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optimize ssd1306_draw_vline

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This commit is contained in:
Olli Asikainen 2020-04-24 16:33:36 +03:00
parent bc979883c2
commit 15d224e417
1 changed files with 15 additions and 64 deletions
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77
extras/ssd1306/ssd1306.c
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@ -588,7 +588,7 @@ int ssd1306_draw_hline(const ssd1306_t *dev, uint8_t *fb, int8_t x, int8_t y, ui
int ssd1306_draw_vline(const ssd1306_t *dev, uint8_t *fb, int8_t x, int8_t y, uint8_t h, ssd1306_color_t color)
{
uint16_t index;
uint8_t mask, mod, t;
uint8_t fill, mask, mod;
// boundary check
if ((x >= dev->width) || (x < 0) || (y >= dev->height) || (y < 0))
@ -598,17 +598,15 @@ int ssd1306_draw_vline(const ssd1306_t *dev, uint8_t *fb, int8_t x, int8_t y, ui
if (y + h > dev->height)
h = dev->height - y;
t = h;
index = x + (y / 8) * dev->width;
do {
mod = y & 7;
if (mod) // partial line that does not fit into byte at top
{
// Magic from Adafruit
mod = 8 - mod;
static const uint8_t premask[8] = { 0x00, 0x80, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC, 0xFE };
mask = premask[mod];
if (t < mod)
mask &= (0xFF >> (mod - t));
fill = 8 - mod;
if (fill > h)
fill = h;
index = x + (y / 8) * dev->width;
mask = ((1 << fill) - 1) << mod;
switch (color) {
case OLED_COLOR_WHITE:
fb[index] |= mask;
@ -623,58 +621,11 @@ int ssd1306_draw_vline(const ssd1306_t *dev, uint8_t *fb, int8_t x, int8_t y, ui
break;
}
if (t < mod)
return 0;
t -= mod;
index += dev->width;
}
if (t >= 8) // byte aligned line at middle
{
switch (color) {
case OLED_COLOR_WHITE:
do {
fb[index] = 0xff;
index += dev->width;
t -= 8;
} while (t >= 8);
break;
case OLED_COLOR_BLACK:
do {
fb[index] = 0x00;
index += dev->width;
t -= 8;
} while (t >= 8);
break;
case OLED_COLOR_INVERT:
do {
fb[index] = ~fb[index];
index += dev->width;
t -= 8;
} while (t >= 8);
break;
default:
break;
}
}
if (t) // partial line at bottom
{
mod = t & 7;
static const uint8_t postmask[8] = { 0x00, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F };
mask = postmask[mod];
switch (color) {
case OLED_COLOR_WHITE:
fb[index] |= mask;
break;
case OLED_COLOR_BLACK:
fb[index] &= ~mask;
break;
case OLED_COLOR_INVERT:
fb[index] ^= mask;
break;
default:
break;
}
}
y += fill;
h -= fill;
} while(h > 0);
return 0;
}