From 2cb9a2360cdfeea90668abe45f4c516e3020cee7 Mon Sep 17 00:00:00 2001
From: Prasad Joshi <prasadjoshi124@gmail.com>
Date: Tue, 5 Jul 2011 18:11:56 +0100
Subject: [PATCH] Add support for SystemVerilog style time literals

SystemVerilog has support for time literals. The time literal for
example #10ns, adds a delay of 10ns no matter the time unit currently
in effect. For more details please refer to
http://iverilog.wikia.com/wiki/Projects#SystemVerilog_Style_Time_Literals

Tested-by: Oswaldo Cadenas <oswaldo.cadenas@gmail.com>
Signed-off-by: Prasad Joshi <prasadjoshi124@gmail.com>
---
 parse.y  | 17 +++++++++++++++++
 pform.cc | 43 +++++++++++++++++++++++++++++++++++++++++++
 pform.h  |  2 ++
 3 files changed, 62 insertions(+)

diff --git a/parse.y b/parse.y
index 7000f84dd..2f66e6075 100644
--- a/parse.y
+++ b/parse.y
@@ -975,6 +975,23 @@ delay_value_simple
 		  $$ = tmp;
 		  delete[]$1;
 		}
+	| TIME_LITERAL
+		{
+			int unit;
+
+			based_size = 0;
+			$$         = 0;
+			if ($1 == 0 || !get_time_unit($1, unit))
+				yyerror(@1, "internal error: delay.");
+			else {
+				double p = pow(10, unit - pform_get_timeunit());
+				double time = atof($1) * p;
+
+				verireal *v = new verireal(time);
+				$$ = new PEFNumber(v);
+				FILE_NAME($$, @1);
+			}
+		}
 	;
 
 description
diff --git a/pform.cc b/pform.cc
index 5edddf785..05ddc3314 100644
--- a/pform.cc
+++ b/pform.cc
@@ -502,6 +502,44 @@ void pform_set_timescale(int unit, int prec,
       }
 }
 
+bool get_time_unit(const char*cp, int &unit)
+{
+	const char *c;
+	bool        rc = true;
+
+	if (strchr(cp, '_')) {
+		VLerror(yylloc, "Invalid timeunit constant ('_' is not "
+				"supported).");
+		return false;
+	}
+
+	c = strpbrk(cp, "munpfs");
+	if (!c)
+		return false;
+
+	if (*c == 's')
+		unit = 0;
+	else if (!strncmp(c, "ms", 2))
+		unit = -3;
+	else if (!strncmp(c, "us", 2))
+		unit = -6;
+	else if (!strncmp(c, "ns", 2))
+		unit = -9;
+	else if (!strncmp(c, "ps", 2))
+		unit = -12;
+	else if (!strncmp(c, "fs", 2))
+		unit = -15;
+	else {
+		rc = false;
+
+		ostringstream msg;
+		msg << "Invalid timeunit scale '" << cp << "'.";
+		VLerror(msg.str().c_str());
+	}
+
+	return rc;
+}
+
 /*
  * Get a timeunit or timeprecision value from a string.  This is
  * similar to the code in lexor.lex for the `timescale directive.
@@ -611,6 +649,11 @@ void pform_set_timeunit(const char*txt, bool in_module, bool only_check)
       }
 }
 
+int pform_get_timeunit()
+{
+	return pform_cur_module->time_unit;
+}
+
 void pform_set_timeprecision(const char*txt, bool in_module, bool only_check)
 {
       int val;
diff --git a/pform.h b/pform.h
index fff1d1b43..030e37105 100644
--- a/pform.h
+++ b/pform.h
@@ -434,6 +434,8 @@ extern void parm_to_defparam_list(const string&param);
 /*
  * Tasks to set the timeunit or timeprecision for SystemVerilog.
  */
+extern bool get_time_unit(const char*cp, int &unit);
+extern int  pform_get_timeunit();
 extern void pform_set_timeunit(const char*txt, bool in_module, bool only_check);
 extern void pform_set_timeprecision(const char*txt, bool in_module,
                                     bool only_check);