From e6654a2dffe5594aca18396f7e25e5896037337a Mon Sep 17 00:00:00 2001
From: morgan <mc@m-labs.hk>
Date: Wed, 15 Jan 2025 15:14:49 +0800
Subject: [PATCH] frameline GW: update docs

---
 src/gateware/cxp_frame_pipeline.py | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/gateware/cxp_frame_pipeline.py b/src/gateware/cxp_frame_pipeline.py
index 943da60..0c52ef5 100644
--- a/src/gateware/cxp_frame_pipeline.py
+++ b/src/gateware/cxp_frame_pipeline.py
@@ -432,13 +432,17 @@ class Pixel_Gearbox(Module):
             # sink_dw * i > size * j > source_dw * k  
             # where i,k are postive integers and source_dw * k - sink_dw * (i-1) > 0
             # 
-            # For example size == 10
-            # 32 * 2 > 10 * (5) > 40 * 1
-            # 32 * 2 > 10 * (6) > 40 * 1
-            # 32 * 3 > 10 * (9) > 40 * 2
             stb_aligned = Signal()
             match size: 
                 case 10:
+                    # For example size == 10
+                    # 32 * 2 > 10 * (5) > 40 * 1
+                    # 32 * 2 > 10 * (6) > 40 * 1
+                    # 32 * 3 > 10 * (9) > 40 * 2
+                    # ...
+                    # 
+                    # the packing pattern for size == 10 repeat every 16 pixels
+                    # the remaining special case can be taken care off using modulo operation
                     stb_cases = {
                         5: stb_aligned.eq(1),
                         6: stb_aligned.eq(1),
@@ -598,8 +602,8 @@ class ROI(Module):
     ROI Engine. For each frame, accumulates pixels values within a
     rectangular region of interest, and reports the total.
     """
-    def __init__(self, pixel_4x, count_len):
-        assert count_len <= 31
+    def __init__(self, pixel_4x, count_width):
+        assert count_width <= 32
         assert len(pixel_4x) == 4
 
         self.cfg = Record([
@@ -611,7 +615,7 @@ class ROI(Module):
 
         self.out = Record([
             ("update", 1),
-            ("count", count_len),
+            ("count", count_width),
         ])
 
         # # #
@@ -624,7 +628,7 @@ class ROI(Module):
                 ("y_good", 1),
                 ("gray", len(pixel_4x[0].gray)),
                 ("stb", 1),
-                ("count", count_len),
+                ("count", count_width),
         ]))
         
 
@@ -737,7 +741,7 @@ class Frame_Deserializer(Module):
 
 class ROI_Pipeline(Module):
     # largest x/y pixel size supported by frame header are 24 bits
-    def __init__(self, res_width=24):
+    def __init__(self, res_width, count_width):
 
         # NOTE: csr need to stay outside since this module need to be cdr in the CXP_FRAME_Pipeline module
         # NOTE: TapGeo other than 1X-1Y are not supported
@@ -748,7 +752,7 @@ class ROI_Pipeline(Module):
         self.submodules.header_decoder = header_decoder = Frame_Header_Decoder()
         self.submodules.deserializer = deserializer = Frame_Deserializer(res_width)
 
-        self.submodules.roi = ROI(deserializer.pixel4x, 31)
+        self.submodules.roi = ROI(deserializer.pixel4x, count_width)
 
         self.comb += [
             deserializer.new_frame.eq(header_decoder.new_frame),