helpers.cpp

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#include "esphome/core/helpers.h"
 
#include "esphome/core/defines.h"
#include "esphome/core/hal.h"
#include "esphome/core/log.h"
#include "esphome/core/progmem.h"
#include "esphome/core/string_ref.h"
 
#include <strings.h>
#include <algorithm>
#include <cmath>
#include <cstdarg>
#include <cstdio>
#include <cstdlib>
#include <cstring>
 
#ifdef USE_ESP32
#include "esp_rom_crc.h"
#endif
 
namespace esphome {
 
#ifdef USE_ESP8266
std::string progmem_string(ProgmemStr str) {
  auto *src = reinterpret_cast<PGM_P>(str);
  std::string result(strlen_P(src), '\0');
  memcpy_P(result.data(), src, result.size());
  return result;
}
#endif
 
ESPHOME_LOG_TAG(TAG, "helpers");
 
__attribute__((noinline, cold)) void *callback_manager_grow(void *data, uint16_t size, uint16_t &capacity,
                                                            size_t elem_size) {
  ESPHOME_DEBUG_ASSERT(size < UINT16_MAX);
  uint16_t new_cap = size + 1;
  auto *new_data = ::operator new(new_cap * elem_size);
  if (data) {
    __builtin_memcpy(new_data, data, size * elem_size);
    ::operator delete(data);
  }
  capacity = new_cap;
  return new_data;
}
 
static const uint16_t CRC16_A001_LE_LUT_L[] = {0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
                                               0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440};
static const uint16_t CRC16_A001_LE_LUT_H[] = {0x0000, 0xcc01, 0xd801, 0x1400, 0xf001, 0x3c00, 0x2800, 0xe401,
                                               0xa001, 0x6c00, 0x7800, 0xb401, 0x5000, 0x9c01, 0x8801, 0x4400};
 
#ifndef USE_ESP32
static const uint16_t CRC16_8408_LE_LUT_L[] = {0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
                                               0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7};
static const uint16_t CRC16_8408_LE_LUT_H[] = {0x0000, 0x1081, 0x2102, 0x3183, 0x4204, 0x5285, 0x6306, 0x7387,
                                               0x8408, 0x9489, 0xa50a, 0xb58b, 0xc60c, 0xd68d, 0xe70e, 0xf78f};
#endif
 
#ifndef USE_ESP32
static const uint16_t CRC16_1021_BE_LUT_L[] = {0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
                                               0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef};
static const uint16_t CRC16_1021_BE_LUT_H[] = {0x0000, 0x1231, 0x2462, 0x3653, 0x48c4, 0x5af5, 0x6ca6, 0x7e97,
                                               0x9188, 0x83b9, 0xb5ea, 0xa7db, 0xd94c, 0xcb7d, 0xfd2e, 0xef1f};
#endif
 
// Mathematics
 
uint8_t crc8(const uint8_t *data, uint8_t len, uint8_t crc, uint8_t poly, bool msb_first) {
  while ((len--) != 0u) {
    uint8_t inbyte = *data++;
    if (msb_first) {
      // MSB first processing (for polynomials like 0x31, 0x07)
      crc ^= inbyte;
      for (uint8_t i = 8; i != 0u; i--) {
        if (crc & 0x80) {
          crc = (crc << 1) ^ poly;
        } else {
          crc <<= 1;
        }
      }
    } else {
      // LSB first processing (default for Dallas/Maxim 0x8C)
      for (uint8_t i = 8; i != 0u; i--) {
        bool mix = (crc ^ inbyte) & 0x01;
        crc >>= 1;
        if (mix)
          crc ^= poly;
        inbyte >>= 1;
      }
    }
  }
  return crc;
}
 
uint16_t crc16(const uint8_t *data, uint16_t len, uint16_t crc, uint16_t reverse_poly, bool refin, bool refout) {
#ifdef USE_ESP32
  if (reverse_poly == 0x8408) {
    crc = esp_rom_crc16_le(refin ? crc : (crc ^ 0xffff), data, len);
    return refout ? crc : (crc ^ 0xffff);
  }
#endif
  if (refin) {
    crc ^= 0xffff;
  }
#ifndef USE_ESP32
  if (reverse_poly == 0x8408) {
    while (len--) {
      uint8_t combo = crc ^ (uint8_t) *data++;
      crc = (crc >> 8) ^ CRC16_8408_LE_LUT_L[combo & 0x0F] ^ CRC16_8408_LE_LUT_H[combo >> 4];
    }
  } else
#endif
  {
    if (reverse_poly == 0xa001) {
      while (len--) {
        uint8_t combo = crc ^ (uint8_t) *data++;
        crc = (crc >> 8) ^ CRC16_A001_LE_LUT_L[combo & 0x0F] ^ CRC16_A001_LE_LUT_H[combo >> 4];
      }
    } else {
      while (len--) {
        crc ^= *data++;
        for (uint8_t i = 0; i < 8; i++) {
          if (crc & 0x0001) {
            crc = (crc >> 1) ^ reverse_poly;
          } else {
            crc >>= 1;
          }
        }
      }
    }
  }
  return refout ? (crc ^ 0xffff) : crc;
}
 
uint16_t crc16be(const uint8_t *data, uint16_t len, uint16_t crc, uint16_t poly, bool refin, bool refout) {
#ifdef USE_ESP32
  if (poly == 0x1021) {
    crc = esp_rom_crc16_be(refin ? crc : (crc ^ 0xffff), data, len);
    return refout ? crc : (crc ^ 0xffff);
  }
#endif
  if (refin) {
    crc ^= 0xffff;
  }
#ifndef USE_ESP32
  if (poly == 0x1021) {
    while (len--) {
      uint8_t combo = (crc >> 8) ^ *data++;
      crc = (crc << 8) ^ CRC16_1021_BE_LUT_L[combo & 0x0F] ^ CRC16_1021_BE_LUT_H[combo >> 4];
    }
  } else
#endif
  {
    while (len--) {
      crc ^= (((uint16_t) *data++) << 8);
      for (uint8_t i = 0; i < 8; i++) {
        if (crc & 0x8000) {
          crc = (crc << 1) ^ poly;
        } else {
          crc <<= 1;
        }
      }
    }
  }
  return refout ? (crc ^ 0xffff) : crc;
}
 
// FNV-1 hash - deprecated, use fnv1a_hash() for new code
uint32_t fnv1_hash(const char *str) {
  uint32_t hash = FNV1_OFFSET_BASIS;
  if (str) {
    while (*str) {
      hash *= FNV1_PRIME;
      hash ^= *str++;
    }
  }
  return hash;
}
 
// SplitMix32 — a fast, non-cryptographic PRNG from the SplitMix family
// (Steele et al., 2014). Uses a Weyl sequence with golden-ratio increment
// and the MurmurHash3 32-bit finalizer as output mixing function.
// Reference: https://doi.org/10.1145/2714064.2660195
// Test results: https://lemire.me/blog/2017/08/22/testing-non-cryptographic-random-number-generators-my-results/
// Seeded lazily from the platform's secure RNG via random_bytes().
// ESP8266 uses os_random() instead (defined in esp8266/helpers.cpp).
#ifndef USE_ESP8266
static uint32_t splitmix32_state;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
uint32_t random_uint32() {
  // State of 0 means unseeded. The state will wrap back to 0 after 2^32 calls,
  // triggering one extra random_bytes() call — an acceptable trade-off vs. adding
  // a separate bool flag (4 bytes BSS + branch on every call).
  if (splitmix32_state == 0) {
    random_bytes(reinterpret_cast<uint8_t *>(&splitmix32_state), sizeof(splitmix32_state));
    splitmix32_state |= 1;  // ensure non-zero seed
  }
  splitmix32_state += 0x9e3779b9u;
  uint32_t z = splitmix32_state;
  z = (z ^ (z >> 16)) * 0x85ebca6bu;
  z = (z ^ (z >> 13)) * 0xc2b2ae35u;
  return z ^ (z >> 16);
}
#endif
 
float random_float() { return static_cast<float>(random_uint32()) / static_cast<float>(UINT32_MAX); }
 
// Strings
 
bool str_equals_case_insensitive(const std::string &a, const std::string &b) {
  return strcasecmp(a.c_str(), b.c_str()) == 0;
}
bool str_equals_case_insensitive(StringRef a, StringRef b) {
  return a.size() == b.size() && strncasecmp(a.c_str(), b.c_str(), a.size()) == 0;
}
#if __cplusplus >= 202002L
bool str_startswith(const std::string &str, const std::string &start) { return str.starts_with(start); }
bool str_endswith(const std::string &str, const std::string &end) { return str.ends_with(end); }
#else
bool str_startswith(const std::string &str, const std::string &start) { return str.rfind(start, 0) == 0; }
bool str_endswith(const std::string &str, const std::string &end) {
  return str.rfind(end) == (str.size() - end.size());
}
#endif
 
bool str_endswith_ignore_case(const char *str, size_t str_len, const char *suffix, size_t suffix_len) {
  if (suffix_len > str_len)
    return false;
  return strncasecmp(str + str_len - suffix_len, suffix, suffix_len) == 0;
}
 
bool str_contains_ignore_case_fallback(const char *haystack, const char *needle) {
  const size_t needle_len = strlen(needle);
  if (needle_len == 0) {
    return true;
  }
  for (const char *p = haystack; *p != '\0'; p++) {
    if (strncasecmp(p, needle, needle_len) == 0) {
      return true;
    }
  }
  return false;
}
 
#ifdef USE_ESP8266
// _P mirror of str_contains_ignore_case_fallback above; host tests cover only the fallback,
// so keep the two bodies in sync.
bool str_contains_ignore_case_p(const char *haystack, PGM_P needle) {
  if (haystack == nullptr || needle == nullptr) {
    return false;
  }
  const size_t needle_len = strlen_P(needle);
  if (needle_len == 0) {
    return true;
  }
  for (const char *p = haystack; *p != '\0'; p++) {
    if (strncasecmp_P(p, needle, needle_len) == 0) {
      return true;
    }
  }
  return false;
}
#endif  // USE_ESP8266
 
char *str_sanitize_to(char *buffer, size_t buffer_size, const char *str) {
  if (buffer_size == 0) {
    return buffer;
  }
  size_t i = 0;
  while (*str && i < buffer_size - 1) {
    buffer[i++] = to_sanitized_char(*str++);
  }
  buffer[i] = '\0';
  return buffer;
}
 
size_t make_name_with_suffix_to(char *buffer, size_t buffer_size, const char *name, size_t name_len, char sep,
                                const char *suffix_ptr, size_t suffix_len) {
  size_t total_len = name_len + 1 + suffix_len;
 
  // Silently truncate if needed: prioritize keeping the full suffix
  if (total_len >= buffer_size) {
    // NOTE: This calculation could underflow if suffix_len >= buffer_size - 2,
    // but this is safe because this helper is only called with small suffixes:
    // MAC suffixes (6-12 bytes), ".local" (5 bytes), etc.
    name_len = buffer_size - suffix_len - 2;  // -2 for separator and null terminator
    total_len = name_len + 1 + suffix_len;
  }
 
  memcpy(buffer, name, name_len);
  buffer[name_len] = sep;
  memcpy(buffer + name_len + 1, suffix_ptr, suffix_len);
  buffer[total_len] = '\0';
  return total_len;
}
 
size_t truncate_name_to(char *buffer, size_t buffer_size, const char *name, size_t name_len, size_t keep_suffix_len) {
  if (buffer_size == 0) {
    return 0;
  }
  const size_t max_len = buffer_size - 1;
  if (name_len <= max_len) {
    memcpy(buffer, name, name_len);
    buffer[name_len] = '\0';
    return name_len;
  }
  if (keep_suffix_len > max_len) {
    keep_suffix_len = max_len;
  }
  const size_t head_len = max_len - keep_suffix_len;
  memcpy(buffer, name, head_len);
  memcpy(buffer + head_len, name + name_len - keep_suffix_len, keep_suffix_len);
  buffer[max_len] = '\0';
  return max_len;
}
 
// Parsing & formatting
 
// A plain decimal converts exactly with one division: the digits accumulate
// into an integer that stays below 2^24 and the fraction's scale is a power of
// ten up to 1e9 (2^9 * 5^9), so both convert to float exactly and IEEE division
// rounds the quotient correctly, the same result strtof produces.
static constexpr uint32_t PARSE_FLOAT_MANTISSA_LIMIT = 1000000;  // one more digit stays below 2^24
static constexpr uint32_t PARSE_FLOAT_MAX_FRACTION_DIGITS = 9;
 
optional<float> parse_float(const char *str) {
  const char *p = str;
  const bool negative = *p == '-';
  if (negative || *p == '+')
    p++;
  const char *digits = p;
  const char *dot = nullptr;
  uint32_t mantissa = 0;
  for (;; p++) {
    const uint32_t d = static_cast<unsigned char>(*p) - '0';
    if (d > 9) {
      if (*p == '.' && dot == nullptr) {
        dot = p;
        continue;
      }
      break;
    }
    if (mantissa >= PARSE_FLOAT_MANTISSA_LIMIT)
      break;
    mantissa = mantissa * 10 + d;
  }
  const uint32_t fraction_digits = dot != nullptr ? p - dot - 1 : 0;
  const bool any_digit = p - digits > (dot != nullptr ? 1 : 0);
  if (*p == '\0' && any_digit && fraction_digits <= PARSE_FLOAT_MAX_FRACTION_DIGITS) {
    // The mantissa is exact in a float, so the sign goes on before the one rounding step
    float value = static_cast<float>(mantissa);
    if (negative)
      value = -value;
    if (fraction_digits != 0) {
      uint32_t scale = 10;
      for (uint32_t i = 1; i < fraction_digits; i++)
        scale *= 10;
      value /= static_cast<float>(scale);
    }
    return value;
  }
  // Exponents, hex, inf, nan, leading whitespace and longer inputs take the libc path.
  char *end = nullptr;
  const float value = ::strtof(str, &end);
  if (end == str || *end != '\0' || value == HUGE_VALF)
    return {};
  return value;
}
 
size_t parse_hex(const char *str, size_t length, uint8_t *data, size_t count) {
  size_t chars = std::min(length, 2 * count);
  for (size_t i = 2 * count - chars; i < 2 * count; i++, str++) {
    uint8_t val = parse_hex_char(*str);
    if (val == INVALID_HEX_CHAR)
      return 0;
    data[i >> 1] = (i & 1) ? data[i >> 1] | val : val << 4;
  }
  return chars;
}
 
// Internal helper for hex formatting - base is 'a' for lowercase or 'A' for uppercase.
// When separator is set, it is written unconditionally after each byte and the last
// one is overwritten with '\0', eliminating the per-byte `i < length - 1` check.
static char *format_hex_internal(char *buffer, size_t buffer_size, const uint8_t *data, size_t length, char separator,
                                 char base) {
  if (length == 0 || buffer_size == 0) {
    if (buffer_size > 0)
      buffer[0] = '\0';
    return buffer;
  }
  uint8_t stride = separator ? 3 : 2;
  size_t max_bytes = separator ? (buffer_size / 3) : ((buffer_size - 1) / 2);
  if (max_bytes == 0) {
    buffer[0] = '\0';
    return buffer;
  }
  if (length > max_bytes) {
    length = max_bytes;
  }
  for (size_t i = 0; i < length; i++) {
    size_t pos = i * stride;
    buffer[pos] = format_hex_char(data[i] >> 4, base);
    buffer[pos + 1] = format_hex_char(data[i] & 0x0F, base);
    if (separator) {
      buffer[pos + 2] = separator;
    }
  }
  // With separator: overwrite last separator with '\0'
  // Without: write '\0' after last hex char
  buffer[length * stride - (separator ? 1 : 0)] = '\0';
  return buffer;
}
 
char *uint32_to_str_unchecked(char *buf, uint32_t val) {
  if (val == 0) {
    *buf++ = '0';
    return buf;
  }
  char *start = buf;
  while (val > 0) {
    *buf++ = '0' + (val % 10);
    val /= 10;
  }
  std::reverse(start, buf);
  return buf;
}
 
char *format_hex_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
  return format_hex_internal(buffer, buffer_size, data, length, 0, 'a');
}
 
const char *json_escape_into_buffer(std::span<char> buf, StringRef value, bool short_control_escapes) {
  if (buf.empty())
    return "";
  // Reserve one byte for the null terminator.
  const size_t limit = buf.size() - 1;
  size_t pos = 0;
  for (char ch : value) {
    auto c = static_cast<unsigned char>(ch);
    // Every short form is a backslash followed by a single character, so only that character is needed here. Keeping
    // it a char rather than a string avoids putting the sequences in read only data, which is RAM on the ESP8266.
    char escape = '\0';
    switch (c) {
      case '"':
        escape = '"';
        break;
      case '\\':
        escape = '\\';
        break;
      case '\n':
        escape = 'n';
        break;
      case '\r':
        escape = 'r';
        break;
      case '\t':
        escape = 't';
        break;
      case '\b':
        escape = 'b';
        break;
      case '\f':
        escape = 'f';
        break;
      default:
        break;
    }
    // " and \ are always written as two characters, but the control characters fall through to \u00XX when the
    // caller did not ask for the short forms.
    if (!short_control_escapes && c < 0x20)
      escape = '\0';
    if (escape != '\0') {
      if (pos + 2 > limit)
        break;
      buf[pos++] = '\\';
      buf[pos++] = escape;
    } else if (c < 0x20) {
      // Remaining control characters have no short form and must be written as \u00XX. The value is below 0x20, so
      // the two high hex digits are always zero.
      if (pos + JSON_ESCAPE_MAX_EXPANSION > limit)
        break;
      buf[pos++] = '\\';
      buf[pos++] = 'u';
      buf[pos++] = '0';
      buf[pos++] = '0';
      buf[pos++] = format_hex_char(static_cast<uint8_t>(c >> 4));
      buf[pos++] = format_hex_char(static_cast<uint8_t>(c & 0x0F));
    } else {
      if (pos + 1 > limit)
        break;
      buf[pos++] = static_cast<char>(c);
    }
  }
  buf[pos] = '\0';
  return buf.data();
}
 
char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length, char separator) {
  return format_hex_internal(buffer, buffer_size, data, length, separator, 'A');
}
 
char *format_hex_pretty_to(char *buffer, size_t buffer_size, const uint16_t *data, size_t length, char separator) {
  if (length == 0 || buffer_size == 0) {
    if (buffer_size > 0)
      buffer[0] = '\0';
    return buffer;
  }
  // With separator: each uint16_t needs 5 chars (4 hex + 1 sep), except last has no separator
  // Without separator: each uint16_t needs 4 chars, plus null terminator
  uint8_t stride = separator ? 5 : 4;
  size_t max_values = separator ? (buffer_size / stride) : ((buffer_size - 1) / stride);
  if (max_values == 0) {
    buffer[0] = '\0';
    return buffer;
  }
  if (length > max_values) {
    length = max_values;
  }
  for (size_t i = 0; i < length; i++) {
    size_t pos = i * stride;
    buffer[pos] = format_hex_pretty_char((data[i] & 0xF000) >> 12);
    buffer[pos + 1] = format_hex_pretty_char((data[i] & 0x0F00) >> 8);
    buffer[pos + 2] = format_hex_pretty_char((data[i] & 0x00F0) >> 4);
    buffer[pos + 3] = format_hex_pretty_char(data[i] & 0x000F);
    if (separator && i < length - 1) {
      buffer[pos + 4] = separator;
    }
  }
  buffer[length * stride - (separator ? 1 : 0)] = '\0';
  return buffer;
}
 
char *format_bin_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
  if (buffer_size == 0) {
    return buffer;
  }
  // Calculate max bytes we can format: each byte needs 8 chars
  size_t max_bytes = (buffer_size - 1) / 8;
  if (max_bytes == 0 || length == 0) {
    buffer[0] = '\0';
    return buffer;
  }
  size_t bytes_to_format = std::min(length, max_bytes);
 
  for (size_t byte_idx = 0; byte_idx < bytes_to_format; byte_idx++) {
    for (size_t bit_idx = 0; bit_idx < 8; bit_idx++) {
      buffer[byte_idx * 8 + bit_idx] = ((data[byte_idx] >> (7 - bit_idx)) & 1) + '0';
    }
  }
  buffer[bytes_to_format * 8] = '\0';
  return buffer;
}
 
ParseOnOffState parse_on_off(const char *str, const char *on, const char *off) {
  if (on == nullptr && ESPHOME_strcasecmp_P(str, ESPHOME_PSTR("on")) == 0)
    return PARSE_ON;
  if (on != nullptr && strcasecmp(str, on) == 0)
    return PARSE_ON;
  if (off == nullptr && ESPHOME_strcasecmp_P(str, ESPHOME_PSTR("off")) == 0)
    return PARSE_OFF;
  if (off != nullptr && strcasecmp(str, off) == 0)
    return PARSE_OFF;
  if (ESPHOME_strcasecmp_P(str, ESPHOME_PSTR("toggle")) == 0)
    return PARSE_TOGGLE;
 
  return PARSE_NONE;
}
 
int8_t ilog10(float value) {
  float abs_val = fabsf(value);
  int8_t exp = 0;
  if (abs_val >= 10.0f) {
    while (abs_val >= 10.0f) {
      abs_val /= 10.0f;
      exp++;
    }
  } else if (abs_val < 1.0f) {
    while (abs_val < 1.0f) {
      abs_val *= 10.0f;
      exp--;
    }
  }
  return exp;
}
 
static inline void normalize_accuracy_decimals(float &value, int8_t &accuracy_decimals) {
  if (accuracy_decimals < 0) {
    float divisor;
    if (accuracy_decimals == -1) {
      divisor = 10.0f;
    } else if (accuracy_decimals == -2) {
      divisor = 100.0f;
    } else {
      divisor = pow10_int(-accuracy_decimals);
    }
    value = roundf(value / divisor) * divisor;
    accuracy_decimals = 0;
  }
}
 
// Fast float-to-string for accuracy_decimals 0-4 (covers sensors and small PID coefficients).
// Avoids snprintf("%.*f") which pulls in heavy float formatting machinery.
// Caller must guarantee value is finite and |value| * mult fits in uint32_t.
static size_t value_accuracy_to_buf_fast(char *buf, float value, int8_t accuracy_decimals, uint32_t mult) {
  char *p = buf;
  if (std::signbit(value)) {
    *p++ = '-';
    value = -value;
  }
  // Cast to double for the multiply to match snprintf's rounding precision.
  // float*int loses bits at exact-half boundaries (e.g. 23.45f*10 = 234.5 in float,
  // but snprintf sees 234.500007... via double promotion and rounds differently).
  // llrint returns long long so the result fits even on 32-bit targets where
  // long is 32-bit; caller has already bounded |value * mult| to UINT32_MAX.
  uint32_t scaled = static_cast<uint32_t>(llrint(static_cast<double>(value) * mult));
  p = uint32_to_str_unchecked(p, scaled / mult);
  if (accuracy_decimals > 0) {
    *p++ = '.';
    p = frac_to_str_unchecked(p, scaled % mult, mult / 10);
  }
  *p = '\0';
  return static_cast<size_t>(p - buf);
}
 
size_t value_accuracy_to_buf(std::span<char, VALUE_ACCURACY_MAX_LEN> buf, float value, int8_t accuracy_decimals) {
  normalize_accuracy_decimals(value, accuracy_decimals);
 
  // Fast path for accuracy 0-4, finite values whose scaled magnitude fits in uint32_t.
  // For 4 decimals that's |value| < ~4.29e5; larger totals fall through to snprintf.
  if (accuracy_decimals <= 4 && std::isfinite(value)) {
    const uint32_t mult = small_pow10(accuracy_decimals);
    if (std::fabs(value) < static_cast<float>(UINT32_MAX) / mult) {
      return value_accuracy_to_buf_fast(buf.data(), value, accuracy_decimals, mult);
    }
  }
 
  // Fallback for NaN/Inf/high accuracy/out-of-range
  int len = snprintf(buf.data(), buf.size(), "%.*f", accuracy_decimals, static_cast<double>(value));
  if (len < 0)
    return 0;
  return static_cast<size_t>(len) >= buf.size() ? buf.size() - 1 : static_cast<size_t>(len);
}
 
size_t value_accuracy_with_uom_to_buf(std::span<char, VALUE_ACCURACY_MAX_LEN> buf, float value,
                                      int8_t accuracy_decimals, StringRef unit_of_measurement) {
  size_t len = value_accuracy_to_buf(buf, value, accuracy_decimals);
  if (len == 0 || unit_of_measurement.empty()) {
    return len;
  }
  char *end = buf_append_sep_str(buf.data() + len, buf.size() - len, ' ', unit_of_measurement.c_str(),
                                 unit_of_measurement.size());
  return static_cast<size_t>(end - buf.data());
}
 
int8_t step_to_accuracy_decimals(float step) {
  // Decimals needed to show the step at five significant digits, trailing zeros dropped.
  if (!std::isfinite(step) || step == 0.0f)
    return 0;
  float mantissa = std::fabs(step);
  int8_t decimals = 4;  // decimals needed for five significant digits when mantissa is in [1, 10)
  while (mantissa >= 10.0f) {
    mantissa /= 10.0f;
    decimals--;
  }
  while (mantissa < 1.0f) {
    mantissa *= 10.0f;
    decimals++;
  }
  if (decimals <= 0)
    return 0;
  float scaled = mantissa * 10000.0f;
  auto digits = static_cast<uint32_t>(scaled);
  if (scaled - static_cast<float>(digits) >= 0.5f)
    digits++;
  while (decimals > 0 && digits % 10 == 0) {
    digits /= 10;
    decimals--;
  }
  return decimals;
}
 
static constexpr uint8_t INVALID_BASE64_CHAR = 0xFF;
 
// 6-bit value of a base64 or base64url char, or INVALID_BASE64_CHAR.
// No lookup table: .rodata lives in DRAM on ESP8266.
static constexpr uint8_t base64_char_value(uint8_t c) {
  if (c >= 'A' && c <= 'Z')
    return c - 'A';
  if (c >= 'a' && c <= 'z')
    return c - 'a' + 26;
  if (c >= '0' && c <= '9')
    return c - '0' + 52;
  // base64url variants: '-' maps to '+' (index 62), '_' maps to '/' (index 63)
  if (c == '+' || c == '-')
    return 62;
  if (c == '/' || c == '_')
    return 63;
  return INVALID_BASE64_CHAR;
}
 
size_t base64_decode(const std::string &encoded_string, uint8_t *buf, size_t buf_len) {
  return base64_decode(reinterpret_cast<const uint8_t *>(encoded_string.data()), encoded_string.size(), buf, buf_len);
}
 
size_t base64_decode(const uint8_t *encoded_data, size_t encoded_len, uint8_t *buf, size_t buf_len) {
  size_t out = 0;
  uint32_t accum = 0;
  uint32_t bits = 0;
  // Stops at '=' or any non-alphabet char; leftover bits of a partial group are dropped.
  for (size_t in = 0; in < encoded_len; in++) {
    uint8_t value = base64_char_value(encoded_data[in]);
    if (value == INVALID_BASE64_CHAR)
      break;
    accum = (accum << 6) | value;
    bits += 6;
    if (bits >= 8) {
      bits -= 8;
      if (out == buf_len) {
        ESP_LOGW(TAG, "Base64 decode: buffer too small, truncating");
        return out;
      }
      buf[out++] = static_cast<uint8_t>(accum >> bits);
    }
  }
  return out;
}
 
bool base64_decode_int32_vector(const std::string &base64, std::vector<int32_t> &out) {
  // Decode in chunks to minimize stack usage
  constexpr size_t chunk_bytes = 48;  // 12 int32 values
  constexpr size_t chunk_chars = 64;  // 48 * 4/3 = 64 chars
  uint8_t chunk[chunk_bytes];
 
  out.clear();
 
  const uint8_t *input = reinterpret_cast<const uint8_t *>(base64.data());
  size_t remaining = base64.size();
  size_t pos = 0;
 
  while (remaining > 0) {
    size_t chars_to_decode = std::min(remaining, chunk_chars);
    size_t decoded_len = base64_decode(input + pos, chars_to_decode, chunk, chunk_bytes);
 
    if (decoded_len == 0)
      return false;
 
    // Parse little-endian int32 values
    for (size_t i = 0; i + 3 < decoded_len; i += 4) {
      int32_t timing = static_cast<int32_t>(encode_uint32(chunk[i + 3], chunk[i + 2], chunk[i + 1], chunk[i]));
      out.push_back(timing);
    }
 
    // Check for incomplete int32 in last chunk
    if (remaining <= chunk_chars && (decoded_len % 4) != 0)
      return false;
 
    pos += chars_to_decode;
    remaining -= chars_to_decode;
  }
 
  return !out.empty();
}
 
// Colors
 
void rgb_to_hsv(float red, float green, float blue, int &hue, float &saturation, float &value) {
  float max_color_value = std::max({red, green, blue});
  float min_color_value = std::min({red, green, blue});
  float delta = max_color_value - min_color_value;
 
  if (delta == 0) {
    hue = 0;
  } else if (max_color_value == red) {
    hue = int(fmodf((60.0f * ((green - blue) / delta)) + 360.0f, 360.0f));
  } else if (max_color_value == green) {
    hue = int(fmodf((60.0f * ((blue - red) / delta)) + 120.0f, 360.0f));
  } else if (max_color_value == blue) {
    hue = int(fmodf((60.0f * ((red - green) / delta)) + 240.0f, 360.0f));
  }
 
  if (max_color_value == 0) {
    saturation = 0;
  } else {
    saturation = delta / max_color_value;
  }
 
  value = max_color_value;
}
void hsv_to_rgb(int hue, float saturation, float value, float &red, float &green, float &blue) {
  float chroma = value * saturation;
  float hue_prime = fmodf(hue / 60.0f, 6.0f);
  float intermediate = chroma * (1.0f - fabsf(fmodf(hue_prime, 2.0f) - 1.0f));
  float delta = value - chroma;
 
  if (0 <= hue_prime && hue_prime < 1) {
    red = chroma;
    green = intermediate;
    blue = 0;
  } else if (1 <= hue_prime && hue_prime < 2) {
    red = intermediate;
    green = chroma;
    blue = 0;
  } else if (2 <= hue_prime && hue_prime < 3) {
    red = 0;
    green = chroma;
    blue = intermediate;
  } else if (3 <= hue_prime && hue_prime < 4) {
    red = 0;
    green = intermediate;
    blue = chroma;
  } else if (4 <= hue_prime && hue_prime < 5) {
    red = intermediate;
    green = 0;
    blue = chroma;
  } else if (5 <= hue_prime && hue_prime < 6) {
    red = chroma;
    green = 0;
    blue = intermediate;
  } else {
    red = 0;
    green = 0;
    blue = 0;
  }
 
  red += delta;
  green += delta;
  blue += delta;
}
 
uint8_t HighFrequencyLoopRequester::num_requests = 0;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
void HighFrequencyLoopRequester::start() {
  if (this->started_)
    return;
  num_requests++;
  this->started_ = true;
}
void HighFrequencyLoopRequester::stop() {
  if (!this->started_)
    return;
  num_requests--;
  this->started_ = false;
}
 
void get_mac_address_into_buffer(std::span<char, MAC_ADDRESS_BUFFER_SIZE> buf) {
  uint8_t mac[MAC_ADDRESS_SIZE];
  get_mac_address_raw(mac);
  format_mac_addr_lower_no_sep(mac, buf.data());
}
 
const char *get_mac_address_pretty_into_buffer(std::span<char, MAC_ADDRESS_PRETTY_BUFFER_SIZE> buf) {
  uint8_t mac[MAC_ADDRESS_SIZE];
  get_mac_address_raw(mac);
  format_mac_addr_upper(mac, buf.data());
  return buf.data();
}
 
#ifndef USE_ESP32
bool has_custom_mac_address() { return false; }
#endif
 
bool mac_address_is_valid(const uint8_t *mac) {
  bool is_all_zeros = true;
  bool is_all_ones = true;
 
  for (uint8_t i = 0; i < 6; i++) {
    if (mac[i] != 0) {
      is_all_zeros = false;
    }
    if (mac[i] != 0xFF) {
      is_all_ones = false;
    }
  }
  if (is_all_zeros || is_all_ones) {
    return false;
  }
  // Reject multicast MACs (bit 0 of first byte set) - device MACs must be unicast.
  // This catches garbage data from corrupted eFuse custom MAC areas, which often
  // has random values that would otherwise pass the all-zeros/all-ones check.
  if (mac[0] & 0x01) {
    return false;
  }
  return true;
}
 
void IRAM_ATTR HOT delay_microseconds_safe(uint32_t us) {
  // avoids CPU locks that could trigger WDT or affect WiFi/BT stability
  uint32_t start = micros();
 
  constexpr uint32_t lag = 5000;  // microseconds, specifies the maximum time for a CPU busy-loop.
                                  // it must be larger than the worst-case duration of a delay(1) call (hardware tasks)
                                  // 5ms is conservative, it could be reduced when exact BT/WiFi stack delays are known
  if (us > lag) {
    delay((us - lag) / 1000UL);  // note: in disabled-interrupt contexts delay() won't actually sleep
    while (micros() - start < us - lag)
      delay(1);  // in those cases, this loop allows to yield for BT/WiFi stack tasks
  }
  while (micros() - start < us)  // fine delay the remaining usecs
    ;
}
 
}  // namespace esphome