WIP: relocate pixel generation out of VGAOutputSubtarget

software/glasgow/applet/video/vga_output/__init__.py

@@ -38,7 +38,7 @@ def elaborate(self, platform):
 
 
 class VGAOutputSubtarget(Elaboratable):
-    def __init__(self, pads, h_front, h_sync, h_back, h_active, v_front, v_sync, v_back, v_active, pix_clk_freq):
+    def __init__(self, pads, h_front, h_sync, h_back, h_active, v_front, v_sync, v_back, v_active, pix_clk_freq, pix_gen):
         self.pads = pads
         self.h_front = h_front
         self.h_sync = h_sync
@@ -49,6 +49,7 @@ def __init__(self, pads, h_front, h_sync, h_back, h_active, v_front, v_sync, v_b
         self.v_back = v_back
         self.v_active, = v_active,
         self.pix_clk_freq = pix_clk_freq
+        self.pix_gen = pix_gen
 
         self.h_total = self.h_front + self.h_sync + self.h_back + self.h_active
         self.v_total = self.v_front + self.v_sync + self.v_back + self.v_active
@@ -121,10 +122,7 @@ def elaborate(self, platform):
                 output.b.eq(0),
             ]
 
-        # TODO: relocate out of the module
-        m.d.comb += \
-            Cat(self.pix.r, self.pix.g, self.pix.b) \
-                .eq(self.h_ctr[5:] + self.v_ctr[5:])
+        self.pix_gen(self, m)
 
         return m
 
@@ -188,6 +186,11 @@ def add_build_arguments(cls, parser, access):
             help="set vertical resolution to N line clocks (default: %(default)s)")
 
     def build(self, target, args, test_pattern=True):
+        # TODO: is a callback like this okay, or would a sub-class of VGAOutputSubtarget be preferred?
+        def pix_gen(t, m):
+            m.d.comb += Cat(t.pix.r, t.pix.g, t.pix.b) \
+                            .eq(t.h_ctr[5:] + t.v_ctr[5:])
+
         self.mux_interface = iface = target.multiplexer.claim_interface(self, args)
         subtarget = iface.add_subtarget(VGAOutputSubtarget(
             pads=iface.get_pads(args, pins=self.__pins),
@@ -200,6 +203,7 @@ def build(self, target, args, test_pattern=True):
             v_back=args.v_back,
             v_active=args.v_active,
             pix_clk_freq=args.pix_clk_freq * 1e6,
+            pix_gen=pix_gen,
         ))
         return subtarget