys_dpi_test.ys

plugin -i my_lib.so
read -sv2012 yosys_dpi_test.sv

hierarchy -check -top yosys_dpi_test
proc
synth_ice40