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T80: fixed DAA instruction (different from Z80)

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This commit is contained in:
Bruno Gouveia
2018-11-16 22:06:33 +00:00
parent 4d461d4be7
commit 7939e38ed9
1 changed files with 54 additions and 25 deletions
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79
t80/T80_ALU.vhd
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@@ -216,35 +216,64 @@ begin
end if;
when "1100" =>
-- DAA
F_Out(Flag_H) <= F_In(Flag_H);
F_Out(Flag_C) <= F_In(Flag_C);
DAA_Q(7 downto 0) := unsigned(BusA);
DAA_Q(8) := '0';
if F_In(Flag_N) = '0' then
-- After addition
-- Alow > 9 or H = 1
if DAA_Q(3 downto 0) > 9 or F_In(Flag_H) = '1' then
if (DAA_Q(3 downto 0) > 9) then
F_Out(Flag_H) <= '1';
else
F_Out(Flag_H) <= '0';
if Mode = 3 then
F_Out(Flag_H) <= '0';
F_Out(Flag_C) <= F_In(Flag_C);
DAA_Q(7 downto 0) := unsigned(BusA);
DAA_Q(8) := '0';
if F_In(Flag_N) = '0' then
-- After addition
-- Alow > 9 or H = 1
if DAA_Q(3 downto 0) > 9 or F_In(Flag_H) = '1' then
DAA_Q := DAA_Q + 6;
end if;
-- new Ahigh > 9 or C = 1
if DAA_Q(8 downto 4) > 9 or F_In(Flag_C) = '1' then
DAA_Q := DAA_Q + 96; -- 0x60
end if;
else
-- After subtraction
if F_In(Flag_H) = '1' then
DAA_Q := DAA_Q - 6;
if F_In(Flag_C) = '0' then
DAA_Q(8) := '0';
end if;
end if;
if F_In(Flag_C) = '1' then
DAA_Q := DAA_Q - 96; -- 0x60
end if;
DAA_Q := DAA_Q + 6;
end if;
-- new Ahigh > 9 or C = 1
if DAA_Q(8 downto 4) > 9 or F_In(Flag_C) = '1' then
DAA_Q := DAA_Q + 96; -- 0x60
end if;
else
-- After subtraction
if DAA_Q(3 downto 0) > 9 or F_In(Flag_H) = '1' then
if DAA_Q(3 downto 0) > 5 then
F_Out(Flag_H) <= '0';
F_Out(Flag_H) <= F_In(Flag_H);
F_Out(Flag_C) <= F_In(Flag_C);
DAA_Q(7 downto 0) := unsigned(BusA);
DAA_Q(8) := '0';
if F_In(Flag_N) = '0' then
-- After addition
-- Alow > 9 or H = 1
if DAA_Q(3 downto 0) > 9 or F_In(Flag_H) = '1' then
if (DAA_Q(3 downto 0) > 9) then
F_Out(Flag_H) <= '1';
else
F_Out(Flag_H) <= '0';
end if;
DAA_Q := DAA_Q + 6;
end if;
-- new Ahigh > 9 or C = 1
if DAA_Q(8 downto 4) > 9 or F_In(Flag_C) = '1' then
DAA_Q := DAA_Q + 96; -- 0x60
end if;
else
-- After subtraction
if DAA_Q(3 downto 0) > 9 or F_In(Flag_H) = '1' then
if DAA_Q(3 downto 0) > 5 then
F_Out(Flag_H) <= '0';
end if;
DAA_Q(7 downto 0) := DAA_Q(7 downto 0) - 6;
end if;
if unsigned(BusA) > 153 or F_In(Flag_C) = '1' then
DAA_Q := DAA_Q - 352; -- 0x160
end if;
DAA_Q(7 downto 0) := DAA_Q(7 downto 0) - 6;
end if;
if unsigned(BusA) > 153 or F_In(Flag_C) = '1' then
DAA_Q := DAA_Q - 352; -- 0x160
end if;
end if;
F_Out(Flag_X) <= DAA_Q(3);