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Address review: clamp to MAX_BITS, add ctzll branch for >32-bit masks

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Clamp the __builtin_ctz result to MAX_BITS to match the original loop
semantics if out-of-range bits are ever present. Add ctzll branch for
hypothetical >32-bit bitmask types.
This commit is contained in:
J. Nick Koston
2026-04-02 13:48:36 -10:00
parent bce8e6ecb6
commit af41cc2d66
1 changed files with 11 additions and 6 deletions
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esphome/core/finite_set_mask.h
+11 -6
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@@ -157,14 +157,19 @@ template<typename ValueType, typename BitPolicy = DefaultBitPolicy<ValueType, 16
/// Find the lowest set bit in a bitmask
/// Returns the bit position, or MAX_BITS if no bits are set
static constexpr int find_lowest_set_bit(bitmask_t mask) {
if (mask == 0)
if (mask == 0) {
return BitPolicy::MAX_BITS;
#if defined(__GNUC__) || defined(__clang__)
if constexpr (sizeof(bitmask_t) <= sizeof(unsigned int)) {
return __builtin_ctz(static_cast<unsigned int>(mask));
} else {
return __builtin_ctzl(static_cast<uint32_t>(mask));
}
#if defined(__GNUC__) || defined(__clang__)
int bit;
if constexpr (sizeof(bitmask_t) <= sizeof(unsigned int)) {
bit = __builtin_ctz(static_cast<unsigned int>(mask));
} else if constexpr (sizeof(bitmask_t) <= sizeof(uint32_t)) {
bit = __builtin_ctzl(static_cast<uint32_t>(mask));
} else {
bit = __builtin_ctzll(static_cast<unsigned long long>(mask));
}
return bit < BitPolicy::MAX_BITS ? bit : BitPolicy::MAX_BITS;
#else
int bit = 0;
while (bit < BitPolicy::MAX_BITS && !(mask & (static_cast<bitmask_t>(1) << bit))) {