From 3c65cabe1dc7a1d94cb889617427f2239e6fb734 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rodrigo=20Mart=C3=ADn?= <contact@rodrigomartin.dev>
Date: Thu, 22 Aug 2024 23:30:22 +0200
Subject: [PATCH] feat: Expand ByteBuffer (#7316)

Co-authored-by: clydebarrow <2366188+clydebarrow@users.noreply.github.com>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
---
 esphome/core/bytebuffer.cpp | 225 +++++++++++++++++++++---------------
 esphome/core/bytebuffer.h   |  90 +++++++++++----
 2 files changed, 201 insertions(+), 114 deletions(-)

diff --git a/esphome/core/bytebuffer.cpp b/esphome/core/bytebuffer.cpp
index fb2ade3166..65525ecfcf 100644
--- a/esphome/core/bytebuffer.cpp
+++ b/esphome/core/bytebuffer.cpp
@@ -1,19 +1,64 @@
 #include "bytebuffer.h"
 #include <cassert>
+#include <cstring>
 
 namespace esphome {
 
-ByteBuffer ByteBuffer::create(size_t capacity) {
-  std::vector<uint8_t> data(capacity);
-  return {data};
-}
-
-ByteBuffer ByteBuffer::wrap(uint8_t *ptr, size_t len) {
+ByteBuffer ByteBuffer::wrap(const uint8_t *ptr, size_t len, Endian endianness) {
+  // there is a double copy happening here, could be optimized but at cost of clarity.
   std::vector<uint8_t> data(ptr, ptr + len);
-  return {data};
+  ByteBuffer buffer = {data};
+  buffer.endianness_ = endianness;
+  return buffer;
 }
 
-ByteBuffer ByteBuffer::wrap(std::vector<uint8_t> data) { return {std::move(data)}; }
+ByteBuffer ByteBuffer::wrap(std::vector<uint8_t> const &data, Endian endianness) {
+  ByteBuffer buffer = {data};
+  buffer.endianness_ = endianness;
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(uint8_t value) {
+  ByteBuffer buffer = ByteBuffer(1);
+  buffer.put_uint8(value);
+  buffer.flip();
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(uint16_t value, Endian endianness) {
+  ByteBuffer buffer = ByteBuffer(2, endianness);
+  buffer.put_uint16(value);
+  buffer.flip();
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(uint32_t value, Endian endianness) {
+  ByteBuffer buffer = ByteBuffer(4, endianness);
+  buffer.put_uint32(value);
+  buffer.flip();
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(uint64_t value, Endian endianness) {
+  ByteBuffer buffer = ByteBuffer(8, endianness);
+  buffer.put_uint64(value);
+  buffer.flip();
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(float value, Endian endianness) {
+  ByteBuffer buffer = ByteBuffer(sizeof(float), endianness);
+  buffer.put_float(value);
+  buffer.flip();
+  return buffer;
+}
+
+ByteBuffer ByteBuffer::wrap(double value, Endian endianness) {
+  ByteBuffer buffer = ByteBuffer(sizeof(double), endianness);
+  buffer.put_double(value);
+  buffer.flip();
+  return buffer;
+}
 
 void ByteBuffer::set_limit(size_t limit) {
   assert(limit <= this->get_capacity());
@@ -27,108 +72,102 @@ void ByteBuffer::clear() {
   this->limit_ = this->get_capacity();
   this->position_ = 0;
 }
-uint16_t ByteBuffer::get_uint16() {
-  assert(this->get_remaining() >= 2);
-  uint16_t value;
-  if (endianness_ == LITTLE) {
-    value = this->data_[this->position_++];
-    value |= this->data_[this->position_++] << 8;
-  } else {
-    value = this->data_[this->position_++] << 8;
-    value |= this->data_[this->position_++];
-  }
-  return value;
+void ByteBuffer::flip() {
+  this->limit_ = this->position_;
+  this->position_ = 0;
 }
 
-uint32_t ByteBuffer::get_uint32() {
-  assert(this->get_remaining() >= 4);
-  uint32_t value;
-  if (endianness_ == LITTLE) {
-    value = this->data_[this->position_++];
-    value |= this->data_[this->position_++] << 8;
-    value |= this->data_[this->position_++] << 16;
-    value |= this->data_[this->position_++] << 24;
-  } else {
-    value = this->data_[this->position_++] << 24;
-    value |= this->data_[this->position_++] << 16;
-    value |= this->data_[this->position_++] << 8;
-    value |= this->data_[this->position_++];
-  }
-  return value;
-}
-uint32_t ByteBuffer::get_uint24() {
-  assert(this->get_remaining() >= 3);
-  uint32_t value;
-  if (endianness_ == LITTLE) {
-    value = this->data_[this->position_++];
-    value |= this->data_[this->position_++] << 8;
-    value |= this->data_[this->position_++] << 16;
-  } else {
-    value = this->data_[this->position_++] << 16;
-    value |= this->data_[this->position_++] << 8;
-    value |= this->data_[this->position_++];
-  }
-  return value;
-}
-uint32_t ByteBuffer::get_int24() {
-  auto value = this->get_uint24();
-  uint32_t mask = (~(uint32_t) 0) << 23;
-  if ((value & mask) != 0)
-    value |= mask;
-  return value;
-}
+/// Getters
 uint8_t ByteBuffer::get_uint8() {
   assert(this->get_remaining() >= 1);
   return this->data_[this->position_++];
 }
-float ByteBuffer::get_float() {
-  auto value = this->get_uint32();
-  return *(float *) &value;
+uint64_t ByteBuffer::get_uint(size_t length) {
+  assert(this->get_remaining() >= length);
+  uint64_t value = 0;
+  if (this->endianness_ == LITTLE) {
+    this->position_ += length;
+    auto index = this->position_;
+    while (length-- != 0) {
+      value <<= 8;
+      value |= this->data_[--index];
+    }
+  } else {
+    while (length-- != 0) {
+      value <<= 8;
+      value |= this->data_[this->position_++];
+    }
+  }
+  return value;
 }
+
+uint32_t ByteBuffer::get_int24() {
+  auto value = this->get_uint24();
+  uint32_t mask = (~static_cast<uint32_t>(0)) << 23;
+  if ((value & mask) != 0)
+    value |= mask;
+  return value;
+}
+float ByteBuffer::get_float() {
+  assert(this->get_remaining() >= sizeof(float));
+  auto ui_value = this->get_uint32();
+  float value;
+  memcpy(&value, &ui_value, sizeof(float));
+  return value;
+}
+double ByteBuffer::get_double() {
+  assert(this->get_remaining() >= sizeof(double));
+  auto ui_value = this->get_uint64();
+  double value;
+  memcpy(&value, &ui_value, sizeof(double));
+  return value;
+}
+std::vector<uint8_t> ByteBuffer::get_vector(size_t length) {
+  assert(this->get_remaining() >= length);
+  auto start = this->data_.begin() + this->position_;
+  this->position_ += length;
+  return {start, start + length};
+}
+
+/// Putters
 void ByteBuffer::put_uint8(uint8_t value) {
   assert(this->get_remaining() >= 1);
   this->data_[this->position_++] = value;
 }
 
-void ByteBuffer::put_uint16(uint16_t value) {
-  assert(this->get_remaining() >= 2);
+void ByteBuffer::put_uint(uint64_t value, size_t length) {
+  assert(this->get_remaining() >= length);
   if (this->endianness_ == LITTLE) {
-    this->data_[this->position_++] = (uint8_t) value;
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
+    while (length-- != 0) {
+      this->data_[this->position_++] = static_cast<uint8_t>(value);
+      value >>= 8;
+    }
   } else {
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
-    this->data_[this->position_++] = (uint8_t) value;
+    this->position_ += length;
+    auto index = this->position_;
+    while (length-- != 0) {
+      this->data_[--index] = static_cast<uint8_t>(value);
+      value >>= 8;
+    }
   }
 }
-void ByteBuffer::put_uint24(uint32_t value) {
-  assert(this->get_remaining() >= 3);
-  if (this->endianness_ == LITTLE) {
-    this->data_[this->position_++] = (uint8_t) value;
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
-    this->data_[this->position_++] = (uint8_t) (value >> 16);
-  } else {
-    this->data_[this->position_++] = (uint8_t) (value >> 16);
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
-    this->data_[this->position_++] = (uint8_t) value;
-  }
+void ByteBuffer::put_float(float value) {
+  static_assert(sizeof(float) == sizeof(uint32_t), "Float sizes other than 32 bit not supported");
+  assert(this->get_remaining() >= sizeof(float));
+  uint32_t ui_value;
+  memcpy(&ui_value, &value, sizeof(float));  // this work-around required to silence compiler warnings
+  this->put_uint32(ui_value);
 }
-void ByteBuffer::put_uint32(uint32_t value) {
-  assert(this->get_remaining() >= 4);
-  if (this->endianness_ == LITTLE) {
-    this->data_[this->position_++] = (uint8_t) value;
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
-    this->data_[this->position_++] = (uint8_t) (value >> 16);
-    this->data_[this->position_++] = (uint8_t) (value >> 24);
-  } else {
-    this->data_[this->position_++] = (uint8_t) (value >> 24);
-    this->data_[this->position_++] = (uint8_t) (value >> 16);
-    this->data_[this->position_++] = (uint8_t) (value >> 8);
-    this->data_[this->position_++] = (uint8_t) value;
-  }
+void ByteBuffer::put_double(double value) {
+  static_assert(sizeof(double) == sizeof(uint64_t), "Double sizes other than 64 bit not supported");
+  assert(this->get_remaining() >= sizeof(double));
+  uint64_t ui_value;
+  memcpy(&ui_value, &value, sizeof(double));
+  this->put_uint64(ui_value);
 }
-void ByteBuffer::put_float(float value) { this->put_uint32(*(uint32_t *) &value); }
-void ByteBuffer::flip() {
-  this->limit_ = this->position_;
-  this->position_ = 0;
+void ByteBuffer::put_vector(const std::vector<uint8_t> &value) {
+  assert(this->get_remaining() >= value.size());
+  std::copy(value.begin(), value.end(), this->data_.begin() + this->position_);
+  this->position_ += value.size();
 }
 }  // namespace esphome
diff --git a/esphome/core/bytebuffer.h b/esphome/core/bytebuffer.h
index f242e5e333..d44d01f275 100644
--- a/esphome/core/bytebuffer.h
+++ b/esphome/core/bytebuffer.h
@@ -15,55 +15,103 @@ enum Endian { LITTLE, BIG };
  *
  * There are three variables maintained pointing into the buffer:
  *
- * 0 <= position <= limit <= capacity
- *
- * capacity: the maximum amount of data that can be stored
+ * capacity: the maximum amount of data that can be stored - set on construction and cannot be changed
  * limit: the limit of the data currently available to get or put
  * position: the current insert or extract position
  *
+ * 0 <= position <= limit <= capacity
+ *
  * In addition a mark can be set to the current position with mark(). A subsequent call to reset() will restore
  * the position to the mark.
  *
  * The buffer can be marked to be little-endian (default) or big-endian. All subsequent operations will use that order.
  *
+ * The flip() operation will reset the position to 0 and limit to the current position. This is useful for reading
+ * data from a buffer after it has been written.
+ *
  */
 class ByteBuffer {
  public:
+  // Default constructor (compatibility with TEMPLATABLE_VALUE)
+  ByteBuffer() : ByteBuffer(std::vector<uint8_t>()) {}
   /**
    * Create a new Bytebuffer with the given capacity
    */
-  static ByteBuffer create(size_t capacity);
+  ByteBuffer(size_t capacity, Endian endianness = LITTLE)
+      : data_(std::vector<uint8_t>(capacity)), endianness_(endianness), limit_(capacity){};
   /**
-   * Wrap an existing vector in a Bytebufffer
+   * Wrap an existing vector in a ByteBufffer
    */
-  static ByteBuffer wrap(std::vector<uint8_t> data);
+  static ByteBuffer wrap(std::vector<uint8_t> const &data, Endian endianness = LITTLE);
   /**
-   * Wrap an existing array in a Bytebufffer
+   * Wrap an existing array in a ByteBuffer. Note that this will create a copy of the data.
    */
-  static ByteBuffer wrap(uint8_t *ptr, size_t len);
+  static ByteBuffer wrap(const uint8_t *ptr, size_t len, Endian endianness = LITTLE);
+  // Convenience functions to create a ByteBuffer from a value
+  static ByteBuffer wrap(uint8_t value);
+  static ByteBuffer wrap(uint16_t value, Endian endianness = LITTLE);
+  static ByteBuffer wrap(uint32_t value, Endian endianness = LITTLE);
+  static ByteBuffer wrap(uint64_t value, Endian endianness = LITTLE);
+  static ByteBuffer wrap(int8_t value) { return wrap(static_cast<uint8_t>(value)); }
+  static ByteBuffer wrap(int16_t value, Endian endianness = LITTLE) {
+    return wrap(static_cast<uint16_t>(value), endianness);
+  }
+  static ByteBuffer wrap(int32_t value, Endian endianness = LITTLE) {
+    return wrap(static_cast<uint32_t>(value), endianness);
+  }
+  static ByteBuffer wrap(int64_t value, Endian endianness = LITTLE) {
+    return wrap(static_cast<uint64_t>(value), endianness);
+  }
+  static ByteBuffer wrap(float value, Endian endianness = LITTLE);
+  static ByteBuffer wrap(double value, Endian endianness = LITTLE);
+  static ByteBuffer wrap(bool value) { return wrap(static_cast<uint8_t>(value)); }
 
+  // Get an integral value from the buffer, increment position by length
+  uint64_t get_uint(size_t length);
   // Get one byte from the buffer, increment position by 1
   uint8_t get_uint8();
   // Get a 16 bit unsigned value, increment by 2
-  uint16_t get_uint16();
+  uint16_t get_uint16() { return static_cast<uint16_t>(this->get_uint(sizeof(uint16_t))); };
   // Get a 24 bit unsigned value, increment by 3
-  uint32_t get_uint24();
+  uint32_t get_uint24() { return static_cast<uint32_t>(this->get_uint(3)); };
   // Get a 32 bit unsigned value, increment by 4
-  uint32_t get_uint32();
-  // signed versions of the get functions
-  uint8_t get_int8() { return (int8_t) this->get_uint8(); };
-  int16_t get_int16() { return (int16_t) this->get_uint16(); }
+  uint32_t get_uint32() { return static_cast<uint32_t>(this->get_uint(sizeof(uint32_t))); };
+  // Get a 64 bit unsigned value, increment by 8
+  uint64_t get_uint64() { return this->get_uint(sizeof(uint64_t)); };
+  // Signed versions of the get functions
+  uint8_t get_int8() { return static_cast<int8_t>(this->get_uint8()); };
+  int16_t get_int16() { return static_cast<int16_t>(this->get_uint(sizeof(int16_t))); }
   uint32_t get_int24();
-  int32_t get_int32() { return (int32_t) this->get_uint32(); }
+  int32_t get_int32() { return static_cast<int32_t>(this->get_uint(sizeof(int32_t))); }
+  int64_t get_int64() { return static_cast<int64_t>(this->get_uint(sizeof(int64_t))); }
   // Get a float value, increment by 4
   float get_float();
+  // Get a double value, increment by 8
+  double get_double();
+  // Get a bool value, increment by 1
+  bool get_bool() { return this->get_uint8(); }
+  // Get vector of bytes, increment by length
+  std::vector<uint8_t> get_vector(size_t length);
 
-  // put values into the buffer, increment the position accordingly
+  // Put values into the buffer, increment the position accordingly
+  // put any integral value, length represents the number of bytes
+  void put_uint(uint64_t value, size_t length);
   void put_uint8(uint8_t value);
-  void put_uint16(uint16_t value);
-  void put_uint24(uint32_t value);
-  void put_uint32(uint32_t value);
+  void put_uint16(uint16_t value) { this->put_uint(value, sizeof(uint16_t)); }
+  void put_uint24(uint32_t value) { this->put_uint(value, 3); }
+  void put_uint32(uint32_t value) { this->put_uint(value, sizeof(uint32_t)); }
+  void put_uint64(uint64_t value) { this->put_uint(value, sizeof(uint64_t)); }
+  // Signed versions of the put functions
+  void put_int8(int8_t value) { this->put_uint8(static_cast<uint8_t>(value)); }
+  void put_int16(int32_t value) { this->put_uint(static_cast<uint16_t>(value), sizeof(uint16_t)); }
+  void put_int24(int32_t value) { this->put_uint(static_cast<uint32_t>(value), 3); }
+  void put_int32(int32_t value) { this->put_uint(static_cast<uint32_t>(value), sizeof(uint32_t)); }
+  void put_int64(int64_t value) { this->put_uint(static_cast<uint64_t>(value), sizeof(uint64_t)); }
+  // Extra put functions
   void put_float(float value);
+  void put_double(double value);
+  void put_bool(bool value) { this->put_uint8(value); }
+  void put_vector(const std::vector<uint8_t> &value);
 
   inline size_t get_capacity() const { return this->data_.size(); }
   inline size_t get_position() const { return this->position_; }
@@ -80,12 +128,12 @@ class ByteBuffer {
   // set limit to current position, postition to zero. Used when swapping from write to read operations.
   void flip();
   // retrieve a pointer to the underlying data.
-  uint8_t *array() { return this->data_.data(); };
+  std::vector<uint8_t> get_data() { return this->data_; };
   void rewind() { this->position_ = 0; }
   void reset() { this->position_ = this->mark_; }
 
  protected:
-  ByteBuffer(std::vector<uint8_t> data) : data_(std::move(data)) { this->limit_ = this->get_capacity(); }
+  ByteBuffer(std::vector<uint8_t> const &data) : data_(data), limit_(data.size()) {}
   std::vector<uint8_t> data_;
   Endian endianness_{LITTLE};
   size_t position_{0};