diff options
| -rw-r--r-- | README.md | 4 | ||||
| -rw-r--r-- | frontends/verilog/verilog_parser.y | 11 |
2 files changed, 15 insertions, 0 deletions
@@ -350,6 +350,10 @@ Verilog Attributes and non-standard features through the synthesis. When entities are combined, a new |-separated string is created that contains all the string from the original entities. +- The ``defaultvalue`` attribute is used to store default values for + module inputs. The attribute is attached to the input wire by the HDL + front-end when the input is declared with a default value. + - In addition to the ``(* ... *)`` attribute syntax, Yosys supports the non-standard ``{* ... *}`` attribute syntax to set default attributes for everything that comes after the ``{* ... *}`` statement. (Reset diff --git a/frontends/verilog/verilog_parser.y b/frontends/verilog/verilog_parser.y index 5f3d713d3..ebb4369c3 100644 --- a/frontends/verilog/verilog_parser.y +++ b/frontends/verilog/verilog_parser.y @@ -345,6 +345,12 @@ module_arg_opt_assignment: if (ast_stack.back()->children.size() > 0 && ast_stack.back()->children.back()->type == AST_WIRE) { AstNode *wire = new AstNode(AST_IDENTIFIER); wire->str = ast_stack.back()->children.back()->str; + if (ast_stack.back()->children.back()->is_input) { + AstNode *n = ast_stack.back()->children.back(); + if (n->attributes.count("\\defaultvalue")) + delete n->attributes.at("\\defaultvalue"); + n->attributes["\\defaultvalue"] = $2; + } else if (ast_stack.back()->children.back()->is_reg || ast_stack.back()->children.back()->is_logic) ast_stack.back()->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, wire, $2)))); else @@ -1360,6 +1366,11 @@ wire_name_and_opt_assign: wire_name '=' expr { AstNode *wire = new AstNode(AST_IDENTIFIER); wire->str = ast_stack.back()->children.back()->str; + if (astbuf1->is_input) { + if (astbuf1->attributes.count("\\defaultvalue")) + delete astbuf1->attributes.at("\\defaultvalue"); + astbuf1->attributes["\\defaultvalue"] = $3; + } else if (astbuf1->is_reg || astbuf1->is_logic) ast_stack.back()->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, wire, $3)))); else |