mirror of
https://github.com/MiSTer-devel/CDi_MiSTer.git
synced 2026-06-14 03:04:32 +00:00
d53c682fcc
- Changes based on findings of the CDIC_BlackBoxAnalyzer project
- Removed side channel for audio coding
- A real CDIC reads the audio coding always from RAM
- Removed the concept of the audio tick found in MAME
- A real CDIC performs audio playback asynchronous to the CD reading
- Seek time now 19 sectors
- Fixes audio glitch in "Help cutscene" in "Zelda - Wand of Gamelon"
"Remember, tools can only be used..."
- Fixes audio regression during "Hotel Mario" score screen
- Fixed spurious IRQ caused by sector data interrupt after reading stopped
- Should fix hang on shopkeeper cutscene in "Zelda - Wand of Gamelon"
(Cannot be reproduced or is very unlikely now)
61 lines
1.7 KiB
Systemverilog
61 lines
1.7 KiB
Systemverilog
`timescale 1 ns / 1 ns
|
|
|
|
module audiofifo (
|
|
input clk,
|
|
input reset,
|
|
audiostream.sink in,
|
|
audiostream.source out,
|
|
output nearly_full,
|
|
output nearly_empty
|
|
);
|
|
|
|
bit signed [15:0] mem[64];
|
|
bit [5:0] read_index_d;
|
|
bit [5:0] read_index_q;
|
|
bit [5:0] write_index;
|
|
bit [6:0] count;
|
|
|
|
// The memory introduces one cycle delay. This is an issue
|
|
// when the FIFO is empty. We want to avoid using the memory readout
|
|
// when reading from a value that is just written
|
|
bit indizes_equal_during_write_d;
|
|
bit indizes_equal_during_write_q;
|
|
|
|
assign out.write = count != 0 && !reset && !indizes_equal_during_write_q;
|
|
assign in.strobe = count < 60 && !reset && in.write;
|
|
|
|
// Always a minimum of 28 XA samples per block
|
|
// We go for 48 just to be safe
|
|
assign nearly_full = count >= 48;
|
|
assign nearly_empty = count <= 3;
|
|
|
|
always_comb begin
|
|
read_index_d = read_index_q;
|
|
if (out.strobe && out.write) begin
|
|
read_index_d = read_index_q + 1;
|
|
end
|
|
|
|
indizes_equal_during_write_d = write_index == read_index_d && in.write;
|
|
end
|
|
|
|
always_ff @(posedge clk) begin
|
|
if (in.strobe && !out.strobe) count <= count + 1;
|
|
if (!in.strobe && out.strobe && count != 0) count <= count - 1;
|
|
|
|
if (reset) begin
|
|
write_index <= 0;
|
|
read_index_q <= 0;
|
|
count <= 0;
|
|
end else begin
|
|
if (in.write && in.strobe) begin
|
|
mem[write_index] <= in.sample;
|
|
write_index <= write_index + 1;
|
|
end
|
|
|
|
out.sample <= mem[read_index_d];
|
|
read_index_q <= read_index_d;
|
|
indizes_equal_during_write_q <= indizes_equal_during_write_d;
|
|
end
|
|
end
|
|
endmodule
|