[api] Inline ProtoVarInt::parse fast path and return consumed in struct (#14638)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -128,37 +128,37 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
 
     // Skip indicator byte at position 0
     uint8_t varint_pos = 1;
-    uint32_t consumed = 0;
 
-    auto msg_size_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos, &consumed);
+    // rx_header_buf_pos_ >= 3 and varint_pos == 1, so len >= 2
+    auto msg_size_varint = ProtoVarInt::parse_non_empty(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos);
     if (!msg_size_varint.has_value()) {
       // not enough data there yet
       continue;
     }
 
-    if (msg_size_varint->as_uint32() > MAX_MESSAGE_SIZE) {
+    if (msg_size_varint.value > MAX_MESSAGE_SIZE) {
       state_ = State::FAILED;
-      HELPER_LOG("Bad packet: message size %" PRIu32 " exceeds maximum %u", msg_size_varint->as_uint32(),
-                 MAX_MESSAGE_SIZE);
+      HELPER_LOG("Bad packet: message size %" PRIu32 " exceeds maximum %u",
+                 static_cast<uint32_t>(msg_size_varint.value), MAX_MESSAGE_SIZE);
       return APIError::BAD_DATA_PACKET;
     }
-    rx_header_parsed_len_ = msg_size_varint->as_uint16();
+    rx_header_parsed_len_ = static_cast<uint16_t>(msg_size_varint.value);
 
     // Move to next varint position
-    varint_pos += consumed;
+    varint_pos += msg_size_varint.consumed;
 
-    auto msg_type_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos, &consumed);
+    auto msg_type_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos);
     if (!msg_type_varint.has_value()) {
       // not enough data there yet
       continue;
     }
-    if (msg_type_varint->as_uint32() > std::numeric_limits<uint16_t>::max()) {
+    if (msg_type_varint.value > std::numeric_limits<uint16_t>::max()) {
       state_ = State::FAILED;
-      HELPER_LOG("Bad packet: message type %" PRIu32 " exceeds maximum %u", msg_type_varint->as_uint32(),
-                 std::numeric_limits<uint16_t>::max());
+      HELPER_LOG("Bad packet: message type %" PRIu32 " exceeds maximum %u",
+                 static_cast<uint32_t>(msg_type_varint.value), std::numeric_limits<uint16_t>::max());
       return APIError::BAD_DATA_PACKET;
     }
-    rx_header_parsed_type_ = msg_type_varint->as_uint16();
+    rx_header_parsed_type_ = static_cast<uint16_t>(msg_type_varint.value);
     rx_header_parsed_ = true;
   }
   // header reading done

esphome/components/api/api_pb2.h

@@ -399,7 +399,7 @@ class HelloRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class HelloResponse final : public ProtoMessage {
  public:
@@ -688,7 +688,7 @@ class CoverCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_FAN
@@ -756,7 +756,7 @@ class FanCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_LIGHT
@@ -846,7 +846,7 @@ class LightCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_SENSOR
@@ -936,7 +936,7 @@ class SwitchCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_TEXT_SENSOR
@@ -988,7 +988,7 @@ class SubscribeLogsRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SubscribeLogsResponse final : public ProtoMessage {
  public:
@@ -1110,7 +1110,7 @@ class HomeassistantActionResponse final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
@@ -1176,7 +1176,7 @@ class DSTRule final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class ParsedTimezone final : public ProtoDecodableMessage {
  public:
@@ -1190,7 +1190,7 @@ class ParsedTimezone final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class GetTimeResponse final : public ProtoDecodableMessage {
  public:
@@ -1261,7 +1261,7 @@ class ExecuteServiceArgument final : public ProtoDecodableMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class ExecuteServiceRequest final : public ProtoDecodableMessage {
  public:
@@ -1286,7 +1286,7 @@ class ExecuteServiceRequest final : public ProtoDecodableMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES
@@ -1365,7 +1365,7 @@ class CameraImageRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_CLIMATE
@@ -1464,7 +1464,7 @@ class ClimateCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_WATER_HEATER
@@ -1528,7 +1528,7 @@ class WaterHeaterCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_NUMBER
@@ -1584,7 +1584,7 @@ class NumberCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_SELECT
@@ -1636,7 +1636,7 @@ class SelectCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_SIREN
@@ -1696,7 +1696,7 @@ class SirenCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_LOCK
@@ -1752,7 +1752,7 @@ class LockCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_BUTTON
@@ -1785,7 +1785,7 @@ class ButtonCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_MEDIA_PLAYER
@@ -1862,7 +1862,7 @@ class MediaPlayerCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_BLUETOOTH_PROXY
@@ -1879,7 +1879,7 @@ class SubscribeBluetoothLEAdvertisementsRequest final : public ProtoDecodableMes
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothLERawAdvertisement final : public ProtoMessage {
  public:
@@ -1929,7 +1929,7 @@ class BluetoothDeviceRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothDeviceConnectionResponse final : public ProtoMessage {
  public:
@@ -1963,7 +1963,7 @@ class BluetoothGATTGetServicesRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTDescriptor final : public ProtoMessage {
  public:
@@ -2054,7 +2054,7 @@ class BluetoothGATTReadRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTReadResponse final : public ProtoMessage {
  public:
@@ -2097,7 +2097,7 @@ class BluetoothGATTWriteRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTReadDescriptorRequest final : public ProtoDecodableMessage {
  public:
@@ -2113,7 +2113,7 @@ class BluetoothGATTReadDescriptorRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTWriteDescriptorRequest final : public ProtoDecodableMessage {
  public:
@@ -2132,7 +2132,7 @@ class BluetoothGATTWriteDescriptorRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTNotifyRequest final : public ProtoDecodableMessage {
  public:
@@ -2149,7 +2149,7 @@ class BluetoothGATTNotifyRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothGATTNotifyDataResponse final : public ProtoMessage {
  public:
@@ -2329,7 +2329,7 @@ class BluetoothScannerSetModeRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_VOICE_ASSISTANT
@@ -2347,7 +2347,7 @@ class SubscribeVoiceAssistantRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantAudioSettings final : public ProtoMessage {
  public:
@@ -2396,7 +2396,7 @@ class VoiceAssistantResponse final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantEventData final : public ProtoDecodableMessage {
  public:
@@ -2424,7 +2424,7 @@ class VoiceAssistantEventResponse final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantAudio final : public ProtoDecodableMessage {
  public:
@@ -2444,7 +2444,7 @@ class VoiceAssistantAudio final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantTimerEventResponse final : public ProtoDecodableMessage {
  public:
@@ -2465,7 +2465,7 @@ class VoiceAssistantTimerEventResponse final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantAnnounceRequest final : public ProtoDecodableMessage {
  public:
@@ -2484,7 +2484,7 @@ class VoiceAssistantAnnounceRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantAnnounceFinished final : public ProtoMessage {
  public:
@@ -2530,7 +2530,7 @@ class VoiceAssistantExternalWakeWord final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class VoiceAssistantConfigurationRequest final : public ProtoDecodableMessage {
  public:
@@ -2632,7 +2632,7 @@ class AlarmControlPanelCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_TEXT
@@ -2687,7 +2687,7 @@ class TextCommandRequest final : public CommandProtoMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_DATETIME_DATE
@@ -2741,7 +2741,7 @@ class DateCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_DATETIME_TIME
@@ -2795,7 +2795,7 @@ class TimeCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_EVENT
@@ -2886,7 +2886,7 @@ class ValveCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_DATETIME_DATETIME
@@ -2936,7 +2936,7 @@ class DateTimeCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_UPDATE
@@ -2994,7 +2994,7 @@ class UpdateCommandRequest final : public CommandProtoMessage {
 
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_ZWAVE_PROXY
@@ -3034,7 +3034,7 @@ class ZWaveProxyRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 #endif
 #ifdef USE_INFRARED
@@ -3079,7 +3079,7 @@ class InfraredRFTransmitRawTimingsRequest final : public ProtoDecodableMessage {
  protected:
   bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class InfraredRFReceiveEvent final : public ProtoMessage {
  public:
@@ -3121,7 +3121,7 @@ class SerialProxyConfigureRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SerialProxyDataReceived final : public ProtoMessage {
  public:
@@ -3161,7 +3161,7 @@ class SerialProxyWriteRequest final : public ProtoDecodableMessage {
 
  protected:
   bool decode_length(uint32_t field_id, ProtoLengthDelimited value) override;
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SerialProxySetModemPinsRequest final : public ProtoDecodableMessage {
  public:
@@ -3177,7 +3177,7 @@ class SerialProxySetModemPinsRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SerialProxyGetModemPinsRequest final : public ProtoDecodableMessage {
  public:
@@ -3192,7 +3192,7 @@ class SerialProxyGetModemPinsRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SerialProxyGetModemPinsResponse final : public ProtoMessage {
  public:
@@ -3225,7 +3225,7 @@ class SerialProxyRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class SerialProxyRequestResponse final : public ProtoMessage {
  public:
@@ -3265,7 +3265,7 @@ class BluetoothSetConnectionParamsRequest final : public ProtoDecodableMessage {
 #endif
 
  protected:
-  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
 class BluetoothSetConnectionParamsResponse final : public ProtoMessage {
  public:

esphome/components/api/proto.cpp

@@ -20,20 +20,40 @@ void ProtoWriteBuffer::encode_varint_raw_slow_(uint32_t value) {
   *this->pos_++ = static_cast<uint8_t>(value);
 }
 
+ProtoVarIntResult ProtoVarInt::parse_slow(const uint8_t *buffer, uint32_t len) {
+  // Multi-byte varint: first byte already checked to have high bit set
+  uint32_t result32 = buffer[0] & 0x7F;
 #ifdef USE_API_VARINT64
-optional<ProtoVarInt> ProtoVarInt::parse_wide(const uint8_t *buffer, uint32_t len, uint32_t *consumed,
-                                              uint32_t result32) {
+  uint32_t limit = std::min(len, uint32_t(4));
+#else
+  uint32_t limit = std::min(len, uint32_t(5));
+#endif
+  for (uint32_t i = 1; i < limit; i++) {
+    uint8_t val = buffer[i];
+    result32 |= uint32_t(val & 0x7F) << (i * 7);
+    if ((val & 0x80) == 0) {
+      return {result32, i + 1};
+    }
+  }
+#ifdef USE_API_VARINT64
+  return parse_wide(buffer, len, result32);
+#else
+  return {0, PROTO_VARINT_PARSE_FAILED};
+#endif
+}
+
+#ifdef USE_API_VARINT64
+ProtoVarIntResult ProtoVarInt::parse_wide(const uint8_t *buffer, uint32_t len, uint32_t result32) {
   uint64_t result64 = result32;
   uint32_t limit = std::min(len, uint32_t(10));
   for (uint32_t i = 4; i < limit; i++) {
     uint8_t val = buffer[i];
     result64 |= uint64_t(val & 0x7F) << (i * 7);
     if ((val & 0x80) == 0) {
-      *consumed = i + 1;
-      return ProtoVarInt(result64);
+      return {result64, i + 1};
     }
   }
-  return {};
+  return {0, PROTO_VARINT_PARSE_FAILED};
 }
 #endif
 
@@ -43,18 +63,16 @@ uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size
   const uint8_t *end = buffer + length;
 
   while (ptr < end) {
-    uint32_t consumed;
-
-    // Parse field header (tag)
-    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+    // Parse field header (tag) - ptr < end guarantees len >= 1
+    auto res = ProtoVarInt::parse_non_empty(ptr, end - ptr);
     if (!res.has_value()) {
       break;  // Invalid data, stop counting
     }
 
-    uint32_t tag = res->as_uint32();
+    uint32_t tag = static_cast<uint32_t>(res.value);
     uint32_t field_type = tag & WIRE_TYPE_MASK;
     uint32_t field_id = tag >> 3;
-    ptr += consumed;
+    ptr += res.consumed;
 
     // Count if this is the target field
     if (field_id == target_field_id) {
@@ -64,20 +82,20 @@ uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size
     // Skip field data based on wire type
     switch (field_type) {
       case WIRE_TYPE_VARINT: {  // VarInt - parse and skip
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           return count;  // Invalid data, return what we have
         }
-        ptr += consumed;
+        ptr += res.consumed;
         break;
       }
       case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited - parse length and skip data
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           return count;
         }
-        uint32_t field_length = res->as_uint32();
-        ptr += consumed;
+        uint32_t field_length = static_cast<uint32_t>(res.value);
+        ptr += res.consumed;
         if (field_length > static_cast<size_t>(end - ptr)) {
           return count;  // Out of bounds
         }
@@ -190,41 +208,40 @@ void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
   const uint8_t *end = buffer + length;
 
   while (ptr < end) {
-    uint32_t consumed;
-
-    // Parse field header
-    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+    // Parse field header - ptr < end guarantees len >= 1
+    auto res = ProtoVarInt::parse_non_empty(ptr, end - ptr);
     if (!res.has_value()) {
       ESP_LOGV(TAG, "Invalid field start at offset %ld", (long) (ptr - buffer));
       return;
     }
 
-    uint32_t tag = res->as_uint32();
+    uint32_t tag = static_cast<uint32_t>(res.value);
     uint32_t field_type = tag & WIRE_TYPE_MASK;
     uint32_t field_id = tag >> 3;
-    ptr += consumed;
+    ptr += res.consumed;
 
     switch (field_type) {
       case WIRE_TYPE_VARINT: {  // VarInt
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           ESP_LOGV(TAG, "Invalid VarInt at offset %ld", (long) (ptr - buffer));
           return;
         }
-        if (!this->decode_varint(field_id, *res)) {
-          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu32 "!", field_id, res->as_uint32());
+        if (!this->decode_varint(field_id, res.value)) {
+          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu64 "!", field_id,
+                   static_cast<uint64_t>(res.value));
         }
-        ptr += consumed;
+        ptr += res.consumed;
         break;
       }
       case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           ESP_LOGV(TAG, "Invalid Length Delimited at offset %ld", (long) (ptr - buffer));
           return;
         }
-        uint32_t field_length = res->as_uint32();
-        ptr += consumed;
+        uint32_t field_length = static_cast<uint32_t>(res.value);
+        ptr += res.consumed;
         if (field_length > static_cast<size_t>(end - ptr)) {
           ESP_LOGV(TAG, "Out-of-bounds Length Delimited at offset %ld", (long) (ptr - buffer));
           return;

esphome/components/api/proto.h

@@ -98,90 +98,56 @@ inline void encode_varint_to_buffer(uint32_t val, uint8_t *buffer) {
  * within the same function scope where temporaries are created.
  */
 
-/// Representation of a VarInt - in ProtoBuf should be 64bit but we only use 32bit
+/// Type used for decoded varint values - uint64_t when BLE needs 64-bit addresses, uint32_t otherwise
+#ifdef USE_API_VARINT64
+using proto_varint_value_t = uint64_t;
+#else
+using proto_varint_value_t = uint32_t;
+#endif
+
+/// Sentinel value for consumed field indicating parse failure
+inline constexpr uint32_t PROTO_VARINT_PARSE_FAILED = 0;
+
+/// Result of parsing a varint: value + number of bytes consumed.
+/// consumed == PROTO_VARINT_PARSE_FAILED indicates parse failure (not enough data or invalid).
+struct ProtoVarIntResult {
+  proto_varint_value_t value;
+  uint32_t consumed;  // PROTO_VARINT_PARSE_FAILED = parse failed
+
+  constexpr bool has_value() const { return this->consumed != PROTO_VARINT_PARSE_FAILED; }
+};
+
+/// Static varint parsing methods for the protobuf wire format.
 class ProtoVarInt {
  public:
-  ProtoVarInt() : value_(0) {}
-  explicit ProtoVarInt(uint64_t value) : value_(value) {}
-
-  /// Parse a varint from buffer. consumed must be a valid pointer (not null).
-  static optional<ProtoVarInt> parse(const uint8_t *buffer, uint32_t len, uint32_t *consumed) {
+  /// Parse a varint from buffer. Caller must ensure len >= 1.
+  /// Returns result with consumed=0 on failure (truncated multi-byte varint).
+  static inline ProtoVarIntResult ESPHOME_ALWAYS_INLINE parse_non_empty(const uint8_t *buffer, uint32_t len) {
 #ifdef ESPHOME_DEBUG_API
-    assert(consumed != nullptr);
+    assert(len > 0);
 #endif
-    if (len == 0)
-      return {};
     // Fast path: single-byte varints (0-127) are the most common case
-    // (booleans, small enums, field tags). Avoid loop overhead entirely.
-    if ((buffer[0] & 0x80) == 0) {
-      *consumed = 1;
-      return ProtoVarInt(buffer[0]);
-    }
-    // 32-bit phase: process remaining bytes with native 32-bit shifts.
-    // Without USE_API_VARINT64: cover bytes 1-4 (shifts 7, 14, 21, 28) — the uint32_t
-    // shift at byte 4 (shift by 28) may lose bits 32-34, but those are always zero for valid uint32 values.
-    // With USE_API_VARINT64: cover bytes 1-3 (shifts 7, 14, 21) so parse_wide handles
-    // byte 4+ with full 64-bit arithmetic (avoids truncating values > UINT32_MAX).
-    uint32_t result32 = buffer[0] & 0x7F;
-#ifdef USE_API_VARINT64
-    uint32_t limit = std::min(len, uint32_t(4));
-#else
-    uint32_t limit = std::min(len, uint32_t(5));
-#endif
-    for (uint32_t i = 1; i < limit; i++) {
-      uint8_t val = buffer[i];
-      result32 |= uint32_t(val & 0x7F) << (i * 7);
-      if ((val & 0x80) == 0) {
-        *consumed = i + 1;
-        return ProtoVarInt(result32);
-      }
-    }
-    // 64-bit phase for remaining bytes (BLE addresses etc.)
-#ifdef USE_API_VARINT64
-    return parse_wide(buffer, len, consumed, result32);
-#else
-    return {};
-#endif
+    // (booleans, small enums, field tags, small message sizes/types).
+    if ((buffer[0] & 0x80) == 0) [[likely]]
+      return {buffer[0], 1};
+    return parse_slow(buffer, len);
+  }
+
+  /// Parse a varint from buffer (safe for empty buffers).
+  /// Returns result with consumed=0 on failure (empty buffer or truncated varint).
+  static inline ProtoVarIntResult ESPHOME_ALWAYS_INLINE parse(const uint8_t *buffer, uint32_t len) {
+    if (len == 0)
+      return {0, PROTO_VARINT_PARSE_FAILED};
+    return parse_non_empty(buffer, len);
   }
 
-#ifdef USE_API_VARINT64
  protected:
+  // Slow path for multi-byte varints (>= 128), outlined to keep fast path small
+  static ProtoVarIntResult parse_slow(const uint8_t *buffer, uint32_t len) __attribute__((noinline));
+
+#ifdef USE_API_VARINT64
   /// Continue parsing varint bytes 4-9 with 64-bit arithmetic.
-  /// Separated to keep 64-bit shift code (__ashldi3 on 32-bit platforms) out of the common path.
-  static optional<ProtoVarInt> parse_wide(const uint8_t *buffer, uint32_t len, uint32_t *consumed, uint32_t result32)
-      __attribute__((noinline));
-
- public:
-#endif
-
-  constexpr uint16_t as_uint16() const { return this->value_; }
-  constexpr uint32_t as_uint32() const { return this->value_; }
-  constexpr bool as_bool() const { return this->value_; }
-  constexpr int32_t as_int32() const {
-    // Not ZigZag encoded
-    return static_cast<int32_t>(this->value_);
-  }
-  constexpr int32_t as_sint32() const {
-    // with ZigZag encoding
-    return decode_zigzag32(static_cast<uint32_t>(this->value_));
-  }
-#ifdef USE_API_VARINT64
-  constexpr uint64_t as_uint64() const { return this->value_; }
-  constexpr int64_t as_int64() const {
-    // Not ZigZag encoded
-    return static_cast<int64_t>(this->value_);
-  }
-  constexpr int64_t as_sint64() const {
-    // with ZigZag encoding
-    return decode_zigzag64(this->value_);
-  }
-#endif
-
- protected:
-#ifdef USE_API_VARINT64
-  uint64_t value_;
-#else
-  uint32_t value_;
+  static ProtoVarIntResult parse_wide(const uint8_t *buffer, uint32_t len, uint32_t result32) __attribute__((noinline));
 #endif
 };
 
@@ -499,7 +465,7 @@ class ProtoDecodableMessage : public ProtoMessage {
 
  protected:
   ~ProtoDecodableMessage() = default;
-  virtual bool decode_varint(uint32_t field_id, ProtoVarInt value) { return false; }
+  virtual bool decode_varint(uint32_t field_id, proto_varint_value_t value) { return false; }
   virtual bool decode_length(uint32_t field_id, ProtoLengthDelimited value) { return false; }
   virtual bool decode_32bit(uint32_t field_id, Proto32Bit value) { return false; }
   // NOTE: decode_64bit removed - wire type 1 not supported

script/api_protobuf/api_protobuf.py

@@ -461,7 +461,7 @@ class FloatType(TypeInfo):
 class Int64Type(TypeInfo):
     cpp_type = "int64_t"
     default_value = "0"
-    decode_varint = "value.as_int64()"
+    decode_varint = "static_cast<int64_t>(value)"
     encode_func = "encode_int64"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -481,7 +481,7 @@ class Int64Type(TypeInfo):
 class UInt64Type(TypeInfo):
     cpp_type = "uint64_t"
     default_value = "0"
-    decode_varint = "value.as_uint64()"
+    decode_varint = "value"
     encode_func = "encode_uint64"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -501,7 +501,7 @@ class UInt64Type(TypeInfo):
 class Int32Type(TypeInfo):
     cpp_type = "int32_t"
     default_value = "0"
-    decode_varint = "value.as_int32()"
+    decode_varint = "static_cast<int32_t>(value)"
     encode_func = "encode_int32"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -573,7 +573,7 @@ class Fixed32Type(TypeInfo):
 class BoolType(TypeInfo):
     cpp_type = "bool"
     default_value = "false"
-    decode_varint = "value.as_bool()"
+    decode_varint = "value != 0"
     encode_func = "encode_bool"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -1151,7 +1151,7 @@ class FixedArrayBytesType(TypeInfo):
 class UInt32Type(TypeInfo):
     cpp_type = "uint32_t"
     default_value = "0"
-    decode_varint = "value.as_uint32()"
+    decode_varint = "value"
     encode_func = "encode_uint32"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -1175,7 +1175,7 @@ class EnumType(TypeInfo):
 
     @property
     def decode_varint(self) -> str:
-        return f"static_cast<{self.cpp_type}>(value.as_uint32())"
+        return f"static_cast<{self.cpp_type}>(value)"
 
     default_value = ""
     wire_type = WireType.VARINT  # Uses wire type 0
@@ -1262,7 +1262,7 @@ class SFixed64Type(TypeInfo):
 class SInt32Type(TypeInfo):
     cpp_type = "int32_t"
     default_value = "0"
-    decode_varint = "value.as_sint32()"
+    decode_varint = "decode_zigzag32(static_cast<uint32_t>(value))"
     encode_func = "encode_sint32"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -1282,7 +1282,7 @@ class SInt32Type(TypeInfo):
 class SInt64Type(TypeInfo):
     cpp_type = "int64_t"
     default_value = "0"
-    decode_varint = "value.as_sint64()"
+    decode_varint = "decode_zigzag64(value)"
     encode_func = "encode_sint64"
     wire_type = WireType.VARINT  # Uses wire type 0
 
@@ -2205,7 +2205,7 @@ def build_message_type(
 
     cpp = ""
     if decode_varint:
-        o = f"bool {desc.name}::decode_varint(uint32_t field_id, ProtoVarInt value) {{\n"
+        o = f"bool {desc.name}::decode_varint(uint32_t field_id, proto_varint_value_t value) {{\n"
         o += "  switch (field_id) {\n"
         o += indent("\n".join(decode_varint), "    ") + "\n"
         o += "    default: return false;\n"
@@ -2213,7 +2213,7 @@ def build_message_type(
         o += "  return true;\n"
         o += "}\n"
         cpp += o
-        prot = "bool decode_varint(uint32_t field_id, ProtoVarInt value) override;"
+        prot = "bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;"
         protected_content.insert(0, prot)
     if decode_length:
         o = f"bool {desc.name}::decode_length(uint32_t field_id, ProtoLengthDelimited value) {{\n"