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Extract varint_wide helper to deduplicate cascade

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The constexpr path and the noinline slow path shared the same
if/else cascade for values >= 128. Extract into a private
constexpr ESPHOME_ALWAYS_INLINE helper used by both.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
J. Nick Koston
2026-03-07 15:41:01 -10:00
parent 44b50055af
commit a5780eec54
2 changed files with 16 additions and 22 deletions
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esphome/components/api/proto.cpp
+1 -12
View File
@@ -8,18 +8,7 @@ namespace esphome::api {
static const char *const TAG = "api.proto";
uint32_t ProtoSize::varint_slow(uint32_t value) {
// value is guaranteed >= 128 here (fast path handled inline)
if (value < 16384) {
return 2; // 14 bits
} else if (value < 2097152) {
return 3; // 21 bits
} else if (value < 268435456) {
return 4; // 28 bits
} else {
return 5; // 32 bits (maximum for uint32_t)
}
}
uint32_t ProtoSize::varint_slow(uint32_t value) { return varint_wide(value); }
#ifdef USE_API_VARINT64
optional<ProtoVarInt> ProtoVarInt::parse_wide(const uint8_t *buffer, uint32_t len, uint32_t *consumed,
esphome/components/api/proto.h
+15 -10
View File
@@ -514,21 +514,26 @@ class ProtoSize {
static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE varint(uint32_t value) {
if (value < 128)
return 1; // Fast path: 7 bits, most common case
if (__builtin_is_constant_evaluated()) {
// Compile-time: full cascade for constexpr callers
if (value < 16384)
return 2;
if (value < 2097152)
return 3;
if (value < 268435456)
return 4;
return 5;
}
if (__builtin_is_constant_evaluated())
return varint_wide(value);
return varint_slow(value);
}
// Slow path for varint >= 128, outlined to keep fast path small
static uint32_t varint_slow(uint32_t value) __attribute__((noinline));
private:
// Shared cascade for values >= 128 (used by both constexpr and noinline paths)
static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE varint_wide(uint32_t value) {
if (value < 16384)
return 2;
if (value < 2097152)
return 3;
if (value < 268435456)
return 4;
return 5;
}
public:
/**
* @brief Calculates the size in bytes needed to encode a uint64_t value as a varint
*