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Arduboy2
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any upper register is fine

This commit is contained in:
Josh Goebel 2017-04-18 20:59:10 -04:00
parent 36bbfa89ab
commit b246b8180f
1 changed files with 3 additions and 3 deletions
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6
src/Arduboy2.cpp
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@ -292,7 +292,7 @@ void Arduboy2Base::drawPixel(int16_t x, int16_t y, uint8_t color)
// bit = _BV((uint8_t)y % 8);
// the above math can also be rewritten more simply as;
// (y * WIDTH/8) & ~0b01111111 + (uint8_t)x;
// row_offset = (y * WIDTH/8) & ~0b01111111 + (uint8_t)x;
// which is what the below assembler does
asm volatile(
"mul %[width_offset],%[y]\n"
@ -311,9 +311,9 @@ void Arduboy2Base::drawPixel(int16_t x, int16_t y, uint8_t color)
[bit] "=r" (bit)
: [width_offset] "r" ((uint8_t)(WIDTH/8)),
[x] "r" ((uint8_t)x),
[y] "a" ((uint8_t)y), // upper register (ANDI)
[y] "d" ((uint8_t)y), // upper register (ANDI)
"z" (bitshift_left)
: "r1", "r0");
:);
if (color) {
sBuffer[row_offset] |= bit;