Optimize ESP8266 SPI performance

SdFat/src/FreeStack.h

@@ -23,7 +23,6 @@
  * \file
  * \brief FreeStack() function.
  */
- 
 #if defined(__AVR__) || defined(DOXYGEN)
 /** boundary between stack and heap. */
 extern char *__brkval;
@@ -35,7 +34,7 @@ extern char __bss_end;
 static int FreeStack() {
   char top;
   return __brkval ? &top - __brkval : &top - &__bss_end;
-} 
+}
 #elif defined(PLATFORM_ID)  // Particle board
 static int FreeStack() {
   return System.freeMemory();
@@ -46,7 +45,6 @@ static int FreeStack() {
   char top;
   return &top - reinterpret_cast<char*>(sbrk(0));
 }
-
 #else
 #warning FreeStack is not defined for this system.
 static int FreeStack() {

SdFat/src/SdFatConfig.h

@@ -189,6 +189,7 @@ const uint8_t SPI_SCK_INIT_DIVISOR = 128;
   || (defined(__arm__) && defined(CORE_TEENSY))\
   || defined(__STM32F1__)\
   || defined(PLATFORM_ID)\
+  || defined(ESP8266)\
   || defined(DOXYGEN)
 // Use custom fast implementation.
 #define SD_HAS_CUSTOM_SPI 1

SdFat/src/SdSpiCard/SdSpi.h

@@ -206,16 +206,12 @@ class SdSpiLib {
    *
    * \return Zero for no error or nonzero error code.
    */
-#if defined(PLATFORM_ID) && USE_SPI_LIB_DMA
-  uint8_t receive(uint8_t* buf, size_t n);
-#else  // defined(PLATFORM_ID) && USE_SPI_LIB_DMA
   uint8_t receive(uint8_t* buf, size_t n) {
     for (size_t i = 0; i < n; i++) {
       buf[i] = SPI.transfer(0XFF);
     }
     return 0;
   }
-#endif  // defined(PLATFORM_ID) && USE_SPI_LIB_DMA
   /** Send a byte.
    *
    * \param[in] b Byte to send
@@ -228,15 +224,11 @@ class SdSpiLib {
    * \param[in] buf Buffer for data to be sent.
    * \param[in] n Number of bytes to send.
    */
-#if defined(PLATFORM_ID) && USE_SPI_LIB_DMA
-  void send(const uint8_t* buf , size_t n);
-#else  // defined(PLATFORM_ID) && USE_SPI_LIB_DMA
   void send(const uint8_t* buf , size_t n) {
     for (size_t i = 0; i < n; i++) {
       SPI.transfer(buf[i]);
     }
   }
-#endif  // defined(PLATFORM_ID) && USE_SPI_LIB_DMA
 };
 //------------------------------------------------------------------------------
 #if SD_SPI_CONFIGURATION > 1 || defined(DOXYGEN)

SdFat/src/SdSpiCard/SdSpiESP8266.cpp

@@ -0,0 +1,101 @@
+/* Arduino SdSpi Library
+ * Copyright (C) 2016 by William Greiman
+ *
+ * STM32F1 code for Maple and Maple Mini support, 2015 by Victor Perez
+ *
+ * This file is part of the Arduino SdSpi Library
+ *
+ * This Library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with the Arduino SdSpi Library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+#if defined(ESP8266)
+#include "SdSpi.h"
+//------------------------------------------------------------------------------
+/** Initialize the SPI bus.
+ *
+ * \param[in] chipSelectPin SD card chip select pin.
+ */
+void SdSpi::begin(uint8_t chipSelectPin) {
+  pinMode(chipSelectPin, OUTPUT);
+  digitalWrite(chipSelectPin, HIGH);
+  SPI.begin();
+}
+//------------------------------------------------------------------------------
+/** Set SPI options for access to SD/SDHC cards.
+ *
+ * \param[in] divisor SCK clock divider relative to the system clock.
+ */
+void SdSpi::beginTransaction(uint8_t divisor) {
+#if ENABLE_SPI_TRANSACTIONS
+  // Note: ESP8266 beginTransaction does not protect for interrupts.
+  SPISettings settings(F_CPU/(divisor ? divisor : 1), MSBFIRST, SPI_MODE0);
+  SPI.beginTransaction(settings);
+#else  // ENABLE_SPI_TRANSACTIONS
+  // Note: ESP8266 beginTransaction is the same as following code.
+  SPI.setFrequency(F_CPU/(divisor ? divisor : 1));
+  SPI.setBitOrder(MSBFIRST);
+  SPI.setDataMode(SPI_MODE0);
+#endif  // ENABLE_SPI_TRANSACTIONS
+}
+//------------------------------------------------------------------------------
+void SdSpi::endTransaction() {
+#if ENABLE_SPI_TRANSACTIONS
+  // Note: endTransaction is an empty function on ESP8266.
+  SPI.endTransaction();
+#endif  // ENABLE_SPI_TRANSACTIONS
+}
+//------------------------------------------------------------------------------
+/** Receive a byte.
+ *
+ * \return The byte.
+ */
+uint8_t SdSpi::receive() {
+  return SPI.transfer(0XFF);
+}
+//------------------------------------------------------------------------------
+/** Receive multiple bytes.
+ *
+ * \param[out] buf Buffer to receive the data.
+ * \param[in] n Number of bytes to receive.
+ *
+ * \return Zero for no error or nonzero error code.
+ */
+uint8_t SdSpi::receive(uint8_t* buf, size_t n) {
+  // Works without 32-bit alignment of buf.
+  SPI.transferBytes(0, buf, n);
+  return 0;
+}
+//------------------------------------------------------------------------------
+/** Send a byte.
+ *
+ * \param[in] b Byte to send
+ */
+void SdSpi::send(uint8_t b) {
+  SPI.transfer(b);
+}
+//------------------------------------------------------------------------------
+/** Send multiple bytes.
+ *
+ * \param[in] buf Buffer for data to be sent.
+ * \param[in] n Number of bytes to send.
+ */
+void SdSpi::send(const uint8_t* buf , size_t n) {
+  // Adjust to 32-bit alignmented.
+  while ((reinterpret_cast<uintptr_t>(buf) & 0X3) && n) {
+    SPI.transfer(*buf++);
+    n--;
+  }
+  SPI.transferBytes(const_cast<uint8_t*>(buf), 0, n);
+}
+#endif  // defined(ESP8266)