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#define FASTLED_INTERNAL
#include <stdint.h>
#include "FastLED.h"
FASTLED_NAMESPACE_BEGIN
// Functions to convert HSV colors to RGB colors.
//
// The basically fall into two groups: spectra, and rainbows.
// Spectra and rainbows are not the same thing. Wikipedia has a good
// illustration here
// http://upload.wikimedia.org/wikipedia/commons/f/f6/Prism_compare_rainbow_01.png
// from this article
// http://en.wikipedia.org/wiki/Rainbow#Number_of_colours_in_spectrum_or_rainbow
// that shows a 'spectrum' and a 'rainbow' side by side. Among other
// differences, you'll see that a 'rainbow' has much more yellow than
// a plain spectrum. "Classic" LED color washes are spectrum based, and
// usually show very little yellow.
//
// Wikipedia's page on HSV color space, with pseudocode for conversion
// to RGB color space
// http://en.wikipedia.org/wiki/HSL_and_HSV
// Note that their conversion algorithm, which is (naturally) very popular
// is in the "maximum brightness at any given hue" style, vs the "uniform
// brightness for all hues" style.
//
// You can't have both; either purple is the same brightness as red, e.g
// red = #FF0000 and purple = #800080 -> same "total light" output
// OR purple is 'as bright as it can be', e.g.
// red = #FF0000 and purple = #FF00FF -> purple is much brighter than red.
// The colorspace conversions here try to keep the apparent brightness
// constant even as the hue varies.
//
// Adafruit's "Wheel" function, discussed here
// http://forums.adafruit.com/viewtopic.php?f=47&t=22483
// is also of the "constant apparent brightness" variety.
//
// TODO: provide the 'maximum brightness no matter what' variation.
//
// See also some good, clear Arduino C code from Kasper Kamperman
// http://www.kasperkamperman.com/blog/arduino/arduino-programming-hsb-to-rgb/
// which in turn was was based on Windows C code from "nico80"
// http://www.codeproject.com/Articles/9207/An-HSB-RGBA-colour-picker
void hsv2rgb_raw_C (const struct CHSV & hsv, struct CRGB & rgb);
void hsv2rgb_raw_avr(const struct CHSV & hsv, struct CRGB & rgb);
#if defined(__AVR__) && !defined( LIB8_ATTINY )
void hsv2rgb_raw(const struct CHSV & hsv, struct CRGB & rgb)
{
hsv2rgb_raw_avr( hsv, rgb);
}
#else
void hsv2rgb_raw(const struct CHSV & hsv, struct CRGB & rgb)
{
hsv2rgb_raw_C( hsv, rgb);
}
#endif
#define APPLY_DIMMING(X) (X)
#define HSV_SECTION_6 (0x20)
#define HSV_SECTION_3 (0x40)
void hsv2rgb_raw_C (const struct CHSV & hsv, struct CRGB & rgb)
{
// Convert hue, saturation and brightness ( HSV/HSB ) to RGB
// "Dimming" is used on saturation and brightness to make
// the output more visually linear.
// Apply dimming curves
uint8_t value = APPLY_DIMMING( hsv.val);
uint8_t saturation = hsv.sat;
// The brightness floor is minimum number that all of
// R, G, and B will be set to.
uint8_t invsat = APPLY_DIMMING( 255 - saturation);
uint8_t brightness_floor = (value * invsat) / 256;
// The color amplitude is the maximum amount of R, G, and B
// that will be added on top of the brightness_floor to
// create the specific hue desired.
uint8_t color_amplitude = value - brightness_floor;
// Figure out which section of the hue wheel we're in,
// and how far offset we are withing that section
uint8_t section = hsv.hue / HSV_SECTION_3; // 0..2
uint8_t offset = hsv.hue % HSV_SECTION_3; // 0..63
uint8_t rampup = offset; // 0..63
uint8_t rampdown = (HSV_SECTION_3 - 1) - offset; // 63..0
// We now scale rampup and rampdown to a 0-255 range -- at least
// in theory, but here's where architecture-specific decsions
// come in to play:
// To scale them up to 0-255, we'd want to multiply by 4.
// But in the very next step, we multiply the ramps by other
// values and then divide the resulting product by 256.
// So which is faster?
// ((ramp * 4) * othervalue) / 256
// or
// ((ramp ) * othervalue) / 64
// It depends on your processor architecture.
// On 8-bit AVR, the "/ 256" is just a one-cycle register move,
// but the "/ 64" might be a multicycle shift process. So on AVR
// it's faster do multiply the ramp values by four, and then
// divide by 256.
// On ARM, the "/ 256" and "/ 64" are one cycle each, so it's
// faster to NOT multiply the ramp values by four, and just to
// divide the resulting product by 64 (instead of 256).
// Moral of the story: trust your profiler, not your insticts.
// Since there's an AVR assembly version elsewhere, we'll
// assume what we're on an architecture where any number of
// bit shifts has roughly the same cost, and we'll remove the
// redundant math at the source level:
// // scale up to 255 range
// //rampup *= 4; // 0..252
// //rampdown *= 4; // 0..252
// compute color-amplitude-scaled-down versions of rampup and rampdown
uint8_t rampup_amp_adj = (rampup * color_amplitude) / (256 / 4);
uint8_t rampdown_amp_adj = (rampdown * color_amplitude) / (256 / 4);
// add brightness_floor offset to everything
uint8_t rampup_adj_with_floor = rampup_amp_adj + brightness_floor;
uint8_t rampdown_adj_with_floor = rampdown_amp_adj + brightness_floor;
if( section ) {
if( section == 1) {
// section 1: 0x40..0x7F
rgb.r = brightness_floor;
rgb.g = rampdown_adj_with_floor;
rgb.b = rampup_adj_with_floor;
} else {
// section 2; 0x80..0xBF
rgb.r = rampup_adj_with_floor;
rgb.g = brightness_floor;
rgb.b = rampdown_adj_with_floor;
}
} else {
// section 0: 0x00..0x3F
rgb.r = rampdown_adj_with_floor;
rgb.g = rampup_adj_with_floor;
rgb.b = brightness_floor;
}
}
#if defined(__AVR__) && !defined( LIB8_ATTINY )
void hsv2rgb_raw_avr(const struct CHSV & hsv, struct CRGB & rgb)
{
uint8_t hue, saturation, value;
hue = hsv.hue;
saturation = hsv.sat;
value = hsv.val;
// Saturation more useful the other way around
saturation = 255 - saturation;
uint8_t invsat = APPLY_DIMMING( saturation );
// Apply dimming curves
value = APPLY_DIMMING( value );
// The brightness floor is minimum number that all of
// R, G, and B will be set to, which is value * invsat
uint8_t brightness_floor;
asm volatile(
"mul %[value], %[invsat] \n"
"mov %[brightness_floor], r1 \n"
: [brightness_floor] "=r" (brightness_floor)
: [value] "r" (value),
[invsat] "r" (invsat)
: "r0", "r1"
);
// The color amplitude is the maximum amount of R, G, and B
// that will be added on top of the brightness_floor to
// create the specific hue desired.
uint8_t color_amplitude = value - brightness_floor;
// Figure how far we are offset into the section of the
// color wheel that we're in
uint8_t offset = hsv.hue & (HSV_SECTION_3 - 1); // 0..63
uint8_t rampup = offset * 4; // 0..252
// compute color-amplitude-scaled-down versions of rampup and rampdown
uint8_t rampup_amp_adj;
uint8_t rampdown_amp_adj;
asm volatile(
"mul %[rampup], %[color_amplitude] \n"
"mov %[rampup_amp_adj], r1 \n"
"com %[rampup] \n"
"mul %[rampup], %[color_amplitude] \n"
"mov %[rampdown_amp_adj], r1 \n"
: [rampup_amp_adj] "=&r" (rampup_amp_adj),
[rampdown_amp_adj] "=&r" (rampdown_amp_adj),
[rampup] "+r" (rampup)
: [color_amplitude] "r" (color_amplitude)
: "r0", "r1"
);
// add brightness_floor offset to everything
uint8_t rampup_adj_with_floor = rampup_amp_adj + brightness_floor;
uint8_t rampdown_adj_with_floor = rampdown_amp_adj + brightness_floor;
// keep gcc from using "X" as the index register for storing
// results back in the return structure. AVR's X register can't
// do "std X+q, rnn", but the Y and Z registers can.
// if the pointer to 'rgb' is in X, gcc will add all kinds of crazy
// extra instructions. Simply killing X here seems to help it
// try Y or Z first.
asm volatile( "" : : : "r26", "r27" );
if( hue & 0x80 ) {
// section 2: 0x80..0xBF
rgb.r = rampup_adj_with_floor;
rgb.g = brightness_floor;
rgb.b = rampdown_adj_with_floor;
} else {
if( hue & 0x40) {
// section 1: 0x40..0x7F
rgb.r = brightness_floor;
rgb.g = rampdown_adj_with_floor;
rgb.b = rampup_adj_with_floor;
} else {
// section 0: 0x00..0x3F
rgb.r = rampdown_adj_with_floor;
rgb.g = rampup_adj_with_floor;
rgb.b = brightness_floor;
}
}
cleanup_R1();
}
// End of AVR asm implementation
#endif
void hsv2rgb_spectrum( const CHSV& hsv, CRGB& rgb)
{
CHSV hsv2(hsv);
hsv2.hue = scale8( hsv2.hue, 191);
hsv2rgb_raw(hsv2, rgb);
}
// Sometimes the compiler will do clever things to reduce
// code size that result in a net slowdown, if it thinks that
// a variable is not used in a certain location.
// This macro does its best to convince the compiler that
// the variable is used in this location, to help control
// code motion and de-duplication that would result in a slowdown.
#define FORCE_REFERENCE(var) asm volatile( "" : : "r" (var) )
#define K255 255
#define K171 171
#define K170 170
#define K85 85
void hsv2rgb_rainbow( const CHSV& hsv, CRGB& rgb)
{
// Yellow has a higher inherent brightness than
// any other color; 'pure' yellow is perceived to
// be 93% as bright as white. In order to make
// yellow appear the correct relative brightness,
// it has to be rendered brighter than all other
// colors.
// Level Y1 is a moderate boost, the default.
// Level Y2 is a strong boost.
const uint8_t Y1 = 1;
const uint8_t Y2 = 0;
// G2: Whether to divide all greens by two.
// Depends GREATLY on your particular LEDs
const uint8_t G2 = 0;
// Gscale: what to scale green down by.
// Depends GREATLY on your particular LEDs
const uint8_t Gscale = 0;
uint8_t hue = hsv.hue;
uint8_t sat = hsv.sat;
uint8_t val = hsv.val;
uint8_t offset = hue & 0x1F; // 0..31
// offset8 = offset * 8
uint8_t offset8 = offset;
{
#if defined(__AVR__)
// Left to its own devices, gcc turns "x <<= 3" into a loop
// It's much faster and smaller to just do three single-bit shifts
// So this business is to force that.
offset8 <<= 1;
asm volatile("");
offset8 <<= 1;
asm volatile("");
offset8 <<= 1;
#else
// On ARM and other non-AVR platforms, we just shift 3.
offset8 <<= 3;
#endif
}
uint8_t third = scale8( offset8, (256 / 3)); // max = 85
uint8_t r, g, b;
if( ! (hue & 0x80) ) {
// 0XX
if( ! (hue & 0x40) ) {
// 00X
//section 0-1
if( ! (hue & 0x20) ) {
// 000
//case 0: // R -> O
r = K255 - third;
g = third;
b = 0;
FORCE_REFERENCE(b);
} else {
// 001
//case 1: // O -> Y
if( Y1 ) {
r = K171;
g = K85 + third ;
b = 0;
FORCE_REFERENCE(b);
}
if( Y2 ) {
r = K170 + third;
//uint8_t twothirds = (third << 1);
uint8_t twothirds = scale8( offset8, ((256 * 2) / 3)); // max=170
g = K85 + twothirds;
b = 0;
FORCE_REFERENCE(b);
}
}
} else {
//01X
// section 2-3
if( ! (hue & 0x20) ) {
// 010
//case 2: // Y -> G
if( Y1 ) {
//uint8_t twothirds = (third << 1);
uint8_t twothirds = scale8( offset8, ((256 * 2) / 3)); // max=170
r = K171 - twothirds;
g = K170 + third;
b = 0;
FORCE_REFERENCE(b);
}
if( Y2 ) {
r = K255 - offset8;
g = K255;
b = 0;
FORCE_REFERENCE(b);
}
} else {
// 011
// case 3: // G -> A
r = 0;
FORCE_REFERENCE(r);
g = K255 - third;
b = third;
}
}
} else {
// section 4-7
// 1XX
if( ! (hue & 0x40) ) {
// 10X
if( ! ( hue & 0x20) ) {
// 100
//case 4: // A -> B
r = 0;
FORCE_REFERENCE(r);
//uint8_t twothirds = (third << 1);
uint8_t twothirds = scale8( offset8, ((256 * 2) / 3)); // max=170
g = K171 - twothirds; //K170?
b = K85 + twothirds;
} else {
// 101
//case 5: // B -> P
r = third;
g = 0;
FORCE_REFERENCE(g);
b = K255 - third;
}
} else {
if( ! (hue & 0x20) ) {
// 110
//case 6: // P -- K
r = K85 + third;
g = 0;
FORCE_REFERENCE(g);
b = K171 - third;
} else {
// 111
//case 7: // K -> R
r = K170 + third;
g = 0;
FORCE_REFERENCE(g);
b = K85 - third;
}
}
}
// This is one of the good places to scale the green down,
// although the client can scale green down as well.
if( G2 ) g = g >> 1;
if( Gscale ) g = scale8_video_LEAVING_R1_DIRTY( g, Gscale);
// Scale down colors if we're desaturated at all
// and add the brightness_floor to r, g, and b.
if( sat != 255 ) {
if( sat == 0) {
r = 255; b = 255; g = 255;
} else {
//nscale8x3_video( r, g, b, sat);
#if (FASTLED_SCALE8_FIXED==1)
if( r ) r = scale8_LEAVING_R1_DIRTY( r, sat);
if( g ) g = scale8_LEAVING_R1_DIRTY( g, sat);
if( b ) b = scale8_LEAVING_R1_DIRTY( b, sat);
#else
if( r ) r = scale8_LEAVING_R1_DIRTY( r, sat) + 1;
if( g ) g = scale8_LEAVING_R1_DIRTY( g, sat) + 1;
if( b ) b = scale8_LEAVING_R1_DIRTY( b, sat) + 1;
#endif
cleanup_R1();
uint8_t desat = 255 - sat;
desat = scale8( desat, desat);
uint8_t brightness_floor = desat;
r += brightness_floor;
g += brightness_floor;
b += brightness_floor;
}
}
// Now scale everything down if we're at value < 255.
if( val != 255 ) {
val = scale8_video_LEAVING_R1_DIRTY( val, val);
if( val == 0 ) {
r=0; g=0; b=0;
} else {
// nscale8x3_video( r, g, b, val);
#if (FASTLED_SCALE8_FIXED==1)
if( r ) r = scale8_LEAVING_R1_DIRTY( r, val);
if( g ) g = scale8_LEAVING_R1_DIRTY( g, val);
if( b ) b = scale8_LEAVING_R1_DIRTY( b, val);
#else
if( r ) r = scale8_LEAVING_R1_DIRTY( r, val) + 1;
if( g ) g = scale8_LEAVING_R1_DIRTY( g, val) + 1;
if( b ) b = scale8_LEAVING_R1_DIRTY( b, val) + 1;
#endif
cleanup_R1();
}
}
// Here we have the old AVR "missing std X+n" problem again
// It turns out that fixing it winds up costing more than
// not fixing it.
// To paraphrase Dr Bronner, profile! profile! profile!
//asm volatile( "" : : : "r26", "r27" );
//asm volatile (" movw r30, r26 \n" : : : "r30", "r31");
rgb.r = r;
rgb.g = g;
rgb.b = b;
}
void hsv2rgb_raw(const struct CHSV * phsv, struct CRGB * prgb, int numLeds) {
for(int i = 0; i < numLeds; i++) {
hsv2rgb_raw(phsv[i], prgb[i]);
}
}
void hsv2rgb_rainbow( const struct CHSV* phsv, struct CRGB * prgb, int numLeds) {
for(int i = 0; i < numLeds; i++) {
hsv2rgb_rainbow(phsv[i], prgb[i]);
}
}
void hsv2rgb_spectrum( const struct CHSV* phsv, struct CRGB * prgb, int numLeds) {
for(int i = 0; i < numLeds; i++) {
hsv2rgb_spectrum(phsv[i], prgb[i]);
}
}
#define FIXFRAC8(N,D) (((N)*256)/(D))
// This function is only an approximation, and it is not
// nearly as fast as the normal HSV-to-RGB conversion.
// See extended notes in the .h file.
CHSV rgb2hsv_approximate( const CRGB& rgb)
{
uint8_t r = rgb.r;
uint8_t g = rgb.g;
uint8_t b = rgb.b;
uint8_t h, s, v;
// find desaturation
uint8_t desat = 255;
if( r < desat) desat = r;
if( g < desat) desat = g;
if( b < desat) desat = b;
// remove saturation from all channels
r -= desat;
g -= desat;
b -= desat;
//Serial.print("desat="); Serial.print(desat); Serial.println("");
//uint8_t orig_desat = sqrt16( desat * 256);
//Serial.print("orig_desat="); Serial.print(orig_desat); Serial.println("");
// saturation is opposite of desaturation
s = 255 - desat;
//Serial.print("s.1="); Serial.print(s); Serial.println("");
if( s != 255 ) {
// undo 'dimming' of saturation
s = 255 - sqrt16( (255-s) * 256);
}
// without lib8tion: float ... ew ... sqrt... double ew, or rather, ew ^ 0.5
// if( s != 255 ) s = (255 - (256.0 * sqrt( (float)(255-s) / 256.0)));
//Serial.print("s.2="); Serial.print(s); Serial.println("");
// at least one channel is now zero
// if all three channels are zero, we had a
// shade of gray.
if( (r + g + b) == 0) {
// we pick hue zero for no special reason
return CHSV( 0, 0, 255 - s);
}
// scale all channels up to compensate for desaturation
if( s < 255) {
if( s == 0) s = 1;
uint32_t scaleup = 65535 / (s);
r = ((uint32_t)(r) * scaleup) / 256;
g = ((uint32_t)(g) * scaleup) / 256;
b = ((uint32_t)(b) * scaleup) / 256;
}
//Serial.print("r.2="); Serial.print(r); Serial.println("");
//Serial.print("g.2="); Serial.print(g); Serial.println("");
//Serial.print("b.2="); Serial.print(b); Serial.println("");
uint16_t total = r + g + b;
//Serial.print("total="); Serial.print(total); Serial.println("");
// scale all channels up to compensate for low values
if( total < 255) {
if( total == 0) total = 1;
uint32_t scaleup = 65535 / (total);
r = ((uint32_t)(r) * scaleup) / 256;
g = ((uint32_t)(g) * scaleup) / 256;
b = ((uint32_t)(b) * scaleup) / 256;
}
//Serial.print("r.3="); Serial.print(r); Serial.println("");
//Serial.print("g.3="); Serial.print(g); Serial.println("");
//Serial.print("b.3="); Serial.print(b); Serial.println("");
if( total > 255 ) {
v = 255;
} else {
v = qadd8(desat,total);
// undo 'dimming' of brightness
if( v != 255) v = sqrt16( v * 256);
// without lib8tion: float ... ew ... sqrt... double ew, or rather, ew ^ 0.5
// if( v != 255) v = (256.0 * sqrt( (float)(v) / 256.0));
}
//Serial.print("v="); Serial.print(v); Serial.println("");
#if 0
//#else
if( v != 255) {
// this part could probably use refinement/rethinking,
// (but it doesn't overflow & wrap anymore)
uint16_t s16;
s16 = (s * 256);
s16 /= v;
//Serial.print("s16="); Serial.print(s16); Serial.println("");
if( s16 < 256) {
s = s16;
} else {
s = 255; // clamp to prevent overflow
}
}
#endif
//Serial.print("s.3="); Serial.print(s); Serial.println("");
// since this wasn't a pure shade of gray,
// the interesting question is what hue is it
// start with which channel is highest
// (ties don't matter)
uint8_t highest = r;
if( g > highest) highest = g;
if( b > highest) highest = b;
if( highest == r ) {
// Red is highest.
// Hue could be Purple/Pink-Red,Red-Orange,Orange-Yellow
if( g == 0 ) {
// if green is zero, we're in Purple/Pink-Red
h = (HUE_PURPLE + HUE_PINK) / 2;
h += scale8( qsub8(r, 128), FIXFRAC8(48,128));
} else if ( (r - g) > g) {
// if R-G > G then we're in Red-Orange
h = HUE_RED;
h += scale8( g, FIXFRAC8(32,85));
} else {
// R-G < G, we're in Orange-Yellow
h = HUE_ORANGE;
h += scale8( qsub8((g - 85) + (171 - r), 4), FIXFRAC8(32,85)); //221
}
} else if ( highest == g) {
// Green is highest
// Hue could be Yellow-Green, Green-Aqua
if( b == 0) {
// if Blue is zero, we're in Yellow-Green
// G = 171..255
// R = 171.. 0
h = HUE_YELLOW;
uint8_t radj = scale8( qsub8(171,r), 47); //171..0 -> 0..171 -> 0..31
uint8_t gadj = scale8( qsub8(g,171), 96); //171..255 -> 0..84 -> 0..31;
uint8_t rgadj = radj + gadj;
uint8_t hueadv = rgadj / 2;
h += hueadv;
//h += scale8( qadd8( 4, qadd8((g - 128), (128 - r))),
// FIXFRAC8(32,255)); //
} else {
// if Blue is nonzero we're in Green-Aqua
if( (g-b) > b) {
h = HUE_GREEN;
h += scale8( b, FIXFRAC8(32,85));
} else {
h = HUE_AQUA;
h += scale8( qsub8(b, 85), FIXFRAC8(8,42));
}
}
} else /* highest == b */ {
// Blue is highest
// Hue could be Aqua/Blue-Blue, Blue-Purple, Purple-Pink
if( r == 0) {
// if red is zero, we're in Aqua/Blue-Blue
h = HUE_AQUA + ((HUE_BLUE - HUE_AQUA) / 4);
h += scale8( qsub8(b, 128), FIXFRAC8(24,128));
} else if ( (b-r) > r) {
// B-R > R, we're in Blue-Purple
h = HUE_BLUE;
h += scale8( r, FIXFRAC8(32,85));
} else {
// B-R < R, we're in Purple-Pink
h = HUE_PURPLE;
h += scale8( qsub8(r, 85), FIXFRAC8(32,85));
}
}
h += 1;
return CHSV( h, s, v);
}
// Examples that need work:
// 0,192,192
// 192,64,64
// 224,32,32
// 252,0,126
// 252,252,0
// 252,252,126
FASTLED_NAMESPACE_END