From ec1d674da7182fd77894e32dd9a15225be606251 Mon Sep 17 00:00:00 2001
From: Neil McKechnie <neilmck999@gmail.com>
Date: Thu, 18 Feb 2021 16:00:00 +0000
Subject: [PATCH] Enhance OLED/LCD speed

Write one character or position command per loop entry so as not to hold up the loop.  Add support for SH1106 OLED as 132x64 size option.
---
 LCDDisplay.cpp   | 100 +++++++++++++++++++++++++++++++++--------------
 LCDDisplay.h     |   4 +-
 LCD_NONE.h       |   2 +-
 LCD_OLED.h       |  21 +++++++---
 config.example.h |   1 +
 5 files changed, 91 insertions(+), 37 deletions(-)

diff --git a/LCDDisplay.cpp b/LCDDisplay.cpp
index e031f10..ae5e245 100644
--- a/LCDDisplay.cpp
+++ b/LCDDisplay.cpp
@@ -43,37 +43,79 @@ size_t LCDDisplay::write(uint8_t b) {
     if (!lcdDisplay) return;
     lcdDisplay->loop2(false);
  }
- 
- LCDDisplay*  LCDDisplay::loop2(bool force) { 
-    if ((!force) && (millis() - lastScrollTime)< LCD_SCROLL_TIME) return NULL;
-    lastScrollTime=millis();
-    clearNative();
-    int rowFirst=nextFilledRow();
-    if (rowFirst<0)return NULL; // No filled rows
-    setRowNative(0);
-    writeNative(rowBuffer[rowFirst]);
-    for (int slot=1;slot<lcdRows;slot++) {
-      int rowNext=nextFilledRow();
-      if (rowNext==rowFirst){
-         // we have wrapped around and not filled the screen 
-         topRow=-1; // start again at first row next time.  
-         break; 
-      }
-      setRowNative(slot);
-      writeNative(rowBuffer[rowNext]);
-    } 
-    displayNative();   
-    return NULL; 
- }
 
- int LCDDisplay::nextFilledRow() {
-      for (int rx=1;rx<=MAX_LCD_ROWS;rx++) {
-          topRow++;
-          topRow %= MAX_LCD_ROWS;
-          if (rowBuffer[topRow][0]) return topRow; 
+LCDDisplay *LCDDisplay::loop2(bool force)
+{
+     static int rowFirst = -1;
+     static int rowNext = 0;
+     static int charIndex = 0;
+     static char buffer[MAX_LCD_COLS+1];
+     static char *bptr = 0;
+     static bool done = false;
+
+     unsigned long currentMillis = millis();
+
+     if ((!force) && (currentMillis - lastScrollTime) < LCD_SCROLL_TIME)
+          return NULL;
+
+     do {
+          if (bptr == 0) { 
+               // No pending write, so go and look for one.
+               if (!done) {
+                    if (rowFirst < 0) rowFirst = rowNext;
+                    // Skip blank rows
+                    while (rowBuffer[rowNext][0] == 0) {
+                         rowNext = (rowNext + 1) % MAX_LCD_ROWS;
+                         if (rowNext == rowFirst) {
+                              done = true;
+                              break;
+                         }
+                    }
+               }
+
+               if (!done) {
+                    // Non-blank line found, so copy it.
+                    strncpy(buffer, rowBuffer[rowNext], MAX_LCD_COLS);
+               } else
+                    buffer[0] = '\0'; // Empty line
+
+               setRowNative(slot);  // Set position for display
+               charIndex = 0; 
+               bptr = &buffer[0];
+
+          } else {
+
+               // Write one character, which will be a space if the string is exhausted.
+               char ch = *bptr;
+               if (ch) {
+                    writeNative(ch);
+                    bptr++;
+               } else
+                    writeNative(' ');
+
+               if (++charIndex >= MAX_LCD_COLS) {
+                    // Screen slot completed, move to next one
+                    slot++;
+                    bptr = 0;
+                    if (!done) {
+                         rowNext = (rowNext + 1) % MAX_LCD_ROWS;
+                         if (rowNext == rowFirst) done = true;
+                    }
+               }
+
+               if (slot >= lcdRows) {
+                    // Last slot done, reset ready for next update.
+                    slot = 0; 
+                    done = false;
+                    rowFirst = -1;
+                    lastScrollTime = currentMillis;
+                    return NULL;
+               }
           }
-      return -1; // No slots filled
- }
+     } while (force);
+
+     return NULL;
+}
 
   
    
diff --git a/LCDDisplay.h b/LCDDisplay.h
index 9abcca3..5735cdc 100644
--- a/LCDDisplay.h
+++ b/LCDDisplay.h
@@ -49,13 +49,15 @@ class LCDDisplay : public Print {
     void clearNative();
     void displayNative();
     void setRowNative(byte line); 
-    void writeNative(char * b);
+    void writeNative(char b);
   
    unsigned long lastScrollTime=0;
    int hotRow=0;
    int hotCol=0; 
    int topRow=0;
    int lcdRows;
+   int lcdCols;
+   int slot=0;
    void renderRow(byte row);
    char rowBuffer[MAX_LCD_ROWS][MAX_LCD_COLS+1];     
 };
diff --git a/LCD_NONE.h b/LCD_NONE.h
index 65e05e4..ddaac48 100644
--- a/LCD_NONE.h
+++ b/LCD_NONE.h
@@ -22,6 +22,6 @@
   void LCDDisplay::interfake(int p1, int p2, int p3) {(void)p1; (void)p2; (void)p3;}   
   void LCDDisplay::setRowNative(byte row) { (void)row;} 
   void LCDDisplay::clearNative() {}
-  void LCDDisplay::writeNative(char * b){ (void)b;} //  
+  void LCDDisplay::writeNative(char b){ (void)b;} //  
   void LCDDisplay::displayNative(){}
   
diff --git a/LCD_OLED.h b/LCD_OLED.h
index a13a1cb..2a99aea 100644
--- a/LCD_OLED.h
+++ b/LCD_OLED.h
@@ -32,14 +32,21 @@ SSD1306AsciiWire LCDDriver;
     Wire.begin();
     for (byte address=0x3c; address<=0x3d; address++) {
       Wire.beginTransmission(address);
-      byte error = Wire.endTransmission();
+      byte error = Wire.endTransmission(true);
       if (!error) {
         // Device found
         DIAG(F("\nOLED display found at 0x%x"), address); 
         interfake(OLED_DRIVER,0);
-        LCDDriver.begin(lcdRows==32 ? &Adafruit128x32 : &Adafruit128x64, address);
+        const DevType *devType;
+        if (lcdCols == 132)
+          devType = &SH1106_128x64; // Actually 132x64 but treated as 128x64
+        else if (lcdCols == 128 && lcdRows == 8) 
+          devType = &Adafruit128x64;
+        else 
+          devType = &Adafruit128x32;
+        LCDDriver.begin(devType, address);
         lcdDisplay=this;
-        LCDDriver.setFont(System5x7);             // Normal 1:1 pixel scale
+        LCDDriver.setFont(System5x7);  // Normal 1:1 pixel scale, 8 bits high
         clear();
         return;  
       }
@@ -47,7 +54,7 @@ SSD1306AsciiWire LCDDriver;
     DIAG(F("\nOLED display not found\n"));
   }
 
-  void LCDDisplay::interfake(int p1, int p2, int p3) {(void)p1; lcdRows=p2/8; (void)p3;}   
+  void LCDDisplay::interfake(int p1, int p2, int p3) {lcdCols=p1; lcdRows=p2/8; (void)p3;}   
 
   void LCDDisplay::clearNative() {LCDDriver.clear();}
 
@@ -55,10 +62,12 @@ SSD1306AsciiWire LCDDriver;
     // Positions text write to start of row 1..n and clears previous text 
     int y=row;
     LCDDriver.setCursor(0, y); 
-    LCDDriver.clearToEOL();
+    //LCDDriver.clearToEOL();
   }
   
-  void LCDDisplay::writeNative(char * b){ LCDDriver.write(b); }    
+  void LCDDisplay::writeNative(char b) {
+    LCDDriver.write(b);
+  }
   
   void LCDDisplay::displayNative() {  }  
   
diff --git a/config.example.h b/config.example.h
index a20e6bb..a191bfc 100644
--- a/config.example.h
+++ b/config.example.h
@@ -102,6 +102,7 @@ The configuration file for DCC-EX Command Station
 
 //OR define OLED_DRIVER width,height in pixels (address auto detected)
 // 128x32 or 128x64 I2C SSD1306-based devices are supported.
+// Also 132x64 I2C SH1106 devices.
 // This will not work on a UNO due to memory constraints
 // #define OLED_DRIVER 128,32