From 1091ec1deefa49a1868672d8fbd8dbb219ac6787 Mon Sep 17 00:00:00 2001
From: Martin Preuss <martin@aquamaniac.de>
Date: Sun, 20 Jul 2025 23:15:22 +0200
Subject: [PATCH] read CLK and DATA early.

---
 avr/modules/com2w/com2w0.asm | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/avr/modules/com2w/com2w0.asm b/avr/modules/com2w/com2w0.asm
index b9e5e04..24a3b28 100644
--- a/avr/modules/com2w/com2w0.asm
+++ b/avr/modules/com2w/com2w0.asm
@@ -181,6 +181,7 @@ com2w0DataSetLow:
 ; ---------------------------------------------------------------------------
 ; @routine com2w0ReadNextBit
 ;
+; @param r17 data from COM_DATAn_INPUT
 ; @clobbers r16, r17, r18, r20, r22
 
 com2w0ReadNextBit:
@@ -188,7 +189,6 @@ com2w0ReadNextBit:
 ;  rcall com2w0WaitForClockHighMulti5Us  ; (R20, R22)
 ;  brcc com2w0ReadNextBit_end
   ; clock is high now, read bit
-  inr r17, COM_DATA0_INPUT
   ; reset read timer (for leaving skipping mode)
   clr r16
   std Y+NET_IFACE_OFFS_READTIMER, r16
@@ -566,8 +566,11 @@ COM2W0_ClkChangeIsr:
   push r15
     in r15, SREG
     push r16
-      inr r16, COM_CLK0_INPUT                ; read clk state early
-      rcall COM2W0_HandleClockInterrupt
+      push r17
+        inr r16, COM_CLK0_INPUT                ; read clk state early
+        inr r17, COM_DATA0_INPUT               ; read data state early
+        rcall COM2W0_HandleClockInterrupt
+      pop r17
     pop r16
     out SREG, r15
   pop r15
@@ -580,6 +583,7 @@ COM2W0_ClkChangeIsr:
 ; @routine COM2W0_HandleClockInterrupt @global
 ;
 ; @param r16 data from COM_CLKn_INPUT
+; @param r17 data from COM_DATAn_INPUT
 ; @clobbers none
 
 COM2W0_HandleClockInterrupt:
@@ -609,20 +613,30 @@ COM2W0_HandleClockInterrupt:
 ; @routine com2w0ActOnClock
 ;
 ; @param r16 data from COM_CLKn_INPUT
+; @param r17 data from COM_DATAn_INPUT
 ; @clobbers r16 (r17, r18, X)
 
 com2w0ActOnClock:
   andi r16, (1<<COM_CLK0_PIN)
   brne com2w0ActOnClock_clockHigh
   ; clock low
-  ldd r17, Y+COM2W_IFACE_OFFS_MODE
-  cpi r17, COM2W_MODE_IDLE
-  brne com2w0ActOnClock_end
+  ldd r18, Y+COM2W_IFACE_OFFS_MODE
+  cpi r18, COM2W_MODE_IDLE
+  breq com2w0ActOnClock_startReading
+  cpi r18, COM2W_MODE_SKIPPING
+  breq com2w0ActOnClock_skipping
+  rjmp com2w0ActOnClock_end
+com2w0ActOnClock_skipping:
+;  ldd r18, Y+COM2W_IFACE_OFFS_MODECOUNTER
+;  cpi r18, COM2W_SKIPPING_MAXMODECOUNTER
+;  brcc com2w0ActOnClock_startReading
+  rjmp com2w0ActOnClock_end
+com2w0ActOnClock_startReading:
   rcall com2wStartReading           ; (r16, r17, X)
   rjmp com2w0ActOnClock_end
 com2w0ActOnClock_clockHigh:
-  ldd r17, Y+COM2W_IFACE_OFFS_MODE
-  cpi r17, COM2W_MODE_READING
+  ldd r18, Y+COM2W_IFACE_OFFS_MODE
+  cpi r18, COM2W_MODE_READING
   brne com2w0ActOnClock_end
 
   push r20