SD:

- optimize SPI usage 148% write speed (24kB/s -> 37kB/s) and 127% read speed (121kB/s -> 155kB/s) at 8MHz
 - add clock frequency as parameter for begin(csPin, frequency)
 - SD @80MHz write: 84kB/s read: 231kB/s

SPI add functions:
 - void write32(uint32_t data);
 - void write32(uint32_t data, bool msb);
 - void transferBytes(uint8_t * out, uint8_t * in, uint32_t size);

Adafruit_ILI9341:
 - code clean

libraries/SD/src/SD.cpp

@@ -326,13 +326,7 @@ boolean callback_rmdir(SdFile& parentDir, char *filePathComponent,
   return true;
 }
 
-
-
-/* Implementation of class used to create `SDCard` object. */
-
-
-
-boolean SDClass::begin(uint8_t csPin) {
+boolean SDClass::begin(uint8_t csPin, uint32_t sckRateID) {
   /*
 
     Performs the initialisation required by the sdfatlib library.
@@ -340,13 +334,11 @@ boolean SDClass::begin(uint8_t csPin) {
     Return true if initialization succeeds, false otherwise.
 
    */
-  return card.init(SPI_HALF_SPEED, csPin) &&
+  return card.init(sckRateID, csPin) &&
          volume.init(card) &&
          root.openRoot(volume);
 }
 
-
-
 // this little helper is used to traverse paths
 SdFile SDClass::getParentDir(const char *filepath, int *index) {
   // get parent directory

libraries/SD/src/SD.h

@@ -65,8 +65,8 @@ private:
 public:
   // This needs to be called to set up the connection to the SD card
   // before other methods are used.
-  boolean begin(uint8_t csPin = SD_CHIP_SELECT_PIN);
-  
+  boolean begin(uint8_t csPin = SD_CHIP_SELECT_PIN, uint32_t sckRateID = SPI_FULL_SPEED);
+
   // Open the specified file/directory with the supplied mode (e.g. read or
   // write, etc). Returns a File object for interacting with the file.
   // Note that currently only one file can be open at a time.

libraries/SD/src/utility/Sd2Card.cpp

@@ -33,9 +33,13 @@ static void spiSend(uint8_t b) {
   SPDR = b;
   while (!(SPSR & (1 << SPIF)))
     ;
+#else
+#ifdef ESP8266
+  SPI.write(b);
 #else
   SPI.transfer(b);
 #endif
+#endif
 }
 /** Receive a byte from the card */
 static  uint8_t spiRec(void) {
@@ -116,8 +120,14 @@ uint8_t Sd2Card::cardCommand(uint8_t cmd, uint32_t arg) {
   // send command
   spiSend(cmd | 0x40);
 
+#ifdef ESP8266
+  // send argument
+  SPI.write32(arg, true);
+#else
   // send argument
   for (int8_t s = 24; s >= 0; s -= 8) spiSend(arg >> s);
+#endif
+
 
   // send CRC
   uint8_t crc = 0xFF;
@@ -424,7 +434,14 @@ uint8_t Sd2Card::readData(uint32_t block,
   dst[n] = SPDR;
 
 #else  // OPTIMIZE_HARDWARE_SPI
+#ifdef ESP8266
+  // skip data before offset
+  SPI.transferBytes(NULL, NULL, offset_);
 
+  // transfer data
+  SPI.transferBytes(NULL, dst, count);
+
+#else
   // skip data before offset
   for (;offset_ < offset; offset_++) {
     spiRec();
@@ -433,6 +450,7 @@ uint8_t Sd2Card::readData(uint32_t block,
   for (uint16_t i = 0; i < count; i++) {
     dst[i] = spiRec();
   }
+#endif
 #endif  // OPTIMIZE_HARDWARE_SPI
 
   offset_ += count;
@@ -463,7 +481,11 @@ void Sd2Card::readEnd(void) {
     while (!(SPSR & (1 << SPIF)))
       ;
 #else  // OPTIMIZE_HARDWARE_SPI
+#ifdef ESP8266
+    SPI.transferBytes(NULL, NULL, (514-offset_));
+#else
     while (offset_++ < 514) spiRec();
+#endif
 #endif  // OPTIMIZE_HARDWARE_SPI
     chipSelectHigh();
     inBlock_ = 0;
@@ -479,7 +501,11 @@ uint8_t Sd2Card::readRegister(uint8_t cmd, void* buf) {
   }
   if (!waitStartBlock()) goto fail;
   // transfer data
+#ifdef ESP8266
+  SPI.transferBytes(NULL, dst, 16);
+#else
   for (uint16_t i = 0; i < 16; i++) dst[i] = spiRec();
+#endif
   spiRec();  // get first crc byte
   spiRec();  // get second crc byte
   chipSelectHigh();
@@ -646,13 +672,21 @@ uint8_t Sd2Card::writeData(uint8_t token, const uint8_t* src) {
 
 #else  // OPTIMIZE_HARDWARE_SPI
   spiSend(token);
+#ifdef ESP8266
+  // send argument
+  SPI.writeBytes((uint8_t *)src, 512);
+#else
   for (uint16_t i = 0; i < 512; i++) {
     spiSend(src[i]);
   }
+#endif
 #endif  // OPTIMIZE_HARDWARE_SPI
+#ifdef ESP8266
+  SPI.write16(0xFFFF, true);
+#else
   spiSend(0xff);  // dummy crc
   spiSend(0xff);  // dummy crc
-
+#endif
   status_ = spiRec();
   if ((status_ & DATA_RES_MASK) != DATA_RES_ACCEPTED) {
     error(SD_CARD_ERROR_WRITE);