lcd: use writePattern for faster erases and lines.

The ESP8266 SPI implementation has a 'writePattern' function that
writes a repeating sequence (in this case a solid colour) to the SPI
port.  This fills up the FIFO and increases the bus utilisation.

Using this for clearing the screen cuts the demo run time from 4721 ms
to 3601 ms.  Also using this for the fast lines cuts the run time to
3424 ms.

Signed-off-by: Michael Hope <mlhx@google.com>

Adafruit_ST7735.cpp

@@ -490,34 +490,20 @@ void Adafruit_ST7735::pushColor(uint16_t color) {
 }
 
 void Adafruit_ST7735::drawPixel(int16_t x, int16_t y, uint16_t color) {
-
   if((x < 0) ||(x >= _width) || (y < 0) || (y >= _height)) return;
 
   setAddrWindow(x,y,x+1,y+1);
-
-  setRS(true);
-  setCS(false);
-
-  spiwrite16(color);
-
-  setCS(true);
+  writedata16(color);
 }
 
-
 void Adafruit_ST7735::drawFastVLine(int16_t x, int16_t y, int16_t h,
  uint16_t color) {
 
   // Rudimentary clipping
   if((x >= _width) || (y >= _height)) return;
   if((y+h-1) >= _height) h = _height-y;
   setAddrWindow(x, y, x, y+h-1);
-
-  setRS(true);
-  setCS(false);
-  while (h--) {
-    spiwrite16(color);
-  }
-  setCS(true);
+  writeColor(color, h);
 }
 
 
@@ -529,12 +515,7 @@ void Adafruit_ST7735::drawFastHLine(int16_t x, int16_t y, int16_t w,
   if((x+w-1) >= _width)  w = _width-x;
   setAddrWindow(x, y, x+w-1, y);
 
-  setRS(true);
-  setCS(false);
-  while (w--) {
-    spiwrite16(color);
-  }
-  setCS(true);
+  writeColor(color, w);
 }
 
 
@@ -544,6 +525,19 @@ void Adafruit_ST7735::fillScreen(uint16_t color) {
 }
 
 
+void Adafruit_ST7735::writeColor(uint16_t color, uint16_t count) {
+  setRS(true);
+  setCS(false);
+#if defined(ST7735_USE_HWSPI_WRITEPATTERN)
+  uint8_t pattern[] = { (uint8_t)(color >> 8), (uint8_t)(color >> 0) };
+  SPI.writePattern(pattern, sizeof(pattern), count);
+#else
+  for (; count != 0; count--) {
+    spiwrite16(color);
+  }
+#endif
+  setCS(true);
+}
 
 // fill a rectangle
 void Adafruit_ST7735::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,
@@ -555,15 +549,7 @@ void Adafruit_ST7735::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,
   if((y + h - 1) >= _height) h = _height - y;
 
   setAddrWindow(x, y, x+w-1, y+h-1);
-
-  setRS(true);
-  setCS(false);
-  for(y=h; y>0; y--) {
-    for(x=w; x>0; x--) {
-      spiwrite16(color);
-    }
-  }
-  setCS(true);
+  writeColor(color, w*h);
 }
 
 

Adafruit_ST7735.h

@@ -159,6 +159,7 @@ class Adafruit_ST7735 : public Adafruit_GFX {
            writecommand(uint8_t c),
            writedata(uint8_t d),
            writedata16(uint16_t d),
+           writeColor(uint16_t color, uint16_t count),
            setCS(bool level),
            setRS(bool level),
            commandList(const uint8_t *addr),
@@ -181,6 +182,7 @@ volatile uint8_t *dataport, *clkport, *csport, *rsport;
 #define ST7735_USE_GENERIC_IO
 #define ST7735_USE_HWSPI_ONLY
 #define ST7735_USE_HWSPI_WRITE16
+#define ST7735_USE_HWSPI_WRITEPATTERN
   uint8_t _cs, _rs, _rst, _sid, _sclk;
   uint8_t colstart, rowstart;
 #endif