From d32c18f17585d35d6cba8af63f58c7345168e319 Mon Sep 17 00:00:00 2001
From: Chris Bagwell <chris@cnpbagwell.com>
Date: Wed, 2 Nov 2022 21:01:06 -0500
Subject: [PATCH] Increase cycle count for unoptimized cortex-m0

Cortex-M0 doesn't have 32bitx32bit=64bit multiplication instructions
and can not use SCURVE use optimized path.

Increasing to actual cycle count of 544 to hopefully improve
stability of board as well as a form of documentation that people
should consider disabling SCURVE feqature until the code is optimized
for cortex-m0;

Stepper::calc_timer_interval() use of division is also been identified
as taking 126 cycles.
---
 Marlin/src/module/stepper.h | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/Marlin/src/module/stepper.h b/Marlin/src/module/stepper.h
index 5b634c52e476..1e6bed5e6cc1 100644
--- a/Marlin/src/module/stepper.h
+++ b/Marlin/src/module/stepper.h
@@ -76,18 +76,30 @@
   #define TIMER_READ_ADD_AND_STORE_CYCLES 34UL
 
   // The base ISR takes 792 cycles
-  #define ISR_BASE_CYCLES  792UL
+  #if defined(STM32G0B1xx)
+    #define ISR_BASE_CYCLES  928UL
+  #else
+    #define ISR_BASE_CYCLES  792UL
+  #endif
 
   // Linear advance base time is 64 cycles
   #if ENABLED(LIN_ADVANCE)
-    #define ISR_LA_BASE_CYCLES 64UL
+    #if defined(STM32G0B1xx)
+      #define ISR_LA_BASE_CYCLES 200UL
+    #else
+      #define ISR_LA_BASE_CYCLES 64UL
+    #endif
   #else
     #define ISR_LA_BASE_CYCLES 0UL
   #endif
 
   // S curve interpolation adds 40 cycles
   #if ENABLED(S_CURVE_ACCELERATION)
-    #define ISR_S_CURVE_CYCLES 40UL
+    #if defined(STM32G0B1xx)
+      #define ISR_S_CURVE_CYCLES 544UL
+    #else
+      #define ISR_S_CURVE_CYCLES 40UL
+    #endif
   #else
     #define ISR_S_CURVE_CYCLES 0UL
   #endif