Implement ByteBuffer (#6878)

esphome/core/bytebuffer.cpp

@@ -0,0 +1,134 @@
+#include "bytebuffer.h"
+#include <cassert>
+
+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) {
+  std::vector<uint8_t> data(ptr, ptr + len);
+  return {data};
+}
+
+ByteBuffer ByteBuffer::wrap(std::vector<uint8_t> data) { return {std::move(data)}; }
+
+void ByteBuffer::set_limit(size_t limit) {
+  assert(limit <= this->get_capacity());
+  this->limit_ = limit;
+}
+void ByteBuffer::set_position(size_t position) {
+  assert(position <= this->get_limit());
+  this->position_ = position;
+}
+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;
+}
+
+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;
+}
+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;
+}
+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);
+  if (this->endianness_ == LITTLE) {
+    this->data_[this->position_++] = (uint8_t) value;
+    this->data_[this->position_++] = (uint8_t) (value >> 8);
+  } else {
+    this->data_[this->position_++] = (uint8_t) (value >> 8);
+    this->data_[this->position_++] = (uint8_t) value;
+  }
+}
+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_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_float(float value) { this->put_uint32(*(uint32_t *) &value); }
+void ByteBuffer::flip() {
+  this->limit_ = this->position_;
+  this->position_ = 0;
+}
+}  // namespace esphome

esphome/core/bytebuffer.h

@@ -0,0 +1,96 @@
+#pragma once
+
+#include <utility>
+#include <vector>
+#include <cinttypes>
+#include <cstddef>
+
+namespace esphome {
+
+enum Endian { LITTLE, BIG };
+
+/**
+ * A class modelled on the Java ByteBuffer class. It wraps a vector of bytes and permits putting and getting
+ * items of various sizes, with an automatically incremented position.
+ *
+ * There are three variables maintained pointing into the buffer:
+ *
+ * 0 <= position <= limit <= capacity
+ *
+ * capacity: the maximum amount of data that can be stored
+ * limit: the limit of the data currently available to get or put
+ * position: the current insert or extract position
+ *
+ * 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.
+ *
+ */
+class ByteBuffer {
+ public:
+  /**
+   * Create a new Bytebuffer with the given capacity
+   */
+  static ByteBuffer create(size_t capacity);
+  /**
+   * Wrap an existing vector in a Bytebufffer
+   */
+  static ByteBuffer wrap(std::vector<uint8_t> data);
+  /**
+   * Wrap an existing array in a Bytebufffer
+   */
+  static ByteBuffer wrap(uint8_t *ptr, size_t len);
+
+  // 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();
+  // Get a 24 bit unsigned value, increment by 3
+  uint32_t get_uint24();
+  // 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_int24();
+  int32_t get_int32() { return (int32_t) this->get_uint32(); }
+  // Get a float value, increment by 4
+  float get_float();
+
+  // put values into the buffer, increment the position accordingly
+  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_float(float value);
+
+  inline size_t get_capacity() const { return this->data_.size(); }
+  inline size_t get_position() const { return this->position_; }
+  inline size_t get_limit() const { return this->limit_; }
+  inline size_t get_remaining() const { return this->get_limit() - this->get_position(); }
+  inline Endian get_endianness() const { return this->endianness_; }
+  inline void mark() { this->mark_ = this->position_; }
+  inline void big_endian() { this->endianness_ = BIG; }
+  inline void little_endian() { this->endianness_ = LITTLE; }
+  void set_limit(size_t limit);
+  void set_position(size_t position);
+  // set position to 0, limit to capacity.
+  void clear();
+  // 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(); };
+  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(); }
+  std::vector<uint8_t> data_;
+  Endian endianness_{LITTLE};
+  size_t position_{0};
+  size_t mark_{0};
+  size_t limit_{0};
+};
+
+}  // namespace esphome