From: Clifford Wolf <clifford@clifford.at>
Date: Wed, 4 Dec 2013 20:19:54 +0000 (+0100)
Subject: Added support for $clog2 system function
X-Git-Tag: yosys-0.2.0~259
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3c220e0b3271af2505f45c9828d878a492831174;p=yosys.git

Added support for $clog2 system function
---

diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index ae2f0caae..94b588f25 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -1052,11 +1052,27 @@ skip_dynamic_range_lvalue_expansion:;
 	// replace function and task calls with the code from the function or task
 	if ((type == AST_FCALL || type == AST_TCALL) && !str.empty())
 	{
-		if (type == AST_FCALL) {
-			if (current_scope.count(str) == 0 || current_scope[str]->type != AST_FUNCTION) {
-				current_ast_mod->dumpAst(stderr, "> ");
-				log_error("Can't resolve function name `%s' at %s:%d.\n", str.c_str(), filename.c_str(), linenum);
+		if (type == AST_FCALL)
+		{
+			if (str == "\\$clog2")
+			{
+				AstNode *buf = children[0]->clone();
+				while (buf->simplify(true, false, false, stage, width_hint, sign_hint)) { }
+				if (!buf->type == AST_CONSTANT)
+					log_error("Failed to evaluate system function `%s' with non-constant value at %s:%d.\n", str.c_str(), filename.c_str(), linenum);
+
+				RTLIL::Const arg_value = buf->bitsAsConst();
+				uint32_t result = 0;
+				for (size_t i = 0; i < arg_value.bits.size(); i++)
+					if (arg_value.bits.at(i) == RTLIL::State::S1)
+						result = i;
+
+				newNode = mkconst_int(result, false);
+				goto apply_newNode;
 			}
+
+			if (current_scope.count(str) == 0 || current_scope[str]->type != AST_FUNCTION)
+				log_error("Can't resolve function name `%s' at %s:%d.\n", str.c_str(), filename.c_str(), linenum);
 		}
 		if (type == AST_TCALL) {
 			if (current_scope.count(str) == 0 || current_scope[str]->type != AST_TASK)