From 0b1dbbd0e4b7ea468002c4d6dd8ab21550d2bf7f Mon Sep 17 00:00:00 2001
From: lady ada <limor@ladyada.net>
Date: Sat, 18 Jul 2020 14:18:07 -0400
Subject: [PATCH] add fast software spi

---
 Adafruit_SPIDevice.cpp | 93 ++++++++++++++++++++++++++++++++++++------
 Adafruit_SPIDevice.h   | 25 ++++++++++++
 2 files changed, 105 insertions(+), 13 deletions(-)

diff --git a/Adafruit_SPIDevice.cpp b/Adafruit_SPIDevice.cpp
index 02c1b4e..cb26b24 100644
--- a/Adafruit_SPIDevice.cpp
+++ b/Adafruit_SPIDevice.cpp
@@ -46,6 +46,22 @@ Adafruit_SPIDevice::Adafruit_SPIDevice(int8_t cspin, int8_t sckpin,
   _sck = sckpin;
   _miso = misopin;
   _mosi = mosipin;
+
+#ifdef BUSIO_USE_FAST_PINIO
+  csPort = (BusIO_PortReg *)portOutputRegister(digitalPinToPort(cspin));
+  csPinMask = digitalPinToBitMask(cspin);
+  if (mosipin != -1) {
+    mosiPort = (BusIO_PortReg *)portOutputRegister(digitalPinToPort(mosipin));
+    mosiPinMask = digitalPinToBitMask(mosipin);
+  }
+  if (misopin != -1) {
+    misoPort = (BusIO_PortReg *)portInputRegister(digitalPinToPort(misopin));
+    misoPinMask = digitalPinToBitMask(misopin);
+  }
+  clkPort = (BusIO_PortReg *)portOutputRegister(digitalPinToPort(sckpin));
+  clkPinMask = digitalPinToBitMask(sckpin);
+#endif
+
   _freq = freq;
   _dataOrder = dataOrder;
   _dataMode = dataMode;
@@ -125,38 +141,89 @@ void Adafruit_SPIDevice::transfer(uint8_t *buffer, size_t len) {
       reply <<= 1;
       if (_dataMode == SPI_MODE0 || _dataMode == SPI_MODE2) {
         if (_mosi != -1) {
+#ifdef BUSIO_USE_FAST_PINIO
           digitalWrite(_mosi, send & (1 << b));
+#else
+          if (send & (1 << b))
+            *mosiPort |= mosiPinMask;
+          else
+            *mosiPort &= ~mosiPinMask;
+#endif
         }
+
+#ifdef BUSIO_USE_FAST_PINIO
+        *clkPort |= clkPinMask; // Clock high
+#else
         digitalWrite(_sck, HIGH);
-        if ((_miso != -1) && digitalRead(_miso)) {
-          reply |= 1;
+#endif
+
+        if (_miso != -1) {
+#ifdef BUSIO_USE_FAST_PINIO
+          if (*misoPort & misoPinMask) {
+#else
+          if (digitalRead(_miso)) {
+#endif
+            reply |= 1;
+          }
         }
+
+#ifdef BUSIO_USE_FAST_PINIO
+        *clkPort &= ~clkPinMask; // Clock low
+#else
         digitalWrite(_sck, LOW);
+#endif
       }
       if (_dataMode == SPI_MODE1 || _dataMode == SPI_MODE3) {
+
+#ifdef BUSIO_USE_FAST_PINIO
+        *clkPort |= clkPinMask; // Clock high
+#else
         digitalWrite(_sck, HIGH);
+#endif
+
         if (_mosi != -1) {
+#ifdef BUSIO_USE_FAST_PINIO
           digitalWrite(_mosi, send & (1 << b));
+#else
+          if (send & (1 << b))
+            *mosiPort |= mosiPinMask;
+          else
+            *mosiPort &= ~mosiPinMask;
+#endif
         }
+
+#ifdef BUSIO_USE_FAST_PINIO
+        *clkPort &= ~clkPinMask; // Clock low
+#else
         digitalWrite(_sck, LOW);
-        if ((_miso != -1) && digitalRead(_miso)) {
-          reply |= 1;
+#endif
+
+        if (_miso != -1) {
+#ifdef BUSIO_USE_FAST_PINIO
+          if (*misoPort & misoPinMask) {
+#else
+          if (digitalRead(_miso)) {
+#endif
+            reply |= 1;
+          }
         }
       }
     }
 
     // Serial.print(" : 0x"); Serial.print(reply, HEX);
-    if (_dataOrder == SPI_BITORDER_LSBFIRST) {
-      // LSB is rare, if it happens we'll just flip the bits around for them
-      uint8_t temp = 0;
-      for (uint8_t b = 0; b < 8; b++) {
-        temp |= ((reply >> b) & 0x1) << (7 - b);
+    if (_miso != -1) {
+      if (_dataOrder == SPI_BITORDER_LSBFIRST) {
+        // LSB is rare, if it happens we'll just flip the bits around for them
+        uint8_t temp = 0;
+        for (uint8_t b = 0; b < 8; b++) {
+          temp |= ((reply >> b) & 0x1) << (7 - b);
+        }
+        reply = temp;
       }
-      reply = temp;
-    }
-    // Serial.print(" -> "); Serial.println(reply, HEX);
+      // Serial.print(" -> "); Serial.println(reply, HEX);
 
-    buffer[i] = reply;
+      buffer[i] = reply;
+    }
   }
   return;
 }
diff --git a/Adafruit_SPIDevice.h b/Adafruit_SPIDevice.h
index 58e6167..565befc 100644
--- a/Adafruit_SPIDevice.h
+++ b/Adafruit_SPIDevice.h
@@ -29,6 +29,27 @@ typedef enum _BitOrder {
 #define SPI_BITORDER_LSBFIRST LSBFIRST
 #endif
 
+#if defined(__AVR__) || defined(TEENSYDUINO)
+typedef volatile uint8_t BusIO_PortReg;
+typedef uint8_t BusIO_PortMask;
+#define BUSIO_USE_FAST_PINIO
+
+#elif defined(ESP8266) || defined(ESP32) || defined(__SAM3X8E__) ||            \
+    defined(ARDUINO_ARCH_SAMD)
+typedef volatile uint32_t BusIO_PortReg;
+typedef uint32_t BusIO_PortMask;
+#define BUSIO_USE_FAST_PINIO
+
+#elif (defined(__arm__) || defined(ARDUINO_FEATHER52)) &&                      \
+    !defined(ARDUINO_ARCH_MBED)
+typedef volatile uint32_t BusIO_PortReg;
+typedef uint32_t BusIO_PortMask;
+#define BUSIO_USE_FAST_PINIO
+
+#else
+#undef BUSIO_USE_FAST_PINIO
+#endif
+
 /**! The class which defines how we will talk to this device over SPI **/
 class Adafruit_SPIDevice {
 public:
@@ -62,6 +83,10 @@ private:
   uint8_t _dataMode;
 
   int8_t _cs, _sck, _mosi, _miso;
+#ifdef BUSIO_USE_FAST_PINIO
+  BusIO_PortReg *mosiPort, *clkPort, *misoPort, *csPort;
+  BusIO_PortMask mosiPinMask, misoPinMask, clkPinMask, csPinMask;
+#endif
   bool _begun;
 };