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thechaingamer
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ada-git-code

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Ada.Text_IO.Put_Line(
"row" & Integer'Image(y) & ": filter= " &
Filter_method_0'Image(current_filter)
);
end if;
--
-- !! find a way to have f99n0g04.png decoded correctly...
-- seems a filter issue.
--
case current_filter is
when None =>
-- Recon(x) = Filt(x)
u:= f;
when Sub =>
-- Recon(x) = Filt(x) + Recon(a)
if x > 0 then
for i in f'Range loop
u(u'First+j):= f(i) + mem_row_bytes(curr_row)((x-1)*bytes_to_unfilter+j);
j:= j + 1;
end loop;
else
u:= f;
end if;
when Up =>
-- Recon(x) = Filt(x) + Recon(b)
if y > 0 then
for i in f'Range loop
u(u'First+j):= f(i) + mem_row_bytes(1-curr_row)(x*bytes_to_unfilter+j);
j:= j + 1;
end loop;
else
u:= f;
end if;
when Average =>
-- Recon(x) = Filt(x) + floor((Recon(a) + Recon(b)) / 2)
for i in f'Range loop
if x > 0 then
a:= Integer(mem_row_bytes(curr_row)((x-1)*bytes_to_unfilter+j));
else
a:= 0;
end if;
if y > 0 then
b:= Integer(mem_row_bytes(1-curr_row)(x*bytes_to_unfilter+j));
else
b:= 0;
end if;
u(u'First+j):= U8((Integer(f(i)) + (a+b)/2) mod 256);
j:= j + 1;
end loop;
when Paeth =>
-- Recon(x) = Filt(x) + PaethPredictor(Recon(a), Recon(b), Recon(c))
for i in f'Range loop
if x > 0 then
a:= Integer(mem_row_bytes(curr_row)((x-1)*bytes_to_unfilter+j));
else
a:= 0;
end if;
if y > 0 then
b:= Integer(mem_row_bytes(1-curr_row)(x*bytes_to_unfilter+j));
else
b:= 0;
end if;
if x > 0 and y > 0 then
c:= Integer(mem_row_bytes(1-curr_row)((x-1)*bytes_to_unfilter+j));
else
c:= 0;
end if;
p := a + b - c;
pa:= abs(p - a);
pb:= abs(p - b);
pc:= abs(p - c);
if pa <= pb and then pa <= pc then
pr:= a;
elsif pb <= pc then
pr:= b;
else
pr:= c;
end if;
u(u'First+j):= f(i) + U8(pr);
j:= j + 1;
end loop;
end case;
j:= 0;
for i in u'Range loop
mem_row_bytes(curr_row)(x*bytes_to_unfilter+j):= u(i);
j:= j + 1;
end loop;
-- if u'Length /= bytes_to_unfilter then
-- raise Constraint_Error;
-- end if;
end Unfilter_bytes;
filter_stat: array(Filter_method_0) of Natural:= (others => 0);
----------------------------------------------
-- ** 8: Interlacing and pass extraction ** --
----------------------------------------------
-- http://www.w3.org/TR/PNG/#8Interlace
-- Output bytes from decompression