forked from FastLED/FastLED
-
Notifications
You must be signed in to change notification settings - Fork 0
/
hsv2rgb.cpp
476 lines (400 loc) · 15.3 KB
/
hsv2rgb.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
#include <stdint.h>
#include "lib8tion.h"
#include "hsv2rgb.h"
// 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, 192);
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 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;
{
offset8 <<= 1;
asm volatile("");
offset8 <<= 1;
asm volatile("");
offset8 <<= 1;
}
uint8_t third = scale8( offset8, (256 / 3));
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 = K171 + third;
//uint8_t twothirds = (third << 1);
uint8_t twothirds = scale8( offset8, ((256 * 2) / 3));
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));
r = K171 - twothirds;
g = K171 + 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));
g = K171 - twothirds;
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 = K171 + 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 ) {
nscale8x3_video( r, g, b, sat);
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);
nscale8x3_video( r, g, b, val);
}
// 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]);
}
}