also enable reading from vga text memory

1 files changed, 8 insertions, 5 deletions

diff --git a/design/vga.v b/design/vga.v
index 05a5c60..e69907c 100644
--- a/design/vga.v
+++ b/design/vga.v
@@ -38,14 +38,13 @@
     */
    reg [15:0]  text_memory [1279 : 0];
 
-   /*
-    * Enable writes to text_memory using wishbone interface.
-    * (no reads for now)
-    */
+   /* Enable writes and reads of text_memory using wishbone interface. */
 
+   reg [15:0]  data_at_adr;
+   reg 	       outputting_data;
    reg 	       ack;
 
-   assign DAT_O = {16{powered_on}};
+   assign DAT_O = outputting_data ? data_at_adr : {16{powered_on}};
    assign ACK_O = ack;
    assign STALL_O = 1'b0;
 
@@ -58,6 +57,10 @@
 	 else
 	   powered_on <= DAT_I != 16'b0;
       end
+
+      outputting_data <= ADR_I < 1280;
+
+      data_at_adr <= text_memory[ADR_I];
    end
 
    /* Non-wishbone part - generate 640x480 60Hz VGA output */