HardwareSPI.h

/*
  HardwareSPI.h - Hardware SPI interface for Arduino
  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"
 
#define SPI_HAS_TRANSACTION
 
namespace arduino {
 
typedef enum {
  SPI_MODE0 = 0,
  SPI_MODE1 = 1,
  SPI_MODE2 = 2,
  SPI_MODE3 = 3,
} SPIMode;
 
// Platforms should define SPI_HAS_PERIPHERAL_MODE if SPI peripheral
// mode is supported, to allow applications to check whether peripheral
// mode is available or not.
typedef enum {
  SPI_CONTROLLER = 0,
  SPI_PERIPHERAL = 1,
} SPIBusMode;
 
 
class SPISettings {
  public:
  SPISettings(uint32_t clock, BitOrder bitOrder, SPIMode dataMode, SPIBusMode busMode = SPI_CONTROLLER) {
    if (__builtin_constant_p(clock)) {
      init_AlwaysInline(clock, bitOrder, dataMode, busMode);
    } else {
      init_MightInline(clock, bitOrder, dataMode, busMode);
    }
  }
 
  SPISettings(uint32_t clock, BitOrder bitOrder, int dataMode, SPIBusMode busMode = SPI_CONTROLLER) {
    if (__builtin_constant_p(clock)) {
      init_AlwaysInline(clock, bitOrder, (SPIMode)dataMode, busMode);
    } else {
      init_MightInline(clock, bitOrder, (SPIMode)dataMode, busMode);
    }
  }
 
  // 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, SPI_CONTROLLER); }
 
  bool operator==(const SPISettings& rhs) const
  {
    if ((this->clockFreq == rhs.clockFreq) &&
        (this->bitOrder == rhs.bitOrder) &&
        (this->dataMode == rhs.dataMode) &&
        (this->busMode == rhs.busMode)) {
      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);
  }
  SPIBusMode getBusMode() const {
    return busMode;
  }
 
  private:
  void init_MightInline(uint32_t clock, BitOrder bitOrder, SPIMode dataMode, SPIBusMode busMode) {
    init_AlwaysInline(clock, bitOrder, dataMode, busMode);
  }
 
  // Core developer MUST use an helper function in beginTransaction() to use this data
  void init_AlwaysInline(uint32_t clock, BitOrder bitOrder, SPIMode dataMode, SPIBusMode busMode) __attribute__((__always_inline__)) {
    this->clockFreq = clock;
    this->dataMode = dataMode;
    this->bitOrder = bitOrder;
    this->busMode = busMode;
  }
 
  uint32_t clockFreq;
  SPIMode dataMode;
  BitOrder bitOrder;
  SPIBusMode busMode;
 
  friend class HardwareSPI;
};
 
const SPISettings DEFAULT_SPI_SETTINGS = SPISettings();
 
class HardwareSPI
{
  public:
    virtual ~HardwareSPI() { }
 
    virtual uint8_t transfer(uint8_t data) = 0;
    virtual uint16_t transfer16(uint16_t data) = 0;
    virtual void transfer(void *buf, size_t count) = 0;
 
    // Transaction Functions
    virtual void usingInterrupt(int interruptNumber) = 0;
    virtual void notUsingInterrupt(int interruptNumber) = 0;
    virtual void beginTransaction(SPISettings settings) = 0;
    virtual void endTransaction(void) = 0;
 
    // SPI Configuration methods
    virtual void attachInterrupt() = 0;
    virtual void detachInterrupt() = 0;
 
    virtual void begin() = 0;
    virtual void end() = 0;
};
 
// Alias SPIClass to HardwareSPI since it's already the defacto standard for SPI class name
typedef HardwareSPI SPIClass;
 
}