Fixed sign error when extracting from signed memory

git-svn-id: file://localhost/svn/verilator/trunk/verilator@978 77ca24e4-aefa-0310-84f0-b9a241c72d87

Changes

@@ -8,6 +8,8 @@ indicates the contributor was also the author of the fix; Thanks!
 **** Wide VL_CONST_W_#X functions are now made automatically. [Bernard Deadman]
      In such cases, a new {prefix}__Inlines.h file will be built and included.
 
+**** Fixed sign error when extracting from signed memory.  [Peter Debacker]
+
 **** Fixed tracing of SystemC w/o SystemPerl. [Bernard Deadman]
 
 * Verilator 3.655 11/27/2007
@@ -91,7 +93,7 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***  Support Verilog 2005 `begin_keywords and `end_keywords.
 
-***  Updated list of SystemVerilog keywords to correspond to IEEE 1800-2008.
+***  Updated list of SystemVerilog keywords to correspond to IEEE 1800-2005.
 
 ***  Add /*verilator public_flat*/.  [Eugene Weber]
 

src/V3Signed.cpp

@@ -67,7 +67,6 @@ private:
 
     //========
     // Signed: Output unsigned, Operands either
-    virtual void visit(AstArraySel* nodep, AstNUser*) {		signed_Ou_Ix(nodep); } //See backRequiresUnsigned
     virtual void visit(AstSel* nodep, AstNUser*) {		signed_Ou_Ix(nodep); } //See backRequiresUnsigned
     virtual void visit(AstAttrOf* nodep, AstNUser*) {		signed_Ou_Ix(nodep); }
     virtual void visit(AstCountOnes* nodep, AstNUser*) {	signed_Ou_Ix(nodep); }
@@ -110,6 +109,10 @@ private:
     virtual void visit(AstShiftL* nodep, AstNUser*) {		signed_Olhs(nodep); }
     virtual void visit(AstShiftR* nodep, AstNUser*) {		signed_Olhs(nodep); }
 
+    // Signed: Output signed iff LHS signed; binary operator
+    // Note by contrast, bit extract selects are unsigned
+    virtual void visit(AstArraySel* nodep, AstNUser*) {		signed_Olhs(nodep); } //See backRequiresUnsigned
+
     //=======
     // Signed: Output signed iff LHS & RHS signed; binary operator
     virtual void visit(AstAnd* nodep, AstNUser*) {		signed_OlhsAndRhs(nodep); }
@@ -315,6 +318,11 @@ private:
 	nodep->iterateChildren(*this);
 	nodep->isSigned(nodep->lhsp()->isSigned());
     }
+    // Signed: Output signed iff LHS signed; select operator
+    void signed_Olhs(AstSel* nodep) {
+	nodep->iterateChildren(*this);
+	nodep->isSigned(nodep->fromp()->isSigned());
+    }
     // Signed: Output signed iff LHS & RHS signed; binary operator
     void signed_OlhsAndRhs(AstNodeBiop* nodep) {
 	nodep->iterateChildren(*this);

test_regress/t/t_math_signed.v

@@ -78,7 +78,9 @@ module t (/*AUTOARG*/
    wire [31:0] ucyc = cyc;
    always @ (posedge clk) begin
       cyc <= cyc + 1;
+`ifdef TEST_VERBOSE
       $write("%x  %x %x %x %x  %x %x\n", cyc, sr,srs,sl,sls, b_s,b_us);
+`endif
       case (cyc)
 	0: begin
 	   a <= 16'sh8b1b; b <= 5'sh1f;  // -1

test_regress/t/t_math_signed2.pl

@@ -0,0 +1,18 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
+# $Id$
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# General Public License or the Perl Artistic License.
+
+compile (
+	 );
+
+execute (
+	 check_finished=>1,
+     );
+
+ok(1);
+1;

test_regress/t/t_math_signed2.v

@@ -0,0 +1,67 @@
+// $Id$
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2007 by Peter Debacker.
+
+module t (/*AUTOARG*/
+  // Inputs
+  clk
+  );
+  input clk;
+
+  reg        [10:0] in;
+  reg  signed[7:0]  min;
+  reg  signed[7:0]  max;
+  wire signed[7:0]  filtered_data;
+  reg  signed[7:0]  delay_minmax[31:0];
+  integer k;
+
+  initial begin
+    in = 11'b10000001000;
+    for(k=0;k<32;k=k+1) 
+      delay_minmax[k] = 0;
+  end
+
+   assign filtered_data = $signed(in[10:3]);
+
+   always @(posedge clk) begin
+      in = in + 8;
+`ifdef TEST_VERBOSE
+      $write("filtered_data: %d\n", filtered_data);
+`endif
+      // delay line shift
+      for (k=31;k>0;k=k-1) begin
+	 delay_minmax[k] = delay_minmax[k-1];
+      end
+      delay_minmax[0] = filtered_data;
+`ifdef TEST_VERBOSE
+      $write("delay_minmax[0]  = %d\n", delay_minmax[0]);
+      $write("delay_minmax[31] = %d\n", delay_minmax[31]);
+`endif
+      // find min and max
+      min = 127;
+      max = -128;
+`ifdef TEST_VERBOSE
+      $write("max init: %d\n", max);
+      $write("min init: %d\n", min);
+`endif
+      for(k=0;k<32;k=k+1) begin
+	 if ((delay_minmax[k]) > $signed(max))
+	   max = delay_minmax[k];
+	 if ((delay_minmax[k]) < $signed(min))
+	   min = delay_minmax[k];
+      end
+`ifdef TEST_VERBOSE
+      $write("max: %d\n", max);
+      $write("min: %d\n", min);
+`endif
+      if (min == 127) begin
+	 $stop;
+      end
+      else if (filtered_data >= -61) begin
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+endmodule