From 7eaad3ce177b3d7a3cc218d6fcfd0c4ed0506139 Mon Sep 17 00:00:00 2001
From: Sylvain Lefebvre <sylvain.lefebvre@inria.fr>
Date: Sat, 13 Jul 2024 15:18:02 +0200
Subject: [PATCH] improved vga controller

---
 frameworks/boards/brot/board.json | 21 +++++++++++++++
 projects/common/vga.si            | 44 +++++++++++++++++++------------
 2 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/frameworks/boards/brot/board.json b/frameworks/boards/brot/board.json
index cea20448..36bae746 100644
--- a/frameworks/boards/brot/board.json
+++ b/frameworks/boards/brot/board.json
@@ -67,6 +67,27 @@
             {"cmd" : "dfu-suffix", "args" : "-v 1d50 -p 6146 -a build.dfu"},
             {"cmd" : "dfu-util", "args" : "-a 0 -D build.dfu"}
           ]
+        },
+        {
+          "name": "edalize_no_abc9",
+          "builder" : "edalize",
+          "description": "Build using Edalize",
+          "tool": "icestorm",
+          "tool_options": [
+            {
+                "icepack_options": ["-s"],
+                "yosys_synth_options": ["-dsp","-device u","-top top"],
+                "nextpnr_options": ["--up5k", "--freq 12", "--package sg48", "-r", "--opt-timing"],
+                "pnr": "next"
+            }
+          ],
+          "bitstream"  : "build.bin",
+          "constraints": [{"name": "brot.pcf", "file_type": "PCF"}],
+          "program": [
+            {"cmd" : "cp", "args" : "build.bin build.dfu"},
+            {"cmd" : "dfu-suffix", "args" : "-v 1d50 -p 6146 -a build.dfu"},
+            {"cmd" : "dfu-util", "args" : "-a 0 -D build.dfu"}
+          ]
         }
       ]
     }
diff --git a/projects/common/vga.si b/projects/common/vga.si
index 1df85ed1..84515061 100644
--- a/projects/common/vga.si
+++ b/projects/common/vga.si
@@ -86,31 +86,41 @@ $$VS_END   = V_FRT_PORCH + V_SYNCH
 $$VA_START = V_FRT_PORCH + V_SYNCH + V_BCK_PORCH
 $$V_END    = V_FRT_PORCH + V_SYNCH + V_BCK_PORCH + V_RES
 
-  uint12 xcount(0);
-  uint11 ycount(0);
+  int13  xcount(0);
+  int12  ycount(0);
 
-  uint12 pix_x     <:: (xcount - $HA_START$);
-  uint11 pix_y     <:: (ycount - $VA_START$);
+  uint1  active_h(0);
+  uint1  active_v(0);
 
-  uint1  active_h  <:: (xcount >= $HA_START$ && xcount < $H_END$);
-  uint1  active_v  <:: (ycount >= $VA_START$ && ycount < $VA_START + VGA_VA_END$);
+  always {
 
-  active           :=  active_h && active_v;
+    active_h  = xcount == 0                  ? 1
+              : xcount == $H_END-HA_START$   ? 0
+              : active_h;
+    active_v  = ycount == 0                  ? 1
+              : ycount == $VGA_VA_END$       ? 0
+              : active_v;
 
-  vga_hs           :=  ~((xcount >= $HS_START$ && xcount < $HS_END$));
-  vga_vs           :=  ~((ycount >= $VS_START$ && ycount < $VS_END$));
+    // __display("%d %d h:%b v:%b",xcount,ycount,active_h,active_v);
 
-  vblank           :=  (ycount < $VA_START$);
+    active = active_h && active_v;
 
-  always {
+    vga_x  = active_h ? xcount : 0;
+    vga_y  = active_v ? ycount : 0;
+
+    vga_hs = xcount == $HS_START-HA_START$ ? 0
+           : xcount == $HS_END-HA_START-1$ ? 1
+           : vga_hs;
+    vga_vs = ycount == $VS_START-VA_START$ ? 0
+           : ycount == $VS_END-VA_START-1$ ? 1
+           : vga_vs;
 
-    vga_x = active_h ? pix_x : 0;
-    vga_y = active_v ? pix_y : 0;
+    vblank = ycount[11,1]; // sign bit
 
-    if (xcount == $H_END-1$) {
-      xcount = 0;
-      if (ycount == $V_END-1$) {
-        ycount = 0;
+    if (xcount == $H_END-HA_START$) {
+      xcount = __signed($-HA_START+1$);
+      if (ycount == $V_END-VA_START$) {
+        ycount = __signed($-VA_START+1$);
       } else {
         ycount = ycount + 1;
 	    }