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