mirror of
https://github.com/DCC-EX/CommandStation-EX.git
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220 lines
7.1 KiB
C++
220 lines
7.1 KiB
C++
/*
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* © 2021, Chris Harlow, Neil McKechnie. All rights reserved.
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*
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* This file is part of CommandStation-EX
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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// CAUTION: the device dependent parts of this class are created in the .ini
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// using LCD_Implementation.h
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/* The strategy for drawing the screen is as follows.
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* 1) There are up to eight rows of text to be displayed.
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* 2) Blank rows of text are ignored.
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* 3) If there are more non-blank rows than screen lines,
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* then all of the rows are displayed, with the rest of the
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* screen being blank.
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* 4) If there are fewer non-blank rows than screen lines,
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* then a scrolling strategy is adopted so that, on each screen
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* refresh, a different subset of the rows is presented.
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* 5) On each entry into loop2(), a single operation is sent to the
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* screen; this may be a position command or a character for
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* display. This spreads the onerous work of updating the screen
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* and ensures that other loop() functions in the application are
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* not held up significantly. The exception to this is when
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* the loop2() function is called with force=true, where
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* a screen update is executed to completion. This is normally
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* only done during start-up.
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* The scroll mode is selected by defining SCROLLMODE as 0, 1 or 2
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* in the config.h.
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* #define SCROLLMODE 0 is scroll continuous (fill screen if poss),
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* #define SCROLLMODE 1 is by page (alternate between pages),
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* #define SCROLLMODE 2 is by row (move up 1 row at a time).
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*/
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#include "Display.h"
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// Constructor - allocates device driver.
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Display::Display(DisplayDevice *deviceDriver) {
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_deviceDriver = deviceDriver;
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// Get device dimensions in characters (e.g. 16x2).
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numScreenColumns = _deviceDriver->getNumCols();
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numScreenRows = _deviceDriver->getNumRows();
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for (uint8_t row = 0; row < MAX_CHARACTER_ROWS; row++)
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rowBuffer[row][0] = '\0';
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addDisplay(0); // Add this display as display number 0
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};
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void Display::begin() {
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_deviceDriver->begin();
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_deviceDriver->clearNative();
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}
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void Display::_clear() {
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_deviceDriver->clearNative();
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for (uint8_t row = 0; row < MAX_CHARACTER_ROWS; row++)
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rowBuffer[row][0] = '\0';
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}
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void Display::_setRow(uint8_t line) {
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hotRow = line;
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hotCol = 0;
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rowBuffer[hotRow][0] = '\0'; // Clear existing text
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}
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size_t Display::_write(uint8_t b) {
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if (hotRow >= MAX_CHARACTER_ROWS || hotCol >= MAX_CHARACTER_COLS) return -1;
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rowBuffer[hotRow][hotCol] = b;
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hotCol++;
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rowBuffer[hotRow][hotCol] = '\0';
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return 1;
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}
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// Refresh screen completely (will block until complete). Used
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// during start-up.
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void Display::_refresh() {
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loop2(true);
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}
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// On normal loop entries, loop will only make one output request on each
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// entry, to avoid blocking while waiting for the I2C.
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void Display::_displayLoop() {
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// If output device is busy, don't do anything on this loop
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// This avoids blocking while waiting for the device to complete.
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if (!_deviceDriver->isBusy()) loop2(false);
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}
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Display *Display::loop2(bool force) {
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unsigned long currentMillis = millis();
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if (!force) {
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// See if we're in the time between updates
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if ((currentMillis - lastScrollTime) < DISPLAY_SCROLL_TIME)
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return NULL;
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} else {
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// force full screen update from the beginning.
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rowFirst = 0;
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rowCurrent = 0;
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bufferPointer = 0;
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noMoreRowsToDisplay = false;
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slot = 0;
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}
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do {
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if (bufferPointer == 0) {
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// Search for non-blank row
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while (!noMoreRowsToDisplay) {
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if (!isCurrentRowBlank()) break;
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moveToNextRow();
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if (rowCurrent == rowFirst) noMoreRowsToDisplay = true;
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}
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if (noMoreRowsToDisplay) {
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// No non-blank lines left, so draw blank line
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buffer[0] = '\0';
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} else {
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// Non-blank line found, so copy it (including terminator)
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for (uint8_t i = 0; i <= MAX_CHARACTER_COLS; i++)
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buffer[i] = rowBuffer[rowCurrent][i];
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}
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_deviceDriver->setRowNative(slot); // Set position for display
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charIndex = 0;
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bufferPointer = &buffer[0];
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} else {
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// Write next character, or a space to erase current position.
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char ch = *bufferPointer;
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if (ch) {
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_deviceDriver->writeNative(ch);
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bufferPointer++;
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} else {
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_deviceDriver->writeNative(' ');
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}
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if (++charIndex >= MAX_CHARACTER_COLS) {
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// Screen slot completed, move to next nonblank row
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bufferPointer = 0;
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for (;;) {
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moveToNextRow();
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if (rowCurrent == rowFirst) {
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noMoreRowsToDisplay = true;
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break;
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}
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if (!isCurrentRowBlank()) break;
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}
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// Move to next screen slot, if available
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slot++;
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if (slot >= numScreenRows) {
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// Last slot on screen written, so get ready for next screen update.
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#if SCROLLMODE==0
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// Scrollmode 0 scrolls continuously. If the rows fit on the screen,
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// then restart at row 0, but otherwise continue with the row
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// after the last one displayed.
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if (countNonBlankRows() <= numScreenRows)
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rowCurrent = 0;
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rowFirst = rowCurrent;
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#elif SCROLLMODE==1
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// Scrollmode 1 scrolls by page, so if the last page has just completed then
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// next time restart with row 0.
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if (noMoreRowsToDisplay)
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rowFirst = rowCurrent = 0;
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#else
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// Scrollmode 2 scrolls by row. If the rows don't fit on the screen,
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// then start one row further on next time. If they do fit, then
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// show them in order and start next page at row 0.
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if (countNonBlankRows() <= numScreenRows) {
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rowFirst = rowCurrent = 0;
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} else {
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// Find first non-blank row after the previous first row
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rowCurrent = rowFirst;
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do {
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moveToNextRow();
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} while (isCurrentRowBlank());
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rowFirst = rowCurrent;
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}
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#endif
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noMoreRowsToDisplay = false;
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slot = 0;
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lastScrollTime = currentMillis;
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return NULL;
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}
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}
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}
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} while (force);
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return NULL;
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}
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bool Display::isCurrentRowBlank() {
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return (rowBuffer[rowCurrent][0] == '\0');
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}
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void Display::moveToNextRow() {
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// Skip blank rows
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if (++rowCurrent >= MAX_CHARACTER_ROWS)
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rowCurrent = 0;
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}
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uint8_t Display::countNonBlankRows() {
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uint8_t count = 0;
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for (uint8_t rowNumber=0; rowNumber<MAX_CHARACTER_ROWS; rowNumber++) {
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if (rowBuffer[rowNumber][0] != '\0')
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count++;
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}
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return count;
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}
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