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Fix for random uninitialized data in display RAM for displays less th…
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…an 128 segments wide.

Bug was visible when scrolling.
TDB: allow drawing outside visible area to exploit full 128 horizontal resolution in hardware scrolling.
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@dok-net
dok-net committed Oct 7, 2020
1 parent 477579d commit afa1a93
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Showing 2 changed files with 39 additions and 43 deletions.
72 changes: 33 additions & 39 deletions Adafruit_SSD1306.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -462,7 +462,7 @@ void Adafruit_SSD1306::ssd1306_command(uint8_t c) {
bool Adafruit_SSD1306::begin(uint8_t vcs, uint8_t addr, bool reset,
bool periphBegin) {

if ((!buffer) && !(buffer = (uint8_t *)malloc(WIDTH * ((HEIGHT + 7) / 8))))
if ((!buffer) && !(buffer = (uint8_t *)malloc(SSD1306_SEGMENTS * ((HEIGHT + 7) / 8))))
return false;

clearDisplay();
Expand Down Expand Up @@ -631,16 +631,17 @@ void Adafruit_SSD1306::drawPixel(int16_t x, int16_t y, uint16_t color) {
y = HEIGHT - y - 1;
break;
}
if ((WIDTH == 64) && (HEIGHT == 48)) x += 32;
switch (color) {
case SSD1306_WHITE:
buffer[x + (y / 8) * WIDTH] |= (1 << (y & 7));
break;
case SSD1306_BLACK:
buffer[x + (y / 8) * WIDTH] &= ~(1 << (y & 7));
break;
case SSD1306_INVERSE:
buffer[x + (y / 8) * WIDTH] ^= (1 << (y & 7));
break;
case SSD1306_WHITE:
buffer[x + (y / 8) * SSD1306_SEGMENTS] |= (1 << (y & 7));
break;
case SSD1306_BLACK:
buffer[x + (y / 8) * SSD1306_SEGMENTS] &= ~(1 << (y & 7));
break;
case SSD1306_INVERSE:
buffer[x + (y / 8) * SSD1306_SEGMENTS] ^= (1 << (y & 7));
break;
}
}
}
Expand All @@ -653,7 +654,7 @@ void Adafruit_SSD1306::drawPixel(int16_t x, int16_t y, uint16_t color) {
commands as needed by one's own application.
*/
void Adafruit_SSD1306::clearDisplay(void) {
memset(buffer, 0, WIDTH * ((HEIGHT + 7) / 8));
memset(buffer, 0, SSD1306_SEGMENTS * ((HEIGHT + 7) / 8));
}

/*!
Expand Down Expand Up @@ -716,7 +717,9 @@ void Adafruit_SSD1306::drawFastHLineInternal(int16_t x, int16_t y, int16_t w,
w = (WIDTH - x);
}
if (w > 0) { // Proceed only if width is positive
uint8_t *pBuf = &buffer[(y / 8) * WIDTH + x], mask = 1 << (y & 7);
if ((WIDTH == 64) && (HEIGHT == 48)) x += 32;
uint8_t* pBuf = &buffer[x + (y / 8) * SSD1306_SEGMENTS];
uint8_t mask = 1 << (y & 7);
switch (color) {
case SSD1306_WHITE:
while (w--) {
Expand Down Expand Up @@ -802,7 +805,8 @@ void Adafruit_SSD1306::drawFastVLineInternal(int16_t x, int16_t __y,
// this display doesn't need ints for coordinates,
// use local byte registers for faster juggling
uint8_t y = __y, h = __h;
uint8_t *pBuf = &buffer[(y / 8) * WIDTH + x];
if ((WIDTH == 64) && (HEIGHT == 48)) x += 32;
uint8_t *pBuf = &buffer[x + (y / 8) * SSD1306_SEGMENTS];

// do the first partial byte, if necessary - this requires some masking
uint8_t mod = (y & 7);
Expand Down Expand Up @@ -830,7 +834,7 @@ void Adafruit_SSD1306::drawFastVLineInternal(int16_t x, int16_t __y,
*pBuf ^= mask;
break;
}
pBuf += WIDTH;
pBuf += SSD1306_SEGMENTS;
}

if (h >= mod) { // More to go?
Expand All @@ -842,15 +846,15 @@ void Adafruit_SSD1306::drawFastVLineInternal(int16_t x, int16_t __y,
// black/white write version with an extra comparison per loop
do {
*pBuf ^= 0xFF; // Invert byte
pBuf += WIDTH; // Advance pointer 8 rows
pBuf += SSD1306_SEGMENTS; // Advance pointer 8 rows
h -= 8; // Subtract 8 rows from height
} while (h >= 8);
} else {
// store a local value to work with
uint8_t val = (color != SSD1306_BLACK) ? 255 : 0;
do {
*pBuf = val; // Set byte
pBuf += WIDTH; // Advance pointer 8 rows
pBuf += SSD1306_SEGMENTS; // Advance pointer 8 rows
h -= 8; // Subtract 8 rows from height
} while (h >= 8);
}
Expand Down Expand Up @@ -911,7 +915,8 @@ bool Adafruit_SSD1306::getPixel(int16_t x, int16_t y) {
y = HEIGHT - y - 1;
break;
}
return (buffer[x + (y / 8) * WIDTH] & (1 << (y & 7)));
if ((WIDTH == 64) && (HEIGHT == 48)) x += 32;
return (buffer[x + (y / 8) * SSD1306_SEGMENTS] & (1 << (y & 7)));
}
return false; // Pixel out of bounds
}
Expand All @@ -934,27 +939,16 @@ uint8_t *Adafruit_SSD1306::getBuffer(void) { return buffer; }
*/
void Adafruit_SSD1306::display(void) {
TRANSACTION_START
if ((WIDTH != 64) || (HEIGHT != 48)) {
static const uint8_t PROGMEM dlist1a[] = {
SSD1306_PAGEADDR,
0, // Page start address
0xFF, // Page end (not really, but works here)
SSD1306_COLUMNADDR,
0 }; // Column start address
ssd1306_commandList(dlist1a, sizeof(dlist1a));
ssd1306_command1(WIDTH - 1); // Column end address
} else {
static const uint8_t PROGMEM dlist1b[] = {
SSD1306_PAGEADDR,
0 }; // Page start address
ssd1306_commandList(dlist1b, sizeof(dlist1b));
ssd1306_command1((HEIGHT / 8) - 1); // Page end address
static const uint8_t PROGMEM dlist2b[] = {
SSD1306_COLUMNADDR,
32 }; // Column start address
ssd1306_commandList(dlist2b, sizeof(dlist2b));
ssd1306_command1(32 + WIDTH - 1); // Column end address
}
static const uint8_t PROGMEM dlist1[] = {
SSD1306_PAGEADDR,
0 }; // Page start address
ssd1306_commandList(dlist1, sizeof(dlist1));
ssd1306_command1((HEIGHT + 7) / 8 - 1); // Page end address
static const uint8_t PROGMEM dlist2[] = {
SSD1306_COLUMNADDR,
0 }; // Column start address
ssd1306_commandList(dlist2, sizeof(dlist2));
ssd1306_command1(SSD1306_SEGMENTS - 1); // Column end address

#if defined(ESP8266)
// ESP8266 needs a periodic yield() call to avoid watchdog reset.
Expand All @@ -965,7 +959,7 @@ void Adafruit_SSD1306::display(void) {
// 32-byte transfer condition below.
yield();
#endif
uint16_t count = WIDTH * ((HEIGHT + 7) / 8);
uint16_t count = SSD1306_SEGMENTS * ((HEIGHT + 7) / 8);
uint8_t *ptr = buffer;
if (wire) { // I2C
wire->beginTransmission(i2caddr);
Expand Down
10 changes: 6 additions & 4 deletions Adafruit_SSD1306.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,8 @@ typedef uint32_t PortMask;
#define SSD1306_ACTIVATE_SCROLL 0x2F ///< Start scroll
#define SSD1306_SET_VERTICAL_SCROLL_AREA 0xA3 ///< Set scroll range

#define SSD1306_SEGMENTS 128 ///< See datasheet

// Deprecated size stuff for backwards compatibility with old sketches
#if defined SSD1306_128_64
#define SSD1306_LCDWIDTH 128 ///< DEPRECATED: width w/SSD1306_128_64 defined
Expand Down Expand Up @@ -151,11 +153,11 @@ class Adafruit_SSD1306 : public Adafruit_GFX {
bool reset = true, bool periphBegin = true);
void display(void);
void clearDisplay(void);
void invertDisplay(bool i);
virtual void invertDisplay(bool i) override;
void dim(bool dim);
void drawPixel(int16_t x, int16_t y, uint16_t color);
virtual void drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color);
virtual void drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color);
virtual void drawPixel(int16_t x, int16_t y, uint16_t color) override;
virtual void drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color) override;
virtual void drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color) override;
void startscrollright(uint8_t start, uint8_t stop);
void startscrollleft(uint8_t start, uint8_t stop);
void startscrolldiagright(uint8_t start, uint8_t stop);
Expand Down

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