Implement substring method for string expressions.

elab_expr.cc

@@ -1675,7 +1675,7 @@ static NetExpr* check_for_struct_members(const LineInfo*li,
 }
 
 static NetExpr* check_for_class_property(const LineInfo*li,
-					 Design*des, NetScope*scope,
+					 Design*des, NetScope*,
 					 NetNet*net,
 					 const name_component_t&comp)
 {
@@ -1885,6 +1885,28 @@ NetExpr* PECallFunction::elaborate_expr_method_(Design*des, NetScope*scope,
 		  sys_expr->parm(0, new NetESignal(net));
 		  return sys_expr;
 	    }
+
+	    if (method_name == "substr") {
+		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$substr",
+						     IVL_VT_STRING, 1, 3);
+		  sys_expr->set_line(*this);
+
+		    // First argument is the source string.
+		  sys_expr->parm(0, new NetESignal(net));
+
+		  ivl_assert(*this, parms_.size() == 2);
+		  NetExpr*tmp;
+
+		  tmp = elaborate_rval_expr(des, scope, IVL_VT_BOOL,
+					    32, parms_[0], false);
+		  sys_expr->parm(1, tmp);
+
+		  tmp = elaborate_rval_expr(des, scope, IVL_VT_BOOL,
+					    32, parms_[1], false);
+		  sys_expr->parm(2, tmp);
+
+		  return sys_expr;
+	    }
       }
 
       if (netenum_t*netenum = net->enumeration()) {
@@ -2544,9 +2566,9 @@ NetExpr* PEIdent::elaborate_expr(Design*des, NetScope*scope,
       NetEvent*     eve = 0;
       const NetExpr*ex1, *ex2;
 
-      NetScope*found_in = symbol_search(this, des, scope, path_,
-					net, par, eve,
-					ex1, ex2);
+      /* NetScope*found_in = */ symbol_search(this, des, scope, path_,
+					      net, par, eve,
+					      ex1, ex2);
 
       if (net == 0) {
 	    cerr << get_fileline() << ": internal error: "

tgt-vvp/eval_string.c

@@ -86,6 +86,30 @@ static void string_ex_select(ivl_expr_t expr)
       fprintf(vvp_out, "    %%load/dar/str v%p_0;\n", sig);
 }
 
+static void string_ex_substr(ivl_expr_t expr)
+{
+      ivl_expr_t arg;
+      unsigned arg1;
+      unsigned arg2;
+      assert(ivl_expr_parms(expr) == 3);
+
+      arg = ivl_expr_parm(expr,0);
+      draw_eval_string(arg);
+
+	/* Evaluate the arguments... */
+      arg = ivl_expr_parm(expr, 1);
+      arg1 = allocate_word();
+      draw_eval_expr_into_integer(arg, arg1);
+
+      arg = ivl_expr_parm(expr, 2);
+      arg2 = allocate_word();
+      draw_eval_expr_into_integer(arg, arg2);
+
+      fprintf(vvp_out, "    %%substr %u, %u;\n", arg1, arg2);
+      clr_word(arg1);
+      clr_word(arg2);
+}
+
 void draw_eval_string(ivl_expr_t expr)
 {
 
@@ -106,6 +130,13 @@ void draw_eval_string(ivl_expr_t expr)
 	    string_ex_select(expr);
 	    break;
 
+	  case IVL_EX_SFUNC:
+	    if (strcmp(ivl_expr_name(expr), "$ivl_string_method$substr") == 0)
+		  string_ex_substr(expr);
+	    else
+		  fallback_eval(expr);
+	    break;
+
 	  default:
 	    fallback_eval(expr);
 	    break;

vvp/codes.h

@@ -189,6 +189,7 @@ extern bool of_STORE_STR(vthread_t thr, vvp_code_t code);
 extern bool of_SUB(vthread_t thr, vvp_code_t code);
 extern bool of_SUB_WR(vthread_t thr, vvp_code_t code);
 extern bool of_SUBI(vthread_t thr, vvp_code_t code);
+extern bool of_SUBSTR(vthread_t thr, vvp_code_t code);
 extern bool of_SUBSTR_V(vthread_t thr, vvp_code_t code);
 extern bool of_TEST_NUL(vthread_t thr, vvp_code_t code);
 extern bool of_VPI_CALL(vthread_t thr, vvp_code_t code);

vvp/compile.cc

@@ -236,6 +236,7 @@ static const struct opcode_table_s opcode_table[] = {
       { "%sub",    of_SUB,    3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
       { "%sub/wr", of_SUB_WR, 0,  {OA_NONE,     OA_NONE,     OA_NONE} },
       { "%subi",   of_SUBI,   3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
+      { "%substr",  of_SUBSTR,  2,{OA_BIT1,     OA_BIT2,     OA_NONE} },
       { "%substr/v",of_SUBSTR_V,3,{OA_BIT1,     OA_BIT2,     OA_NUMBER} },
       { "%test_nul",  of_TEST_NUL, 1,{OA_FUNC_PTR,OA_NONE,     OA_NONE} },
       { "%wait",   of_WAIT,   1,  {OA_FUNC_PTR, OA_NONE,     OA_NONE} },

vvp/opcodes.txt

@@ -1053,6 +1053,11 @@ This instruction operates on real values in word registers. The right
 value is popped, the left value is popped, the right is subtracted
 from the left, and the result pushed.
 
+* %substr <start>, <end>
+
+This instruction takes the substring of the top string in the string
+stack. This implements the SystemVerilog style substring. The string
+stack is popped and replaced with the result.
 
 * %substr/v <bit-l>, <sel>, <wid>
 

vvp/vthread.cc

@@ -5176,6 +5176,27 @@ bool of_SUBI(vthread_t thr, vvp_code_t cp)
       return true;
 }
 
+/*
+ * %substr <first>, <last>
+ * Pop a string, take the substring (SystemVerilog style), and return
+ * the result to the stack. This opcode actually works by editing the
+ * string in place.
+ */
+bool of_SUBSTR(vthread_t thr, vvp_code_t cp)
+{
+      int32_t first = thr->words[cp->bit_idx[0]].w_int;
+      int32_t last = thr->words[cp->bit_idx[1]].w_int;
+      string&val = thr->peek_str(0);
+
+      if (first < 0 || last < first || last >= (int32_t)val.size()) {
+	    val = string("");
+	    return true;
+      }
+
+      val = val.substr(first, last-first+1);
+      return true;
+}
+
 /*
  * %substr/v <bitl>, <index>, <wid>
  */