pm_fetch_dec.vhd

avr core porocesssor vhdl source code

			  
-- INSTRUCTION DECODER (CONNECTED AFTER NOP INSERTION LOGIC)

idc_adc  <= '1' when instruction_code_reg(15 downto 10) = "000111" else '0'; -- 000111XXXXXXXXXX
idc_add  <= '1' when instruction_code_reg(15 downto 10) = "000011" else '0'; -- 000011XXXXXXXXXX

idc_adiw <= '1' when instruction_code_reg(15 downto 8) = "10010110" else '0'; -- 10010110XXXXXXXX

idc_and  <= '1' when instruction_code_reg(15 downto 10) = "001000" else '0'; -- 001000XXXXXXXXXX
idc_andi <= '1' when instruction_code_reg(15 downto 12) = "0111" else '0'; -- 0111XXXXXXXXXXXX

idc_asr  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100101" else '0'; -- 1001010XXXXX0101

idc_bclr <= '1' when instruction_code_reg(15 downto 7)&instruction_code_reg(3 downto 0) = "1001010011000" else '0'; -- 100101001XXX1000

idc_bld  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3) = "11111000" else '0'; -- 1111100XXXXX0XXX

idc_brbc <= '1' when instruction_code_reg(15 downto 10) = "111101" else '0'; -- 111101XXXXXXXXXX
idc_brbs <= '1' when instruction_code_reg(15 downto 10) = "111100" else '0'; -- 111100XXXXXXXXXX

idc_bset <= '1' when instruction_code_reg(15 downto 7)&instruction_code_reg(3 downto 0) = "1001010001000" else '0'; -- 100101000XXX1000

idc_bst  <= '1' when instruction_code_reg(15 downto 9) = "1111101" else '0'; -- 1111101XXXXXXXXX

idc_call <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 1) = "1001010111" else '0'; -- 1001010XXXXX111X

idc_cbi  <= '1' when instruction_code_reg(15 downto 8) = "10011000" else '0'; -- 10011000XXXXXXXX

idc_com  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100000" else '0'; -- 1001010XXXXX0000

idc_cp   <= '1' when instruction_code_reg(15 downto 10) = "000101" else '0'; -- 000101XXXXXXXXXX

idc_cpc  <= '1' when instruction_code_reg(15 downto 10) = "000001" else '0'; -- 000001XXXXXXXXXX

idc_cpi  <= '1' when instruction_code_reg(15 downto 12) = "0011" else '0'; -- 0011XXXXXXXXXXXX

idc_cpse <= '1' when instruction_code_reg(15 downto 10) = "000100" else '0'; -- 000100XXXXXXXXXX

idc_dec  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010101010" else '0'; -- 1001010XXXXX1010

idc_elpm <= '1' when instruction_code_reg = "1001010111011000" else '0'; -- 1001010111011000

idc_eor  <= '1' when instruction_code_reg(15 downto 10) = "001001" else '0'; -- 001001XXXXXXXXXX

idc_icall<= '1' when instruction_code_reg(15 downto 8)&instruction_code_reg(3 downto 0) = "100101011001" else '0'; -- 10010101XXXX1001

idc_ijmp <= '1' when instruction_code_reg(15 downto 8)&instruction_code_reg(3 downto 0) = "100101001001" else '0'; -- 10010100XXXX1001

idc_in   <= '1' when instruction_code_reg(15 downto 11) = "10110" else '0'; -- 10110XXXXXXXXXXX

idc_inc  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100011" else '0'; -- 1001010XXXXX0011

idc_jmp  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 1) = "1001010110" else '0'; -- 1001010XXXXX110X


-- LD,LDD 
idc_ld_x <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010001100" or 
                     instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010001101"	or
					 instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010001110" else '0';
		
idc_ld_y <= '1' when (instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10000001000" or
                      instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010001001" or 
					  instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010001010") else '0'; 

idc_ldd_y<= '1' when instruction_code_reg(15 downto 14)&instruction_code_reg(12)&instruction_code_reg(9)&instruction_code_reg(3) = "10001" else '0'; -- 10X0XX0XXXXX1XXX    

idc_ld_z <= '1' when (instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10000000000" or
                      instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010000001" or 
					  instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010000010") else '0'; 

idc_ldd_z<= '1' when instruction_code_reg(15 downto 14)&instruction_code_reg(12)&instruction_code_reg(9)&instruction_code_reg(3) = "10000" else '0'; -- 10X0XX0XXXXX0XXX       
-- ######


idc_ldi <= '1' when instruction_code_reg(15 downto 12) = "1110" else '0'; -- 1110XXXXXXXXXXXX

idc_lds <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010000000" else '0'; -- 1001000XXXXX0000

idc_lpm <= '1' when instruction_code_reg = "1001010111001000" else '0'; -- 1001010111001000

idc_lsr <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100110" else '0'; -- 1001010XXXXX0110

idc_mov <= '1' when instruction_code_reg(15 downto 10) = "001011" else '0'; -- 001011XXXXXXXXXX

idc_mul <= '1' when instruction_code_reg(15 downto 10) = "100111" else '0'; -- 100111XXXXXXXXXX

idc_neg <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100001" else '0'; -- 1001010XXXXX0001

idc_nop <= '1' when instruction_code_reg = "0000000000000000" else '0'; -- 0000000000000000

idc_or  <= '1' when instruction_code_reg(15 downto 10) = "001010" else '0'; -- 001010XXXXXXXXXX

idc_ori <= '1' when instruction_code_reg(15 downto 12) = "0110" else '0'; -- 0110XXXXXXXXXXXX 

idc_out <= '1' when instruction_code_reg(15 downto 11) = "10111" else '0'; -- 10111XXXXXXXXXXX

idc_pop <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010001111" else '0'; -- 1001000XXXXX1111

idc_push<= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010011111" else '0'; -- 1001001XXXXX1111

idc_rcall<= '1' when instruction_code_reg(15 downto 12) = "1101" else '0'; -- 1101XXXXXXXXXXXX

idc_ret  <= '1' when instruction_code_reg(15 downto 7)&instruction_code_reg(4 downto 0) = "10010101001000" else '0'; -- 100101010XX01000

idc_reti <= '1' when instruction_code_reg(15 downto 7)&instruction_code_reg(4 downto 0) = "10010101011000" else '0'; -- 100101010XX11000

idc_rjmp <= '1' when instruction_code_reg(15 downto 12) = "1100" else '0'; -- 1100XXXXXXXXXXXX

idc_ror  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100111" else '0'; -- 1001010XXXXX0111

idc_sbc  <= '1' when instruction_code_reg(15 downto 10) = "000010" else '0'; -- 000010XXXXXXXXXX

idc_sbci <= '1' when instruction_code_reg(15 downto 12) = "0100" else '0'; -- 0100XXXXXXXXXXXX

idc_sbi  <= '1' when instruction_code_reg(15 downto 8) = "10011010" else '0'; -- 10011010XXXXXXXX

idc_sbic <= '1' when instruction_code_reg(15 downto 8) = "10011001" else '0'; -- 10011001XXXXXXXX

idc_sbis <= '1' when instruction_code_reg(15 downto 8) = "10011011" else '0'; -- 10011011XXXXXXXX

idc_sbiw <= '1' when instruction_code_reg(15 downto 8) = "10010111" else '0'; -- 10010111XXXXXXXX

idc_sbrc <= '1' when instruction_code_reg(15 downto 9) = "1111110" else '0'; -- 1111110XXXXXXXXX

idc_sbrs <= '1' when instruction_code_reg(15 downto 9) = "1111111" else '0'; -- 1111111XXXXXXXXX

idc_sleep<= '1' when instruction_code_reg(15 downto 5)&instruction_code_reg(3 downto 0) = "100101011001000" else '0'; -- 10010101100X1000


-- ST,STD
idc_st_x <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010011100" or 
                     instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010011101" or 
                     instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010011110" else '0';
	
idc_st_y <= '1' when (instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10000011000" or
                      instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010011001" or 
					  instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010011010") else '0'; 

idc_std_y<= '1' when instruction_code_reg(15 downto 14)&instruction_code_reg(12)&instruction_code_reg(9)&instruction_code_reg(3) = "10011" else '0'; -- 10X0XX1XXXXX1XXX    

idc_st_z <= '1' when (instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10000010000" or
                      instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010010001" or 
					  instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0)="10010010010") else '0'; 

idc_std_z<= '1' when instruction_code_reg(15 downto 14)&instruction_code_reg(12)&instruction_code_reg(9)&instruction_code_reg(3) = "10010" else '0'; -- 10X0XX1XXXXX0XXX 
-- ######

idc_sts  <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010010000" else '0'; -- 1001001XXXXX0000

idc_sub  <= '1' when instruction_code_reg(15 downto 10) = "000110" else '0'; -- 000110XXXXXXXXXX

idc_subi <= '1' when instruction_code_reg(15 downto 12) = "0101" else '0'; -- 0101XXXXXXXXXXXX

idc_swap <= '1' when instruction_code_reg(15 downto 9)&instruction_code_reg(3 downto 0) = "10010100010" else '0'; -- 1001010XXXXX0010

idc_wdr  <= '1' when instruction_code_reg(15 downto 5)&instruction_code_reg(3 downto 0) = "100101011011000" else '0'; -- 10010101101X1000

-- ADDITIONAL SIGNALS
idc_psinc <= '1' when (instruction_code_reg(1 downto 0) = "01" and 
 (idc_st_x or idc_st_y or idc_st_z or idc_ld_x or idc_ld_y or idc_ld_z)='1') else '0';  -- POST INCREMENT FOR LD/ST INSTRUCTIONS

idc_prdec <= '1' when (instruction_code_reg(1 downto 0)	= "10" and
 (idc_st_x or idc_st_y or idc_st_z or idc_ld_x or idc_ld_y or idc_ld_z)='1') else '0';  -- PRE DECREMENT FOR LD/ST INSTRUCTIONS 
				
	
-- ##########################################################################################################

-- WRITE ENABLE SIGNALS FOR ramadr_reg
ramadr_reg_en <= idc_ld_x or idc_ld_y or idc_ldd_y or idc_ld_z or idc_ldd_z or lds_st1 or    -- LD/LDD/LDS 
                 idc_st_x or idc_st_y or idc_std_y or idc_st_z or idc_std_z or sts_st1 or    -- ST/STS/STS
				 idc_push or idc_pop or
				 idc_rcall or (rcall_st1 and not cpuwait) or idc_icall or (icall_st1 and not cpuwait) or -- RCALL/ICALL
				 call_st1 or  (call_st2 and not cpuwait) or irq_st1 or (irq_st2 and not cpuwait) or  -- CALL/IRQ
				 idc_ret or (ret_st1 and not cpuwait ) or idc_reti or (reti_st1 and not cpuwait);		  -- RET/RETI  -- ??


-- RAMADR MUX
ramadr_reg_in <= sph_out&spl_out when 
  (idc_rcall or (rcall_st1 and not cpuwait)or idc_icall or (icall_st1 and not cpuwait)or  -- RCALL/ICALL
   call_st1  or (call_st2 and not cpuwait) or irq_st1   or (irq_st2 and not cpuwait)  or  -- CALL/IRQ
   idc_push )='1' else 	                                                                  -- PUSH

  (sph_out&spl_out)+1 when (idc_ret or (ret_st1 and not cpuwait)  or idc_reti  or (reti_st1 and not cpuwait) or idc_pop)='1' else  -- RET/RETI/POP

instruction_reg when (lds_st1 or sts_st1) ='1' else                                             -- LDS/STS
 reg_h_out when (idc_ld_x or idc_ld_y or idc_ld_z or idc_st_x or idc_st_y or idc_st_z)='1' else  -- LD/ST	  
 (reg_h_out + ("000000000"&dex_adr_disp));                                                       -- LDD/STD  
	  
								
-- ADDRESS REGISTER								
ramadr_reg:process(clk,nrst)
begin
if nrst='0' then 
ramadr_int <= (others => '0');
elsif(clk='1' and clk'event) then
if (ramadr_reg_en='1') then                            -- CLOCK ENABLE
ramadr_int <= ramadr_reg_in;
end if;
end if;
end process;

ramadr <= ramadr_int;

-- GENERAL PURPOSE REGISTERS ADDRESSING FLAG FOR ST/STD/STS INSTRUCTIONS
gp_reg_adr:process(clk,nrst)
begin
if nrst='0' then 
reg_file_adr_space <='0';
elsif(clk='1' and clk'event) then
if (ramadr_reg_en='1') then                            -- CLOCK ENABLE
if (ramadr_reg_in(15 downto 5)=const_ram_to_reg) then 
reg_file_adr_space <= '1';                             -- ADRESS RANGE 0x0000-0x001F -> REGISTERS (R0-R31)
else 
reg_file_adr_space <= '0';
end if;
end if;
end if;
end process;

-- I/O REGISTERS ADDRESSING FLAG FOR ST/STD/STS INSTRUCTIONS
io_reg_adr:process(clk,nrst)
begin
if nrst='0' then io_file_adr_space<='0';
elsif(clk='1' and clk'event) then
if (ramadr_reg_en='1') then                           -- CLOCK ENABLE
if (ramadr_reg_in(15 downto 5)=const_ram_to_io_a or ramadr_reg_in(15 downto 5)=const_ram_to_io_b) then 
io_file_adr_space <= '1';                             -- ADRESS RANGE 0x0020-0x005F -> I/O PORTS (0x00-0x3F)
else 
io_file_adr_space <= '0';
end if;
end if;
end if;
end process;



-- ##########################################################################################################


-- REGRE/REGWE LOGIC (5 BIT ADDSRESS BUS (INTERNAL ONLY) 32 LOCATIONS (R0-R31))

-- WRITE ENABLE FOR Rd REGISTERS 
alu_reg_wr <= idc_adc or idc_add or idc_adiw or adiw_st or idc_sub or idc_subi or idc_sbc or idc_sbci or
              idc_sbiw or  sbiw_st or idc_and or idc_andi or idc_or or idc_ori or idc_eor or idc_com or
   			  idc_neg or idc_inc or idc_dec or idc_lsr or idc_ror or idc_asr or idc_swap;
			  

reg_rd_wr <= idc_in or alu_reg_wr or idc_bld or             -- ALU INSTRUCTIONS + IN/BLD INSRTRUCTION                
 (pop_st or ld_st or lds_st2)or			                    -- POP/LD/LDD/LDS INSTRUCTIONS
 ((st_st or sts_st2) and reg_file_adr_space)or              -- ST/STD/STS INSTRUCTION 	      
  lpm_st2 or idc_ldi or idc_mov;                            -- LPM/LDI/MOV INSTRUCTION
 
  
  reg_rd_adr <= '1'&dex_adrreg_d(3 downto 0) when (idc_subi or idc_sbci or idc_andi or idc_ori or idc_cpi or idc_ldi)='1' else
			   "00000" when lpm_st2='1' else 
               adiw_sbiw_encoder_out     when (idc_adiw or idc_sbiw)='1' else
               adiw_sbiw_encoder_mux_out when (adiw_st or sbiw_st)='1' else
			   dex_adrreg_d_latched      when (((st_st or sts_st2) and not reg_file_adr_space) or ld_st or lds_st2 or pop_st)='1' else
               ramadr_int(4 downto 0)    when ((st_st or sts_st2) and reg_file_adr_space)='1'else --!!??
			   dex_adrreg_d;

reg_rr_adr <= ramadr_int(4 downto 0) when ((ld_st or lds_st2) and reg_file_adr_space)='1'else --!!??
	          dex_adrreg_d_latched   when ((st_st or sts_st2) and reg_file_adr_space)='1'else --!!??
	          dex_adrreg_r;		   
  
-- MULTIPLEXER FOR REGISTER FILE Rd INPUT
reg_rd_in <= dbusin when (idc_in or ((lds_st2 or ld_st)and not reg_file_adr_space) or pop_st)='1' else -- FROM INPUT DATA BUS
			 reg_rr_out when ((lds_st2 or ld_st)  and reg_file_adr_space)='1' else
             gp_reg_tmp when ((st_st or sts_st2)  and reg_file_adr_space)='1' else -- ST/STD/STS &  ADDRESS FROM 0 TO 31 (REGISTER FILE)
			 bld_op_out when (idc_bld='1')else                                     -- FROM BIT PROCESSOR BLD COMMAND
             reg_rr_out when (idc_mov='1')else                                     -- FOR MOV INSTRUCTION 
			 instruction_reg(15 downto 8) when (lpm_st2='1' and reg_z_out(0)='1') else -- LPM/ELPM
			 instruction_reg(7 downto 0) when  (lpm_st2='1' and reg_z_out(0)='0') else -- LPM/ELPM
             dex_dat8_immed when idc_ldi='1' else
			 alu_data_out;                                               -- FROM ALU DATA OUT

-- IORE/IOWE LOGIC (6 BIT ADDRESS adr[5..0] FOR I/O PORTS(64 LOCATIONS))
iore_int <= idc_in or idc_sbi or idc_cbi or idc_sbic or idc_sbis or ((ld_st or lds_st2) and io_file_adr_space);   -- IN/SBI/CBI 
iowe_int <= '1' when ((idc_out or sbi_st or cbi_st) or 
                     ((st_st or sts_st2) and io_file_adr_space))='1' else '0'; -- OUT/SBI/CBI + !! ST/STS/STD


-- adr[5..0] BUS MULTIPLEXER
adr_int <= dex_adr6port when (idc_in or idc_out) = '1' else                          -- IN/OUT INSTRUCTIONS  
           '0'&dex_adr5port when (idc_cbi or idc_sbi or idc_sbic or idc_sbis) ='1'    else  -- CBI/SBI (READ PHASE) + SBIS/SBIC
		   '0'&cbi_sbi_io_adr_tmp when (cbi_st or sbi_st)='1' else	-- CBI/SBI (WRITE PHASE)
		    ramadr_int(6)&ramadr_int(4 downto 0);                                                   -- LD/LDS/LDD/ST/STS/STD