Add SPI class abstraction

Author: facchinm

api/HardwareSPI.h

@@ -0,0 +1,126 @@
+/*
+  Copyright (c) 2018 Arduino LLC.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#pragma once
+
+#include "Common.h"
+#include <inttypes.h>
+#include "Stream.h"
+
+namespace arduino {
+
+typedef enum {
+  SPI_MODE0 = 0,
+  SPI_MODE1 = 1,
+  SPI_MODE2 = 2,
+  SPI_MODE3 = 3,
+} SPIMode;
+
+
+class SPISettings {
+  public:
+  SPISettings(uint32_t clock, BitOrder bitOrder, SPIMode dataMode) {
+    if (__builtin_constant_p(clock)) {
+      init_AlwaysInline(clock, bitOrder, dataMode);
+    } else {
+      init_MightInline(clock, bitOrder, dataMode);
+    }
+  }
+
+  SPISettings(uint32_t clock, BitOrder bitOrder, int dataMode) {
+    if (__builtin_constant_p(clock)) {
+      init_AlwaysInline(clock, bitOrder, (SPIMode)dataMode);
+    } else {
+      init_MightInline(clock, bitOrder, (SPIMode)dataMode);
+    }
+  }
+
+  // Default speed set to 4MHz, SPI mode set to MODE 0 and Bit order set to MSB first.
+  SPISettings() { init_AlwaysInline(4000000, MSBFIRST, SPI_MODE0); }
+
+  bool operator==(const SPISettings& rhs) const
+  {
+    if ((this->clockFreq == rhs.clockFreq) &&
+        (this->bitOrder == rhs.bitOrder) &&
+        (this->dataMode == rhs.dataMode)) {
+      return true;
+    }
+    return false;
+  }
+
+  bool operator!=(const SPISettings& rhs) const
+  {
+    return !(*this == rhs);
+  }
+
+  uint32_t getClockFreq() const {
+    return clockFreq;
+  }
+  SPIMode getDataMode() const {
+    return dataMode;
+  }
+  BitOrder getBitOrder() const {
+    return (bitOrder);
+  }
+
+  private:
+  void init_MightInline(uint32_t clock, BitOrder bitOrder, SPIMode dataMode) {
+    init_AlwaysInline(clock, bitOrder, dataMode);
+  }
+
+  // Core developer MUST use an helper function in beginTransaction() to use this data
+  void init_AlwaysInline(uint32_t clock, BitOrder bitOrder, SPIMode dataMode) __attribute__((__always_inline__)) {
+    this->clockFreq = clock;
+    this->dataMode = dataMode;
+    this->bitOrder = bitOrder;
+  }
+
+  uint32_t clockFreq;
+  SPIMode dataMode;
+  BitOrder bitOrder;
+
+  friend class HardwareSPI;
+};
+
+const SPISettings DEFAULT_SPI_SETTINGS = SPISettings();
+
+class HardwareSPI
+{
+  public:
+    virtual uint8_t transfer(uint8_t data);
+    virtual uint16_t transfer16(uint16_t data);
+    virtual void transfer(void *buf, size_t count);
+
+    // Transaction Functions
+    virtual void usingInterrupt(int interruptNumber);
+    virtual void notUsingInterrupt(int interruptNumber);
+    virtual void beginTransaction(SPISettings settings);
+    virtual void endTransaction(void);
+
+    // SPI Configuration methods
+    virtual void attachInterrupt();
+    virtual void detachInterrupt();
+
+    virtual void begin();
+    virtual void end();
+};
+
+// Alias SPIClass to HardwareSPI since it's already the defacto standard for SPI classe name
+typedef HardwareSPI SPIClass;
+
+}