Merge pull request #85 from antonblanchard/leadingzeroes-fix

Fix count-leading/trailing-zeroes

countzero.vhdl

@@ -14,86 +14,94 @@ entity zero_counter is
 end entity zero_counter;
 
 architecture behaviour of zero_counter is
-    signal l32, r32 : std_ulogic;
-    signal v32      : std_ulogic_vector(31 downto 0);
-    signal v16      : std_ulogic_vector(15 downto 0);
-    signal v8       : std_ulogic_vector(7 downto 0);
-    signal v4       : std_ulogic_vector(3 downto 0);
-    signal sel      : std_ulogic_vector(5 downto 0);
 begin
     zerocounter0: process(all)
+        variable l32, r32 : std_ulogic;
+        variable v32      : std_ulogic_vector(31 downto 0);
+        variable v16      : std_ulogic_vector(15 downto 0);
+        variable v8       : std_ulogic_vector(7 downto 0);
+        variable v4       : std_ulogic_vector(3 downto 0);
+        variable sel      : std_ulogic_vector(5 downto 0);
     begin
-	l32 <= or (rs(63 downto 32));
+        l32 := '0';
-	r32 <= or (rs(31 downto 0));
+        r32 := '0';
+        v32 := (others => '0');
+        v16 := (others => '0');
+        v8  := (others => '0');
+        v4  := (others => '0');
+        sel := (others => '0');
+
+	l32 := or (rs(63 downto 32));
+	r32 := or (rs(31 downto 0));
 	if (l32 = '0' or is_32bit = '1') and r32 = '0' then
 	    -- operand is zero, return 32 for 32-bit, else 64
 	    result <= x"00000000000000" & '0' & not is_32bit & is_32bit & "00000";
 	else
 
 	    if count_right = '0' then
-		sel(5) <= l32 and (not is_32bit);
+		sel(5) := l32 and (not is_32bit);
 	    else
-		sel(5) <= (not r32) and (not is_32bit);
+		sel(5) := (not r32) and (not is_32bit);
 	    end if;
 	    if sel(5) = '1' then
-		v32 <= rs(63 downto 32);
+		v32 := rs(63 downto 32);
 	    else
-		v32 <= rs(31 downto 0);
+		v32 := rs(31 downto 0);
 	    end if;
 
 	    if count_right = '0' then
-		sel(4) <= or (v32(31 downto 16));
+		sel(4) := or (v32(31 downto 16));
 	    else
-		sel(4) <= not (or (v32(15 downto 0)));
+		sel(4) := not (or (v32(15 downto 0)));
 	    end if;
 	    if sel(4) = '1' then
-		v16 <= v32(31 downto 16);
+		v16 := v32(31 downto 16);
 	    else
-		v16 <= v32(15 downto 0);
+		v16 := v32(15 downto 0);
 	    end if;
 
 	    if count_right = '0' then
-		sel(3) <= or (v16(15 downto 8));
+		sel(3) := or (v16(15 downto 8));
 	    else
-		sel(3) <= not (or (v16(7 downto 0)));
+		sel(3) := not (or (v16(7 downto 0)));
 	    end if;
 	    if sel(3) = '1' then
-		v8 <= v16(15 downto 8);
+		v8 := v16(15 downto 8);
 	    else
-		v8 <= v16(7 downto 0);
+		v8 := v16(7 downto 0);
 	    end if;
 
 	    if count_right = '0' then
-		sel(2) <= or (v8(7 downto 4));
+		sel(2) := or (v8(7 downto 4));
 	    else
-		sel(2) <= not (or (v8(3 downto 0)));
+		sel(2) := not (or (v8(3 downto 0)));
 	    end if;
 	    if sel(2) = '1' then
-		v4 <= v8(7 downto 4);
+		v4 := v8(7 downto 4);
 	    else
-		v4 <= v8(3 downto 0);
+		v4 := v8(3 downto 0);
 	    end if;
 
 	    if count_right = '0' then
 		if v4(3) = '1' then
-		    sel(1 downto 0) <= "11";
+		    sel(1 downto 0) := "11";
 		elsif v4(2) = '1' then
-		    sel(1 downto 0) <= "10";
+		    sel(1 downto 0) := "10";
 		elsif v4(1) = '1' then
-		    sel(1 downto 0) <= "01";
+		    sel(1 downto 0) := "01";
 		else
-		    sel(1 downto 0) <= "00";
+		    sel(1 downto 0) := "00";
 		end if;
 		result <= x"00000000000000" & "00" & (not sel(5) and not is_32bit) & not sel(4 downto 0);
 	    else
 		if v4(0) = '1' then
-		    sel(1 downto 0) <= "00";
+		    sel(1 downto 0) := "00";
 		elsif v4(1) = '1' then
-		    sel(1 downto 0) <= "01";
+		    sel(1 downto 0) := "01";
 		elsif v4(2) = '1' then
-		    sel(1 downto 0) <= "10";
+		    sel(1 downto 0) := "10";
 		else
-		    sel(1 downto 0) <= "11";
+		    sel(1 downto 0) := "11";
 		end if;
 		result <= x"00000000000000" & "00" & sel;
 	    end if;