52 lines
1.7 KiB
C
52 lines
1.7 KiB
C
/*
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* lightshow_format.h — Core data structures for show playback.
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*
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* All show data lives in PROGMEM (flash memory) to preserve the
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* Arduino Uno's 2KB of RAM. The read_* helpers copy values out of
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* PROGMEM so the rest of the code can work with them normally.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <avr/pgmspace.h>
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#include <stdint.h>
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// Show playback modes.
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#define SHOW_LOOP 0 // repeat the show indefinitely
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#define SHOW_SINGLE 1 // play once, then auto-advance to the next show
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// One step in a lightshow: a target color and the time to reach it.
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struct Step {
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uint8_t r, g, b; // Target RGB color (0–255 each)
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uint16_t duration_ms; // Milliseconds to fade from the previous color (0 = instant)
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};
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// Descriptor for one complete show.
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struct ShowDef {
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const Step* steps; // Pointer to a PROGMEM Step array
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uint16_t length; // Number of steps in the array
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uint8_t mode; // SHOW_LOOP or SHOW_SINGLE
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};
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// Read one Step from PROGMEM into a regular struct.
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// Direct pointer access does not work for PROGMEM on AVR — use this helper.
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inline Step read_step(const Step* ptr) {
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Step s;
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s.r = pgm_read_byte(&ptr->r);
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s.g = pgm_read_byte(&ptr->g);
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s.b = pgm_read_byte(&ptr->b);
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s.duration_ms = pgm_read_word(&ptr->duration_ms);
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return s;
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}
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// Read one ShowDef from a PROGMEM ShowDef array.
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// On AVR, pointers are 2 bytes wide, so pgm_read_word works for both fields.
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inline ShowDef read_show_def(const ShowDef* ptr) {
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ShowDef sd;
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sd.steps = (const Step*)pgm_read_word(&ptr->steps);
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sd.length = pgm_read_word(&ptr->length);
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sd.mode = pgm_read_byte(&ptr->mode);
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return sd;
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}
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