Add VPI examples

examples/log2-vpi-common-vpi/vpi_log2.c

@@ -0,0 +1,67 @@
+#include <math.h>
+#include <stdlib.h>
+#include <vpi_user.h>
+
+/* --------------------------- VPI INTERFACE -------------------------------- */
+
+#define MAX_ARGS 8
+
+static int calltf(char *user_data)
+{
+    vpiHandle systfref, arg_iter;
+    vpiHandle arg_hndl[MAX_ARGS];
+    struct t_vpi_value argval;
+    int arg_cnt = 0;
+
+    for (int i = 0; i < MAX_ARGS; i++)
+        arg_hndl[i] = NULL;
+
+    systfref = vpi_handle(vpiSysTfCall, NULL);
+    arg_iter = vpi_iterate(vpiArgument, systfref);
+
+    /* ---- Get agruments ---- */
+    if (arg_iter != NULL)
+        while (arg_cnt < MAX_ARGS &&
+               NULL != (arg_hndl[arg_cnt] = vpi_scan(arg_iter)))
+            arg_cnt++;
+
+    // function $log2
+    if (arg_cnt != 1)
+        vpi_printf("ERROR: $log2() wrong argument count\n");
+    else {
+        double arg, ret;
+
+        // get argument
+        argval.format = vpiRealVal;
+        vpi_get_value(arg_hndl[0], &argval);
+        arg = argval.value.real;
+
+        ret = log2(arg);
+
+        // put return value
+        argval.format     = vpiRealVal;
+        argval.value.real = ret;
+        vpi_put_value(systfref, &argval, NULL, vpiNoDelay);
+    }
+
+    for (int i = 0; i < MAX_ARGS; i++)
+        if (arg_hndl[i]) vpi_free_object(arg_hndl[i]);
+
+    return 0;
+}
+
+static void register_interface(void)
+{
+    s_vpi_systf_data tf_data;
+
+    tf_data.type        = vpiSysFunc;
+    tf_data.sysfunctype = vpiRealFunc;
+    tf_data.compiletf   = 0;
+    tf_data.sizetf      = 0;
+    tf_data.calltf      = calltf;
+    tf_data.tfname      = "$log2";
+    vpi_register_systf(&tf_data);
+}
+
+typedef void (*stfunc)(void);
+stfunc vlog_startup_routines[] = {register_interface, 0};