camera.vhd

VHDL 实现的图像增强

ENTITY camera IS
  GENERIC(
           CONSTANT filec:   IN  STRING  := "videoinput.hex"  ;  -- Hex-video filename
           CONSTANT tclk:  IN  TIME := 100 ns;  -- Clock speed
           CONSTANT ths:     IN  INTEGER := 3;  -- Horz. sync time (in clks)
           CONSTANT tvs:     IN  INTEGER := 29;  -- Vert. sync time (in clks)
           CONSTANT tlin:     IN  INTEGER := 8);  -- Line time vert. sync
PORT(
           SIGNAL   vdat:    OUT STD_LOGIC_VECTOR (7 DOWNTO 0) ; -- Data
           SIGNAL   clk:      OUT STD_LOGIC;  -- Clock
           SIGNAL   n_hs:     OUT STD_LOGIC;  -- Horizontal sync
           SIGNAL   n_vs:     OUT STD_LOGIC;  -- Vertical sync
           SIGNAL   dv:       OUT STD_LOGIC);  -- Data valid
END camera;
---------------------------------------------------------------------------------------------
ARCHITECTURE behav OF camera IS
  SIGNAL   clkx:      STD_LOGIC      := '0' ;
  FILE     image:     hex_image_file IS IN filec;  -- File open
BEGIN
  ---- Clock generator ----------------------------------------------------------------------
  pclk: PROCESS
  BEGIN
    WAIT FOR tclk;
    clkx <= NOT(clkx);
    clk <= clkx;
  END PROCESS;
  ---- Camera simulation --------------------------------------------------------------------
  pcamera: PROCESS (clkx)
    VARIABLE cnt1: INTEGER              := 0 ; -- horz. sync counter
    VARIABLE cnt2: INTEGER              := 0 ; -- vert. sync counter
    VARIABLE cnt3: INTEGER              := 0 ; -- horz. sync in vert. sync
     
M
  BEGIN
    IF clkx = '0' THEN
      ------ Data process time, no vertical or horizontal syncs
      IF cnt1=0 AND cnt2=0 THEN
        IF not (ENDFILE (image)) THEN
          READ (image,chr1);           -- First character is read
          IF (chr1 = CR) THEN          -- CR-LF detected, horizontal sync must be generated
            READ (image,chr2);         -- Second character is read. It must be Line Feed
            vdat <= (OTHERS => '0');   -- Data is cleared
            cnt1 := ths;          -- Horizontal sync time
            n_hs <= '0';          -- Horizontal sync
            n_vs <= '1';          -- Vertical sync
            dv   <= '0';               -- Data no valid
          ELSIF chr1 = '*' THEN        -- '*' detected, vertical sync must be generated
            vdat <= (OTHERS => '0');   -- Data is cleared
            cnt2 := tvs;           -- Vertical sync time
            cnt3 := tlin;           -- Line time for vertical sync
            n_vs <= '0';           -- Vertical sync
            dv   <= '0';           -- Data no valid
          ELSE                       -- Hex data
           chr2hex(chr1,hex_nib);      -- First character is converted to STD_LOGIC
           hex2std(hex_nib,idat(7 DOWNTO 4));
           READ (image,chr2);          -- Second character is read and
           chr2hex(chr2,hex_nib);     -- converted to STD_LOGIC
           hex2std(hex_nib,idat(3 DOWNTO 0));
           vdat <= idat;            -- Data out
           n_hs <= '1';            -- No horizontal sync
           n_vs <= '1';            -- No vertical sync
           dv   <= '1';             -- Data valid
         END IF;
       ELSE                        -- If end of file is reached
         ASSERT (false)
         REPORT "File end reached...";  -- Console message
         n_hs <= '1';            -- No horizontal sync
         n_vs <= '0';            -- Vertical sync
         dv   <= '0';              -- Data no valid
       END IF;
     END IF;
     ------ Horizontal sync generation
     IF cnt1>0 THEN
       n_hs <= '0';
       n_vs <= '1';
       cnt1 := cnt1-1;               -- Clock count for horizontal sync time
     ELSE
       n_hs <= '1';
     END IF;
     ------ Vertical sync generation
     IF cnt2>0 THEN
       n_vs <= '0';
       cnt2 := cnt2-1;               -- Clock count for vert. sync time
       cnt3 := cnt3-1;               -- Clock count for horz. sync time inside vert. sync
     ELSE
       n_vs <= '1';
     END IF;
     ------ Horizontal sync generation inside vertical sync
     IF cnt3=0 AND cnt2>0 THEN
       n_hs <= '0';
       cnt1 := ths-1;
       cnt3 := tlin+ths;
     END IF;
   END IF;
 END PROCESS;
END behav;