Some old AVR projects
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#include <stdlib.h>
#include <stdint.h>
#include "colors.h"
#include "hsl.h"
// based on: https://github.com/lewisd32/avr-hsl2rgb
xrgb_t hsl2xrgb(const hsl_t cc)
{
// 0 .. 256*3
const uint16_t hh = (uint16_t) cc.h * 3;
const uint8_t hue_mod = hh % 256;
uint8_t r_temp, g_temp, b_temp;
if (hh < 256) {
r_temp = hue_mod ^ 255;
g_temp = hue_mod;
b_temp = 0;
} else if (hh < 512) {
r_temp = 0;
g_temp = hue_mod ^ 255;
b_temp = hue_mod;
} else if (hh < 768) {
r_temp = hue_mod;
g_temp = 0;
b_temp = hue_mod ^ 255;
} else {
r_temp = 0;
g_temp = 0;
b_temp = 0;
}
const uint8_t inverse_sat = (cc.s ^ 255);
xrgb_t rgb;
uint8_t t8;
uint16_t t16;
#ifdef HSL_LINEAR
const uint8_t bri = FADE_128[cc.l>>1];
#else
const uint8_t bri = cc.l;
#endif
t8 = r_temp;
t16 = t8 * cc.s + t8;
t16 = t16 + t8;
t8 = t16 >> 8;
t8 = t8 + inverse_sat;
t16 = t8 * bri;
t16 = t16 + t8;
t8 = t16 >> 8;
rgb.r = t8;
t8 = g_temp;
t16 = t8 * cc.s;
t16 = t16 + t8;
t8 = t16 >> 8;
t8 = t8 + inverse_sat;
t16 = t8 * bri;
t16 = t16 + t8;
t8 = t16 >> 8;
rgb.g = t8;
t8 = b_temp;
t16 = t8 * cc.s;
t16 = t16 + t8;
t8 = t16 >> 8;
t8 = t8 + inverse_sat;
t16 = t8 * bri;
t16 = t16 + t8;
t8 = t16 >> 8;
rgb.b = t8;
return rgb;
}