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-rw-r--r--control_lib/giantfifo.v209
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diff --git a/control_lib/giantfifo.v b/control_lib/giantfifo.v
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-
-
-
-module giantfifo
- #(parameter WIDTH=36)
- (input clk, input rst,
- input [WIDTH-1:0] datain,
- output [WIDTH-1:0] dataout,
- input read,
- input write,
- input clear,
- output full,
- output empty,
- output [15:0] space,
- output [15:0] occupied,
-
- // External RAM
- inout [17:0] RAM_D,
- output reg [18:0] RAM_A,
- output RAM_CE1n,
- output RAM_CENn,
- output reg RAM_CLK,
- output reg RAM_WEn,
- output RAM_OEn,
- output RAM_LDn
- );
-
- wire [4:0] path1_occ, path2_space;
- wire [35:0] path1_dat, path2_dat;
-
- shortfifo #(.WIDTH(WIDTH)) sf1
- (.clk(clk),.rst(rst),.clear(clear),
- .datain(datain),.write(write),.full(full),
- .dataout(path1_dat),.read(path1_read),.empty(path1_empty),
- .space(),.occupied(path1_occ) );
- wire path1_almost_empty = (path1_occ == 5'd1);
-
- shortfifo #(.WIDTH(WIDTH)) sf2
- (.clk(clk),.rst(rst),.clear(clear),
- .datain(path2_dat),.write(path2_write),.full(path2_full),
- .dataout(dataout),.read(read),.empty(empty),
- .space(path2_space),.occupied() );
- wire path2_almost_full = (path2_space == 5'd1);
-
- assign RAM_CE1n = 1'b0;
- assign RAM_CENn = 1'b0;
- always @(clk)
- RAM_CLK <= #2 clk;
- assign RAM_LDn = 1'b0;
-
- // State machine
- wire write_now, read_now, idle, phase;
- reg ram_full, ram_empty;
-
- reg [17:0] read_ptr, write_ptr;
- reg [2:0] zbt_state;
-
- localparam ZBT_IDLE = 0;
- localparam ZBT_WRITE_UPPER = 2;
- localparam ZBT_WRITE_LOWER = 3;
- localparam ZBT_READ_UPPER = 4;
- localparam ZBT_READ_LOWER = 5;
-
- wire can_write = ~ram_full & ~path1_empty;
- wire can_write_chain = can_write & ~path1_almost_empty;
-
- wire can_read = ~ram_empty & ~path2_full;
- wire can_read_chain = can_read & ~path2_almost_full;
-
- assign phase = zbt_state[0];
-
- reg [17:0] ram_occupied;
- wire ram_almost_empty = (write_ptr == (read_ptr+1'b1));
- wire ram_almost_full = ((write_ptr+1'b1) == read_ptr);
-
- always @(posedge clk)
- if(rst | clear)
- begin
- zbt_state <= ZBT_IDLE;
- write_ptr <= 0;
- read_ptr <= 0;
- ram_full <= 0;
- ram_empty <= 1;
- ram_occupied <= 0;
- end
- else
- case(zbt_state)
- ZBT_IDLE :
- if(can_read)
- zbt_state <= ZBT_READ_UPPER;
- else if(can_write)
- zbt_state <= ZBT_WRITE_UPPER;
-
- ZBT_WRITE_UPPER :
- begin
- zbt_state <= ZBT_WRITE_LOWER;
- ram_occupied <= ram_occupied + 1;
- ram_empty <= 0;
- if(ram_occupied == 18'd10)
- ram_full <= 1;
- end
- ZBT_WRITE_LOWER :
- begin
- write_ptr <= write_ptr + 1;
- if(can_read_chain)
- zbt_state <= ZBT_READ_UPPER;
- else if(can_write_chain)
- zbt_state <= ZBT_WRITE_UPPER;
- else
- zbt_state <= ZBT_IDLE;
- end
- ZBT_READ_UPPER :
- begin
- zbt_state <= ZBT_READ_LOWER;
- ram_occupied <= ram_occupied - 1;
- ram_full <= 0;
- if(ram_occupied == 18'd1)
- ram_empty <= 1;
- end
- ZBT_READ_LOWER :
- begin
- read_ptr <= read_ptr + 1;
- if(can_read_chain)
- zbt_state <= ZBT_READ_UPPER;
- else if(can_write_chain)
- zbt_state <= ZBT_WRITE_UPPER;
- else
- zbt_state <= ZBT_IDLE;
- end
- default :
- zbt_state <= ZBT_IDLE;
- endcase // case(zbt_state)
-
- // Need to generate RAM_WEn, RAM_OEn, RAM_D, RAM_A;
- assign path1_read = (zbt_state == ZBT_WRITE_LOWER);
- reg path2_write, delayed_read_upper, delayed_read_lower, delayed_write;
-
- always @(posedge clk)
- if(delayed_read_upper)
- path2_dat[35:18] <= RAM_D;
- always @(posedge clk)
- if(delayed_read_lower)
- path2_dat[17:0] <= RAM_D;
-
- always @(posedge clk)
- if(rst)
- begin
- delayed_read_upper <= 0;
- delayed_read_lower <= 0;
- path2_write <= 0;
- end
- else
- begin
- delayed_read_upper <= (zbt_state == ZBT_READ_LOWER);
- delayed_read_lower <= delayed_read_upper;
- path2_write <= delayed_read_lower;
- end
-
- reg [17:0] RAM_D_pre2, RAM_D_pre1, RAM_D_out;
-
- always @(posedge clk)
- RAM_D_pre2 <= phase ? path1_dat[17:0] : path1_dat[35:18];
-
- always @(posedge clk) RAM_D_pre1 <= RAM_D_pre2;
- always @(posedge clk) RAM_D_out <= RAM_D_pre1;
- reg wr_del_1, wr_del_2;
- always @(posedge clk)
- if(rst)
- begin
- wr_del_1 <= 0;
- wr_del_2 <= 0;
- delayed_write <= 0;
- end
- else
- begin
- delayed_write <= wr_del_2;
- wr_del_2 <= wr_del_1;
- wr_del_1 <= write_now;
- end
-
- reg delayed_read, rd_del_1, rd_del_2;
- always @(posedge clk)
- if(rst)
- begin
- rd_del_1 <= 0;
- rd_del_2 <= 0;
- delayed_read <= 0;
- end
- else
- begin
- delayed_read <= rd_del_2;
- rd_del_2 <= rd_del_1;
- rd_del_1 <= read_now;
- end
-
- assign RAM_D = delayed_write ? RAM_D_out : 18'bzzzzzzzzzzzzzzzzzz;
- assign write_now = (zbt_state == ZBT_WRITE_UPPER) || (zbt_state == ZBT_WRITE_LOWER);
- assign read_now = (zbt_state == ZBT_READ_UPPER) || (zbt_state == ZBT_READ_LOWER);
-
- always @(posedge clk)
- RAM_A <= write_now ? {write_ptr,phase} : {read_ptr,phase};
-
- always @(posedge clk)
- RAM_WEn <= ~write_now;
-
- assign RAM_OEn = ~delayed_read;
- assign RAM_OEn = 0;
-
-endmodule // giantfifo