modified: first approach to pointers. not finished, alu missing etc.

[calu.git] / cpu / src / extension_b.vhd

diff --git a/cpu/src/extension_b.vhd b/cpu/src/extension_b.vhd
index a035511b1284e489e2d14ee37d95175ace76c738..0c18a7de2da98d6ab9b8a0348d769442436130f1 100644 (file)
--- a/cpu/src/extension_b.vhd
+++ b/cpu/src/extension_b.vhd
@@ -11,26 +11,105 @@ use work.extension_pkg.all;
 architecture behav of extension_gpm is
 type gpm_internal is record
         status : status_rec;
+       preg : pointers_t;
 end record gpm_internal;
 
 signal reg, reg_nxt : gpm_internal;
 
+
 begin
 syn : process (clk, reset)
 begin
         if (reset = RESET_VALUE) then
                 reg.status <= ('0','0','0','0');
+               reg.pointers <= (others => (std_logic_vector(to_unsigned(DATA_END_ADDR,DATA_ADDR_WIDTH)));
         elsif rising_edge(clk) then
                 reg <= reg_nxt;
         end if;
 end process syn;
 
-asyn : process (clk, reset, alu_nxt)
+asyn : process (clk, reset, reg, alu_nxt, ext_reg, pval, pwr_en, pinc, paddr)
+       variable reg_nxt_v : gpm_internal;
+       variable incb : gp_register_t;
+       variable sel_pval : gp_register_t;
 begin
-        reg_nxt.status <= alu_nxt.status;
-end process asyn;
+       reg_nxt_v := reg;
+
+       psw <= reg.status;
+       data_out <= (others => '0');
+
+       incb := (others => '0');
+       incb(0) := '1';
+       if pinc = '1' then
+               incb := (others => '1');
+       end if;
+
+       if (ext_reg.sel = '1') and ext_reg.wr_en = '1' then
+               case ext_reg.addr(1 downto 0) is
+               when "00" => 
+                       if ext_reg.byte_en(0) = '1' then
+                               reg_nxt_v.psw := (ext_reg.data(0),ext_reg.data(1),ext_reg.data(3),ext_reg.data(2));
+                               psw <= reg_nxt_v.psw;
+                       end if;
+               when "01" =>
+                       --STACK_POINTER
+                       if ext_reg.byte_en(0) = '1' then
+                               reg_next_v.preg(0)(byte_t'range) := ext_reg.data(byte_t'range);
+                       end if;
+                       if ext_reg.byte_en(1) = '1' then
+                               reg_next_v.preg(0)((byte_t'length*2)-1 downto byte_t'length) :=
+                                       ext_reg.data((byte_t'length*2)-1 downto byte_t'length) ;
+                       end if;
+                       if ext_reg.byte_en(2) = '1' then
+                               reg_next_v.preg(0)((byte_t'length*3)-1 downto byte_t'length*2) :=
+                                       ext_reg.data((byte_t'length*3)-1 downto byte_t'length*2) ;
+                       end if;
+                       if ext_reg.byte_en(3) = '1' then
+                               reg_next_v.preg(0)((byte_t'length*4)-1 downto byte_t'length*3) :=
+                                       ext_reg.data((byte_t'length*4)-1 downto byte_t'length*3) ;
+                       end if;
+               when others => null;
+               end case;
+       end if;
 
-psw <= reg.status;
+       if (ext_reg.sel = '1') and wr_en = '0' then
+               case ext_reg.addr(1 downto 0) is
+               when "00" => 
+                       if ext_reg.byte_en(0) = '1' then
+                               data_out(3 downto 0) <= (reg.status.sign, reg.status.carry, reg.status.oflo, reg.status.zero);
+                       end if;
+               when "01" =>
+                       --STACK_POINTER
+                       if ext_reg.byte_en(0) = '1' then
+                               data_out(byte_t'range) <= reg.preg(0)(byte_t'range);
+                       end if;
+                       if ext_reg.byte_en(1) = '1' then
+                               data_out((byte_t'length*2)-1 downto byte_t'length) <=
+                                       reg_preg(0)((byte_t'length*2)-1 downto byte_t'length) ;
+                       end if;
+                       if ext_reg.byte_en(2) = '1' then
+                               data_out((byte_t'length*3)-1 downto 2*byte_t'length) <=
+                                       reg_preg(0)((byte_t'length*3)-1 downto 2*byte_t'length) ;
+                       end if;
+                       if ext_reg.byte_en(3) = '1' then
+                               data_out((byte_t'length*4)-1 downto 3*byte_t'length) <=
+                                       reg_preg(0)((byte_t'length*4)-1 downto 3*byte_t'length) ;
+                       end if;
+               when others => null;
+               end case;
+       end if;
+
+
+       sel_pval := reg_nxt_v.preg(unsigned(paddr));
+       pval <= sel_pval;
+       if pwr_en = '1' then
+               reg_nxt_v.preg(to_integer(unsigned(paddr))) := std_logic_vector(unsigned(sel_pval)+unsigned(incb));
+       end if;
+
+       reg_nxt_v.status := alu_nxt.status;
+       
+       reg_nxt <= reg_nxt_v;
+end process asyn;
 
 end behav;