Revision 317
Added by markw almost 11 years ago
| sockit/avalon_atari_dma.vhd | ||
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ARCHITECTURE vhdl OF avalon_atari_dma IS
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SIGNAL BYTE_ADDRESS : STD_LOGIC_VECTOR(1 downto 0);
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SIGNAL SPECIAL_MEM : STD_LOGIC;
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SIGNAL DMA_MEMORY_DATA_LOW : STD_LOGIC_VECTOR(7 downto 0);
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BEGIN
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DMA_FETCH <= (READ or WRITE) and CHIPSELECT;
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DMA_READ_ENABLE <= READ;
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DMA_ADDR <= ADDRESS&BYTE_ADDRESS;
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WAITREQUEST <= NOT(MEMORY_READY_DMA) or not(RESET_N);
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process(BYTEENABLE, DMA_MEMORY_DATA, WRITEDATA)
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process(ADDRESS)
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begin
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special_mem <= '0';
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-- $00000-$0FFFF = Own ROM/RAM
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-- $10000-$1FFFF = Atari
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-- $20000-$2FFFF = Atari - savestate (gtia/antic/pokey have memory behind them)
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if (or_reduce(std_logic_vector(ADDRESS(21 downto 19))) = '0') then -- special area
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special_mem <= ADDRESS(15);
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end if;
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end process;
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process(SPECIAL_MEM, DMA_MEMORY_DATA)
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begin
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DMA_MEMORY_DATA_LOW <= DMA_MEMORY_DATA(7 downto 0);
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if (SPECIAL_MEM = '1') then
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DMA_MEMORY_DATA_LOW <= DMA_MEMORY_DATA(15 downto 8);
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end if;
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end process;
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process(BYTEENABLE, DMA_MEMORY_DATA_LOW, WRITEDATA, SPECIAL_MEM)
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begin
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BYTE_ADDRESS <= "00";
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DMA_8BIT_WRITE_ENABLE <= '0';
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DMA_32BIT_WRITE_ENABLE <= '0';
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| ... | ... | |
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case BYTEENABLE is
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when "0001" =>
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DMA_8BIT_WRITE_ENABLE <= '1';
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READDATA <= DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0);
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READDATA <= DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW;
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DMA_WRITE_DATA <= x"000000"&WRITEDATA(7 downto 0);
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when "0010" =>
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BYTE_ADDRESS <= "01";
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DMA_8BIT_WRITE_ENABLE <= '1';
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READDATA <= DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0);
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READDATA <= DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW;
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DMA_WRITE_DATA <= x"000000"&WRITEDATA(15 downto 8);
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when "0100" =>
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BYTE_ADDRESS <= "10";
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DMA_8BIT_WRITE_ENABLE <= '1';
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READDATA <= DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0);
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READDATA <= DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW;
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DMA_WRITE_DATA <= x"000000"&WRITEDATA(23 downto 16);
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when "1000" =>
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BYTE_ADDRESS <= "11";
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DMA_8BIT_WRITE_ENABLE <= '1';
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READDATA <= DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0)&DMA_MEMORY_DATA(7 downto 0);
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READDATA <= DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW&DMA_MEMORY_DATA_LOW;
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DMA_WRITE_DATA <= x"000000"&WRITEDATA(31 downto 24);
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when "1111" =>
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DMA_32BIT_WRITE_ENABLE <= '1';
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Add shadow hardware regs hack as in zpu