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[api] Return header length from write_plaintext_header instead of pointer

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Returning total_header_len lets callers compute msg_len directly
(header_len + payload_size) instead of reloading frame_header_padding_
from memory and doing pointer subtraction after encode_varint calls
clobber registers. Saves ~10 bytes in write_protobuf_packet.
This commit is contained in:
J. Nick Koston
2026-03-29 14:26:50 -10:00
parent a84d36cb37
commit a19a6f2a0e
1 changed files with 10 additions and 10 deletions
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esphome/components/api/api_frame_helper_plaintext.cpp
+10 -10
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@@ -235,9 +235,9 @@ APIError APIPlaintextFrameHelper::read_packet(ReadPacketBuffer *buffer) {
return APIError::OK;
}
// Write plaintext header into pre-allocated padding before payload.
// Returns pointer to start of frame (header + payload are contiguous).
ESPHOME_ALWAYS_INLINE static inline uint8_t *write_plaintext_header(uint8_t *buf_start, const MessageInfo &msg,
uint8_t frame_header_padding) {
// Returns the total header length (indicator + varints).
ESPHOME_ALWAYS_INLINE static inline uint8_t write_plaintext_header(uint8_t *buf_start, const MessageInfo &msg,
uint8_t frame_header_padding) {
// Calculate varint sizes for header layout using inline ternary to avoid varint_slow call overhead
uint8_t size_varint_len = msg.payload_size < ProtoSize::VARINT_THRESHOLD_1_BYTE
? 1
@@ -279,7 +279,7 @@ ESPHOME_ALWAYS_INLINE static inline uint8_t *write_plaintext_header(uint8_t *buf
encode_varint_to_buffer(msg.payload_size, buf_start + header_offset + 1);
encode_varint_to_buffer(msg.message_type, buf_start + header_offset + 1 + size_varint_len);
return buf_start + header_offset;
return total_header_len;
}
APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
@@ -289,9 +289,9 @@ APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWrite
MessageInfo msg{type, 0, static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_)};
uint8_t *buffer_data = buffer.get_buffer()->data();
uint8_t *msg_start = write_plaintext_header(buffer_data, msg, frame_header_padding_);
uint8_t msg_header_len = static_cast<uint8_t>(buffer_data + frame_header_padding_ - msg_start);
uint16_t msg_len = static_cast<uint16_t>(msg_header_len + msg.payload_size);
uint8_t header_len = write_plaintext_header(buffer_data, msg, frame_header_padding_);
uint8_t *msg_start = buffer_data + frame_header_padding_ - header_len;
uint16_t msg_len = static_cast<uint16_t>(header_len + msg.payload_size);
LOG_PACKET_SENDING(msg_start, msg_len);
return this->write_raw_fast_buf_(msg_start, msg_len);
}
@@ -309,9 +309,9 @@ APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffe
const uint8_t padding = frame_header_padding_;
for (const auto &msg : messages) {
uint8_t *msg_start = write_plaintext_header(buffer_data + msg.offset, msg, padding);
uint8_t msg_header_len = static_cast<uint8_t>((buffer_data + msg.offset + padding) - msg_start);
size_t msg_len = static_cast<size_t>(msg_header_len + msg.payload_size);
uint8_t header_len = write_plaintext_header(buffer_data + msg.offset, msg, padding);
uint8_t *msg_start = buffer_data + msg.offset + padding - header_len;
size_t msg_len = static_cast<size_t>(header_len + msg.payload_size);
iovs.push_back({msg_start, msg_len});
total_write_len += msg_len;
}