MycilaDimmer.cpp

// SPDX-License-Identifier: MIT
/*
 * Copyright (C) 2023-2025 Mathieu Carbou
 */
#include <MycilaDimmer.h>
 
#define DIMMER_RESOLUTION 12
#define FIRING_DELAYS_LEN 200U
 
static const uint32_t FIRING_DELAY_MAX = (1 << DIMMER_RESOLUTION) - 1;
static const uint32_t FIRING_DELAYS_SCALE = (FIRING_DELAYS_LEN - 1U) * (1UL << (16 - DIMMER_RESOLUTION));
static const uint16_t FIRING_DELAYS[FIRING_DELAYS_LEN] = {
  0xffff, 0xe877, 0xe240, 0xddd9, 0xda51, 0xd74f, 0xd4aa, 0xd248, 0xd01a, 0xce16,
  0xcc34, 0xca6e, 0xc8c0, 0xc728, 0xc5a1, 0xc42b, 0xc2c3, 0xc168, 0xc019, 0xbed3,
  0xbd98, 0xbc65, 0xbb3b, 0xba17, 0xb8fb, 0xb7e5, 0xb6d5, 0xb5ca, 0xb4c5, 0xb3c4,
  0xb2c8, 0xb1d1, 0xb0dd, 0xafed, 0xaf01, 0xae18, 0xad33, 0xac51, 0xab71, 0xaa95,
  0xa9bb, 0xa8e3, 0xa80e, 0xa73b, 0xa66b, 0xa59c, 0xa4d0, 0xa406, 0xa33d, 0xa276,
  0xa1b1, 0xa0ed, 0xa02b, 0x9f6b, 0x9eac, 0x9dee, 0x9d32, 0x9c76, 0x9bbc, 0x9b04,
  0x9a4c, 0x9996, 0x98e0, 0x982b, 0x9778, 0x96c5, 0x9613, 0x9563, 0x94b2, 0x9403,
  0x9354, 0x92a6, 0x91f9, 0x914c, 0x90a0, 0x8ff5, 0x8f4a, 0x8ea0, 0x8df6, 0x8d4d,
  0x8ca4, 0x8bfb, 0x8b53, 0x8aab, 0x8a04, 0x895d, 0x88b6, 0x8810, 0x876a, 0x86c4,
  0x861e, 0x8579, 0x84d3, 0x842e, 0x8389, 0x82e4, 0x823f, 0x819b, 0x80f6, 0x8051,
  0x7fad, 0x7f08, 0x7e63, 0x7dbf, 0x7d1a, 0x7c75, 0x7bd0, 0x7b2b, 0x7a85, 0x79e0,
  0x793a, 0x7894, 0x77ee, 0x7748, 0x76a1, 0x75fa, 0x7553, 0x74ab, 0x7403, 0x735a,
  0x72b1, 0x7208, 0x715e, 0x70b4, 0x7009, 0x6f5e, 0x6eb2, 0x6e05, 0x6d58, 0x6caa,
  0x6bfb, 0x6b4c, 0x6a9b, 0x69eb, 0x6939, 0x6886, 0x67d3, 0x671e, 0x6668, 0x65b2,
  0x64fa, 0x6442, 0x6388, 0x62cc, 0x6210, 0x6152, 0x6093, 0x5fd3, 0x5f11, 0x5e4d,
  0x5d88, 0x5cc1, 0x5bf8, 0x5b2e, 0x5a62, 0x5993, 0x58c3, 0x57f0, 0x571b, 0x5643,
  0x5569, 0x548d, 0x53ad, 0x52cb, 0x51e6, 0x50fd, 0x5011, 0x4f21, 0x4e2d, 0x4d36,
  0x4c3a, 0x4b39, 0x4a34, 0x4929, 0x4819, 0x4703, 0x45e7, 0x44c3, 0x4399, 0x4266,
  0x412b, 0x3fe5, 0x3e96, 0x3d3b, 0x3bd3, 0x3a5d, 0x38d6, 0x373e, 0x3590, 0x33ca,
  0x31e8, 0x2fe4, 0x2db6, 0x2b54, 0x28af, 0x25ad, 0x2225, 0x1dbe, 0x1787, 0x0000
};
 
// =============================================================================
// Mycila::Dimmer
// =============================================================================
 
uint16_t Mycila::Dimmer::_lookupFiringDelay(float dutyCycle, uint16_t semiPeriod) {
  uint32_t duty = dutyCycle * FIRING_DELAY_MAX;
  uint32_t slot = duty * FIRING_DELAYS_SCALE + (FIRING_DELAYS_SCALE >> 1);
  uint32_t index = slot >> 16;
  uint32_t a = FIRING_DELAYS[index];
  uint32_t b = FIRING_DELAYS[index + 1];
  uint32_t delay = a - (((a - b) * (slot & 0xffff)) >> 16); // interpolate a b
  return (delay * semiPeriod) >> 16; // scale to period
}