Slightly simpler writer, P becomes freeptr

[yule.git] / writer.v

diff --git a/writer.v b/writer.v
index 7ef47ffa6688fb9923cea00f31ccc815d656ff92..c53d89f21c0ccf6487f6c8d87e17ed4f8d014dc1 100644 (file)
--- a/writer.v
+++ b/writer.v
@@ -1,62 +1,54 @@
-`define STATE_WRITE_TYPE 3'd0
-`define STATE_WRITE1     3'd1
-`define STATE_WRITE2     3'd2
-`define STATE_WRITE3     3'd3
-`define STATE_WRITE4     3'd4
+`define STATE_START        2'b00
+`define STATE_WRITE1       2'b01
+`define STATE_WRITE2       2'b10
+`define STATE_INCREMENT    2'b11
 
-module WRITER (input clk, input clk_enable, output [7:0] uart_tx_byte, output reg uart_tx_signal = 0, input uart_is_transmitting, output reg finished = 0, input [15:0] result);
-   reg [2:0] state = `STATE_WRITE_TYPE;
-   reg [3:0] tx_hex = 0;
+module WRITER (input clk, input clk_enable, output reg [7:0] tx_byte, output reg tx_signal = 0, input tx_busy, output reg finished = 0, output [12:0] ram_addr, input [15:0] ram_do, input [12:0] freeptr);
+   reg [1:0] state = `STATE_START;
 
-   hex_to_ascii h2a (.hex(tx_hex), .ascii(uart_tx_byte));
+   reg [12:0] current_index;
 
-   always @ (posedge clk)
+   assign ram_addr = current_index;
+
+   always @ (posedge clk) begin
         if (clk_enable) begin
-               if(uart_tx_signal)
-                 uart_tx_signal <= 0;
+               if(tx_signal)
+                 tx_signal <= 0;
 
                case(state)
-                 `STATE_WRITE_TYPE: begin
-                        finished <= 0;
-                        if(!uart_is_transmitting && !uart_tx_signal) begin
-                               uart_tx_signal <= 1;
-                               tx_hex <= {1'b0, result[15:13]};
-                               state <= `STATE_WRITE1;
-                        end
+                 `STATE_START: begin
+                        current_index <= 4;
+                        state <= `STATE_WRITE1;
                  end
 
                  `STATE_WRITE1: begin
-                        if(!uart_is_transmitting && !uart_tx_signal) begin
-                               uart_tx_signal <= 1;
-                               tx_hex <= {3'b0, result[12]};
+                        if(!tx_busy && !tx_signal) begin
+                               tx_signal <= 1;
+                               tx_byte <= ram_do[15:8];
                                state <= `STATE_WRITE2;
                         end
                  end
 
                  `STATE_WRITE2: begin
-                        if(!uart_is_transmitting && !uart_tx_signal) begin
-                               uart_tx_signal <= 1;
-                               tx_hex <= result[11:8];
-                               state <= `STATE_WRITE3;
+                        if(!tx_busy && !tx_signal) begin
+                               tx_signal <= 1;
+                               tx_byte <= ram_do[7:0];
+                               state <= `STATE_INCREMENT;
                         end
                  end
 
-                 `STATE_WRITE3: begin
-                        if(!uart_is_transmitting && !uart_tx_signal) begin
-                               uart_tx_signal <= 1;
-                               tx_hex <= result[7:4];
-                               state <= `STATE_WRITE4;
-                        end
-                 end
-
-                 `STATE_WRITE4: begin
-                        if(!uart_is_transmitting && !uart_tx_signal) begin
-                               uart_tx_signal <= 1;
-                               tx_hex <= result[3:0];
+                 `STATE_INCREMENT: begin
+                        current_index <= current_index + 1;
+                        if(current_index >= freeptr) begin
                                finished <= 1;
-                               state <= `STATE_WRITE_TYPE;
+                               state <= `STATE_START;
+                        end else begin
+                               state <= `STATE_WRITE1;
                         end
                  end
-               endcase
-        end
+               endcase // case (state)
+        end // if (clk_enable)
+        else
+          finished <= 0;
+   end
 endmodule