library ieee;
use ieee.math_real.all;
use ieee.numeric_std.all;
use ieee.std_logic_1164.all;

entity Shifter is
  port(
    shift_lsl : in  Std_Logic;
    shift_lsr : in  Std_Logic;
    
    shift_asr : in  Std_Logic;
    
    shift_ror : in  Std_Logic; -- rotation sans extension
    shift_rrx : in  Std_Logic; -- avec extension
    
    shift_val : in  Std_Logic_Vector(4 downto 0);
    
    din       : in  Std_Logic_Vector(31 downto 0);
    cin       : in  Std_Logic;
    
    dout      : out Std_Logic_Vector(31 downto 0);
    cout      : out Std_Logic;
    
    -- global interface
    vdd       : in  bit;
    vss       : in  bit );
end Shifter;

-- TODO:
-- changer les "000" et "temp_dout(31)& temp_dout(31)& ..." par la synthaxe
-- (n1 downto n0 => '0') ou (n1 downto n0 => '0') 

architecture Shifter_bhvr of Shifter is
    begin
        process(shift_lsl, shift_lsr, shift_asr, shift_ror, shift_rrx,shift_val,
                din, cin, vdd, vss)
            variable temp_dout :  Std_Logic_Vector(31 downto 0);
            variable temp_cout :  Std_Logic;
            begin
            temp_dout := din;
            temp_cout := cin;
            -- LSL -------------------------------------------------------------
            -- 1
            if(shift_lsl='1' and shift_val(0)='1') 
                         then   
                                temp_cout :=  temp_dout(31);
                                temp_dout := (temp_dout(30 downto 0)&'0');
                         else   NULL;
            end if;
            
            -- 2
            if(shift_lsl='1' and shift_val(1)='1')
                         then   
                                temp_cout :=  temp_dout(30);
                                temp_dout := (temp_dout(29 downto 0)&"00"); 
                         else   NULL;
            end if;
            
            -- 4
            if(shift_lsl='1' and shift_val(2)='1')
                         then   
                                temp_cout :=  temp_dout(28);
                                temp_dout := (temp_dout(27 downto 0)&"0000"); 
                         else   NULL;
            end if;
                         
            -- 8
            if(shift_lsl='1' and shift_val(3)='1')
                         then   
                                temp_cout :=  temp_dout(24);
                                temp_dout :=(temp_dout(23 downto 0)&"00000000"); 
                         else   NULL;
            end if;
            -- 16
            if(shift_lsl='1' and shift_val(4)='1')
                         then   
                                temp_cout :=  temp_dout(16);
                                temp_dout :=
                                    (temp_dout(15 downto 0)&"0000000000000000"); 
                         else   NULL;
            end if;
            
            -- LSR -------------------------------------------------------------
            -- 1
            if(shift_lsr='1' and shift_val(0)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := ('0'&temp_dout(31 downto 1)); 
                         else   NULL;
            end if;
            
            -- 2
            if(shift_lsr='1' and shift_val(1)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := ("00"&temp_dout(31 downto 2)); 
                         else   NULL;
            end if;
            
            -- 4
            if(shift_lsr='1' and shift_val(2)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := ("0000"&temp_dout(31 downto 4)); 
                         else   NULL;
            end if;
                         
            -- 8
            if(shift_lsr='1' and shift_val(3)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout :=("00000000"&temp_dout(31 downto 8)); 
                         else   NULL;
            end if;
            
            -- 16
            if(shift_lsr='1' and shift_val(4)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout :=
                                   ("0000000000000000"&temp_dout(31 downto 16)); 
                         else   NULL;
            end if;
            
            
            -- ASR -------------------------------------------------------------
            -- 1
            if(shift_asr='1' and shift_val(0)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := (temp_dout(31)
                                            &temp_dout(31 downto 1)); 
                         else   NULL;
            end if;
            
            -- 2
            if(shift_asr='1' and shift_val(1)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := 
                                       ( temp_dout(31)& temp_dout(31)
                                       &temp_dout(31 downto 2)); 
                         else   NULL;
            end if;
            
            -- 4
            if(shift_asr='1' and shift_val(2)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout := 
                                       ( temp_dout(31)& temp_dout(31)
                                        &temp_dout(31)& temp_dout(31)
                                        &temp_dout(27 downto 0)); 
                         else   NULL;
            end if;
                         
            -- 8
            if(shift_asr='1' and shift_val(3)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout :=
                                ( temp_dout(31)&temp_dout(31)&temp_dout(31)
                                 &temp_dout(31)&temp_dout(31)&temp_dout(31)
                                 &temp_dout(31)&temp_dout(31)
                                 &temp_dout(23 downto 0)); 
                         else   NULL;
            end if;
            
            -- 16
            if(shift_asr='1' and shift_val(4)='1')
                         then   
                                temp_cout :=  temp_dout(0);
                                temp_dout :=
                                    ( temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(31)& temp_dout(31)&
                                      temp_dout(15 downto 0)); 
                         else   NULL;
            end if;
            
            -- ROR -------------------------------------------------------------
            -- 1
            if(shift_ror='1' and shift_val(0)='1')
                         then   temp_dout := (temp_dout(0)
                                            &temp_dout(31 downto 1));
                                temp_cout := temp_dout(0);
                         else   NULL;
            end if;
            
            -- 2
            if(shift_ror='1' and shift_val(1)='1')
                         then   temp_dout := 
                                       (temp_dout(1 downto 0)
                                       &temp_dout(31 downto 2));
                                temp_cout := temp_dout(1); 
                         else   NULL;
            end if;
            
            -- 4
            if(shift_ror='1' and shift_val(2)='1')
                         then   temp_dout := 
                                       (temp_dout(3 downto 0)
                                       &temp_dout(31 downto 4));
                                temp_cout := temp_dout(3); 
                         else   NULL;
            end if;
                         
            -- 8
            if(shift_ror='1' and shift_val(3)='1')
                         then   temp_dout :=
                                (temp_dout(7 downto 0)
                                 &temp_dout(31 downto 8));
                                temp_cout := temp_dout(7);
                         else   NULL;
            end if;
            
            -- 16
            if(shift_ror='1' and shift_val(4)='1')
                         then   temp_dout :=
                                    (temp_dout(15 downto 0)
                                    &temp_dout(31 downto 16));
                                temp_cout := temp_dout(15);
                         else   NULL;
            end if;
            
            -- RRX -------------------------------------------------------------
            -- 1
            if(shift_rrx='1' and shift_val(0)='1')
                         then   temp_dout := (temp_cout
                                            &temp_dout(31 downto 1)); 
                                temp_cout := temp_dout(0);
                         else   NULL;
            end if;
            
            -- 2
            if(shift_rrx='1' and shift_val(1)='1')
                         then   temp_dout := 
                                       (temp_cout
                                       &temp_dout(0)
                                       &temp_dout(31 downto 2));
                                temp_cout := temp_dout(1); 
                         else   NULL;
            end if;
            
            -- 4
            if(shift_rrx='1' and shift_val(2)='1')
                         then   temp_dout := 
                                       (temp_cout
                                       &temp_dout(2 downto 0)
                                       &temp_dout(31 downto 4));
                                temp_cout := temp_dout(3); 
                         else   NULL;
            end if;
                         
            -- 8
            if(shift_rrx='1' and shift_val(3)='1')
                         then   temp_dout :=
                                (temp_cout
                                 &temp_dout(6 downto 0)
                                 &temp_dout(31 downto 8));
                                temp_cout := temp_dout(7); 
                         else   NULL;
            end if;
            
            -- 16
            if(shift_rrx='1' and shift_val(4)='1')
                         then   temp_dout :=
                                    (temp_cout
                                    &temp_dout(14 downto 0)
                                    &temp_dout(31 downto 16));
                                temp_cout := temp_dout(15);
                         else   NULL;
            end if;
        
        cout <= temp_cout;
        dout <= temp_dout;
        end process;
end Shifter_bhvr;