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ascal: fix stale right-edge pixel on the last active column #36

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ascal: fix stale right-edge pixel on the last active column #36

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38 changes: 20 additions & 18 deletions sys/ascal.vhd
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Original file line number Diff line number Diff line change
Expand Up @@ -1030,6 +1030,7 @@ ARCHITECTURE rtl OF ascal IS
SIGNAL o_poly_phase_b,o_poly_phase_b2,o_poly_phase_b3 : poly_phase_t;
SIGNAL o_v_poly_phase, o_v_poly_phase2, o_h_poly_phase, o_poly_phase, o_poly_phase1 : poly_phase_interp_t;
SIGNAL o_v_poly_pix, o_h_poly_pix, o_h_lum_pix, o_v_lum_pix : type_pix;
SIGNAL o_rlast : type_pix;
SIGNAL o_poly_lum, o_poly_lum1 : unsigned(7 DOWNTO 0);
SIGNAL o_poly_lerp_ta, o_poly_lerp_tb : signed(9 DOWNTO 0);
SIGNAL o_h_poly_t,o_h_poly_t2,o_v_poly_t : type_poly_t;
Expand Down Expand Up @@ -2837,6 +2838,7 @@ BEGIN
VARIABLE r1_v, r2_v : natural RANGE 0 TO OHRESH-1;
VARIABLE fracnn_v : std_logic;
VARIABLE o_l0_v, o_l1_v, o_l2_v, o_l3_v : type_pix;
VARIABLE opix_v : type_pix;
BEGIN
IF rising_edge(o_clk) THEN
IF o_ce='1' THEN
Expand Down Expand Up @@ -2972,46 +2974,46 @@ BEGIN
o_vs<=o_vsv(11);
o_de<=o_dev(11);
o_vbl<=o_end(11);
o_r<=x"00";
o_g<=x"00";
o_b<=x"00";
o_brd<= not o_pev(11);

opix_v := (r=>x"00", g=>x"00", b=>x"00");
CASE o_vmode(2 DOWNTO 0) IS
WHEN "000" => -- Nearest
IF MASK(MASK_NEAREST)='1' THEN
o_r<=o_v_poly_pix.r;
o_g<=o_v_poly_pix.g;
o_b<=o_v_poly_pix.b;
opix_v := o_v_poly_pix;
END IF;
WHEN "001" | "010" => -- Bilinear | Sharp Bilinear
IF MASK(MASK_BILINEAR)='1' OR
MASK(MASK_SHARP_BILINEAR)='1' THEN
o_r<=o_v_bil_pix.r;
o_g<=o_v_bil_pix.g;
o_b<=o_v_bil_pix.b;
opix_v := o_v_bil_pix;
END IF;
WHEN "011" => -- BiCubic
IF MASK(MASK_BICUBIC)='1' THEN
o_r<=o_v_bic_pix.r;
o_g<=o_v_bic_pix.g;
o_b<=o_v_bic_pix.b;
opix_v := o_v_bic_pix;
END IF;

WHEN OTHERS => -- Polyphase
IF MASK(MASK_POLY)='1' THEN
o_r<=o_v_poly_pix.r;
o_g<=o_v_poly_pix.g;
o_b<=o_v_poly_pix.b;
opix_v := o_v_poly_pix;
END IF;
END CASE;

IF o_pev(11)='0' THEN
o_r<=o_border(23 DOWNTO 16); -- Copy border colour
o_g<=o_border(15 DOWNTO 8);
o_b<=o_border(7 DOWNTO 0);
opix_v := (r=>o_border(23 DOWNTO 16),
g=>o_border(15 DOWNTO 8),
b=>o_border(7 DOWNTO 0)); -- Copy border colour
END IF;

-- The line buffer fill can lag the read by one pixel at the last
-- active column when horizontal blanking is tight, giving a stale
-- right-edge pixel. Repeat the previous (valid) pixel there.
IF o_pev(11)='1' AND o_pev(10)='0' THEN
o_r<=o_rlast.r; o_g<=o_rlast.g; o_b<=o_rlast.b;
ELSE
o_r<=opix_v.r; o_g<=opix_v.g; o_b<=opix_v.b;
END IF;
o_rlast<=opix_v;

----------------------------------------------------
END IF;
END IF;
Expand Down