From bc5780463a8b1d41f59c1c6bb5403c27e091fdf5 Mon Sep 17 00:00:00 2001
From: Sandeep Mistry <s.mistry@arduino.cc>
Date: Fri, 22 Dec 2017 11:58:22 -0500
Subject: [PATCH] Add SPI.notUsingInterrupt(...)

---
 libraries/SPI/SPI.cpp | 20 ++++++++++++++++++++
 libraries/SPI/SPI.h   |  4 ++++
 2 files changed, 24 insertions(+)

diff --git a/libraries/SPI/SPI.cpp b/libraries/SPI/SPI.cpp
index 8afb8146c..8ce3873b2 100644
--- a/libraries/SPI/SPI.cpp
+++ b/libraries/SPI/SPI.cpp
@@ -112,6 +112,26 @@ void SPIClass::usingInterrupt(int interruptNumber)
     interrupts();
 }
 
+void SPIClass::notUsingInterrupt(int interruptNumber)
+{
+  if ((interruptNumber == NOT_AN_INTERRUPT) || (interruptNumber == EXTERNAL_INT_NMI))
+    return;
+
+  if (interruptMode & SPI_IMODE_GLOBAL)
+    return; // can't go back, as there is no reference count
+
+  uint8_t irestore = interruptsStatus();
+  noInterrupts();
+
+  interruptMask &= ~(1 << interruptNumber);
+
+  if (interruptMask == 0)
+    interruptMode = SPI_IMODE_NONE;
+
+  if (irestore)
+    interrupts();
+}
+
 void SPIClass::beginTransaction(SPISettings settings)
 {
   if (interruptMode != SPI_IMODE_NONE)
diff --git a/libraries/SPI/SPI.h b/libraries/SPI/SPI.h
index d119bf4ac..ff741bf5c 100644
--- a/libraries/SPI/SPI.h
+++ b/libraries/SPI/SPI.h
@@ -29,6 +29,9 @@
 //   - SPISetting(clock, bitOrder, dataMode)
 #define SPI_HAS_TRANSACTION 1
 
+// SPI_HAS_NOTUSINGINTERRUPT means that SPI has notUsingInterrupt() method
+#define SPI_HAS_NOTUSINGINTERRUPT 1
+
 #define SPI_MODE0 0x02
 #define SPI_MODE1 0x00
 #define SPI_MODE2 0x03
@@ -100,6 +103,7 @@ class SPIClass {
 
   // Transaction Functions
   void usingInterrupt(int interruptNumber);
+  void notUsingInterrupt(int interruptNumber);
   void beginTransaction(SPISettings settings);
   void endTransaction(void);