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inactive segments robustness improvement

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* Avoid uint16 underflow in width() and height(): stop > start is possible, and means "inactive segment".

Without these checks, it was possible that width() and height() produce VERY large values due to underflow.
This commit is contained in:
Frank 2023-07-03 15:43:47 +02:00
parent eabd6f60ef
commit 406a254523
3 changed files with 5 additions and 4 deletions
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6
wled00/FX.h
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@ -507,9 +507,9 @@ typedef struct Segment {
inline bool hasRGB(void) const { return _isRGB; }
inline bool hasWhite(void) const { return _hasW; }
inline bool isCCT(void) const { return _isCCT; }
inline uint16_t width(void) const { return stop - start; } // segment width in physical pixels (length if 1D)
inline uint16_t height(void) const { return stopY - startY; } // segment height (if 2D) in physical pixels
inline uint16_t length(void) const { return width() * height(); } // segment length (count) in physical pixels
inline uint16_t width(void) const { return (stop > start) ? (stop - start) : 0; } // segment width in physical pixels (length if 1D)
inline uint16_t height(void) const { return (stopY > startY) ? (stopY - startY) : 0; } // segment height (if 2D) in physical pixels // softhack007: make sure its always > 0
inline uint16_t length(void) const { return width() * height(); } // segment length (count) in physical pixels
inline uint16_t groupLength(void) const { return grouping + spacing; }
inline uint8_t getLightCapabilities(void) const { return _capabilities; }

1
wled00/FX_2Dfcn.cpp
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@ -191,6 +191,7 @@ uint32_t WS2812FX::getPixelColorXY(uint16_t x, uint16_t y) {
uint16_t /*IRAM_ATTR*/ Segment::XY(uint16_t x, uint16_t y) {
uint16_t width = virtualWidth(); // segment width in logical pixels
uint16_t height = virtualHeight(); // segment height in logical pixels
if ((width == 0) || (height == 0)) return 0; // softhack007 avoid div/0
return (x%width) + (y%height) * width;
}

2
wled00/FX_fcn.cpp
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@ -729,7 +729,7 @@ uint32_t Segment::getPixelColor(int i)
i += start;
/* offset/phase */
i += offset;
if (i >= stop) i -= length();
if ((i >= stop) && (stop>0)) i -= length(); // avoids negative pixel index (stop = 0 is a possible value)
return strip.getPixelColor(i);
}