diff options
Diffstat (limited to 'usrp2/gpmc/gpmc_to_fifo.v')
-rw-r--r-- | usrp2/gpmc/gpmc_to_fifo.v | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/usrp2/gpmc/gpmc_to_fifo.v b/usrp2/gpmc/gpmc_to_fifo.v new file mode 100644 index 000000000..5d499494f --- /dev/null +++ b/usrp2/gpmc/gpmc_to_fifo.v @@ -0,0 +1,58 @@ + +module gpmc_to_fifo + (input EM_CLK, input [15:0] EM_D, input [1:0] EM_NBE, + input EM_NCS, input EM_NWE, + + input fifo_clk, input fifo_rst, + output reg [17:0] data_o, output reg src_rdy_o, input dst_rdy_i, + + input [15:0] frame_len, input [15:0] fifo_space, output fifo_ready); + + // Synchronize the async control signals + reg [1:0] cs_del, we_del; + always @(posedge fifo_clk) + if(fifo_rst) + begin + cs_del <= 2'b11; + we_del <= 2'b11; + end + else + begin + cs_del <= { cs_del[0], EM_NCS }; + we_del <= { we_del[0], EM_NWE }; + end + + wire do_write = (~cs_del[0] & (we_del == 2'b10)); + wire first_write = (counter == 0); + wire last_write = ((counter+1) == frame_len); + + always @(posedge fifo_clk) + if(do_write) + begin + data_o[15:0] <= EM_D; + data_o[16] <= first_write; + data_o[17] <= last_write; + // no byte writes data_o[18] <= |EM_NBE; // mark half full if either is not enabled FIXME + end + + always @(posedge fifo_clk) + if(fifo_rst) + src_rdy_o <= 0; + else if(do_write) + src_rdy_o <= 1; + else + src_rdy_o <= 0; // Assume it was taken + + reg [10:0] counter; + always @(posedge fifo_clk) + if(fifo_rst) + counter <= 0; + else if(do_write) + if(last_write) + counter <= 0; + else + counter <= counter + 1; + + assign fifo_ready = first_write & (fifo_space > frame_len); + +endmodule // gpmc_to_fifo |