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Code Issues Releases Wiki Activity

fix

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This commit is contained in:
J. Nick Koston
2025-10-28 15:31:02 -05:00
parent fc2a447da7
commit fa8da1473f
1 changed files with 30 additions and 15 deletions
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45
esphome/components/api/proto.h
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@@ -213,9 +213,6 @@ class Proto32Bit {
// NOTE: Proto64Bit class removed - wire type 1 (64-bit fixed) not supported
// Forward declaration for ProtoSize (defined later in file)
class ProtoSize;
class ProtoWriteBuffer {
public:
ProtoWriteBuffer(std::vector<uint8_t> *buffer) : buffer_(buffer) {}
@@ -226,7 +223,7 @@ class ProtoWriteBuffer {
auto buffer = this->buffer_;
size_t start = buffer->size();
// Fast paths for common cases (1-4 bytes) - inline encoding avoids loop overhead
// Fast paths for common cases (1-3 bytes)
if (value < (1ULL << 7)) {
// 1 byte - very common for field IDs and small lengths
buffer->resize(start + 1);
@@ -236,7 +233,7 @@ class ProtoWriteBuffer {
uint8_t *p;
if (value < (1ULL << 14)) {
// 2 bytes
// 2 bytes - common for medium field IDs and lengths
buffer->resize(start + 2);
p = buffer->data() + start;
p[0] = (value & 0x7F) | 0x80;
@@ -244,7 +241,7 @@ class ProtoWriteBuffer {
return;
}
if (value < (1ULL << 21)) {
// 3 bytes
// 3 bytes - rare
buffer->resize(start + 3);
p = buffer->data() + start;
p[0] = (value & 0x7F) | 0x80;
@@ -253,8 +250,31 @@ class ProtoWriteBuffer {
return;
}
// Rare case: 4-10 byte values - delegate to ProtoSize to calculate size
uint32_t size = ProtoSize::varint(value);
// Rare case: 4-10 byte values - calculate size from bit position
// Value is guaranteed >= (1ULL << 21), so CLZ is safe (non-zero)
uint32_t size;
#if defined(__GNUC__) || defined(__clang__)
// Use compiler intrinsic for efficient bit position lookup
size = (64 - __builtin_clzll(value) + 6) / 7;
#else
// Fallback for compilers without __builtin_clzll
if (value < (1ULL << 28)) {
size = 4;
} else if (value < (1ULL << 35)) {
size = 5;
} else if (value < (1ULL << 42)) {
size = 6;
} else if (value < (1ULL << 49)) {
size = 7;
} else if (value < (1ULL << 56)) {
size = 8;
} else if (value < (1ULL << 63)) {
size = 9;
} else {
size = 10;
}
#endif
buffer->resize(start + size);
p = buffer->data() + start;
size_t bytes = 0;
@@ -479,12 +499,8 @@ class ProtoSize {
return varint(static_cast<uint32_t>(value));
}
// For larger values, calculate size from number of significant bits: ceil(bits / 7)
#if defined(__GNUC__) || defined(__clang__)
// Use compiler intrinsic for efficient bit position lookup
return (64 - __builtin_clzll(value) + 6) / 7;
#else
// Fallback for compilers without __builtin_clzll
// For larger values, use simple ladder (constexpr-friendly)
// Note: encode_varint_raw uses CLZ for runtime performance, but this is rarely called
if (value < (1ULL << 35)) {
return 5; // 35 bits
} else if (value < (1ULL << 42)) {
@@ -498,7 +514,6 @@ class ProtoSize {
} else {
return 10; // 64 bits (maximum for uint64_t)
}
#endif
}
/**