ardupilot/libraries/AP_HAL/utility/RingBuffer.h

306 lines
7.3 KiB
C++

#pragma once
#include <atomic>
#include <stdint.h>
/*
* Circular buffer of bytes.
*/
class ByteBuffer {
public:
ByteBuffer(uint32_t size);
~ByteBuffer(void);
// number of bytes available to be read
uint32_t available(void) const;
// Discards the buffer content, emptying it.
void clear(void);
// number of bytes space available to write
uint32_t space(void) const;
// true if available() is zero
bool empty(void) const;
// write bytes to ringbuffer. Returns number of bytes written
uint32_t write(const uint8_t *data, uint32_t len);
// read bytes from ringbuffer. Returns number of bytes read
uint32_t read(uint8_t *data, uint32_t len);
// read a byte from ring buffer. Returns true on success, false otherwise
bool read_byte(uint8_t *data);
/*
update bytes at the read pointer. Used to update an object without
popping it
*/
bool update(const uint8_t *data, uint32_t len);
// return size of ringbuffer
uint32_t get_size(void) const { return size; }
// set size of ringbuffer, caller responsible for locking
bool set_size(uint32_t size);
// advance the read pointer (discarding bytes)
bool advance(uint32_t n);
// Returns the pointer and size to a contiguous read of the next available data
const uint8_t *readptr(uint32_t &available_bytes);
// peek one byte without advancing read pointer. Return byte
// or -1 if none available
int16_t peek(uint32_t ofs) const;
/*
read len bytes without advancing the read pointer
*/
uint32_t peekbytes(uint8_t *data, uint32_t len);
// Similar to peekbytes(), but will fill out IoVec struct with
// both parts of the ring buffer if wraparound is happening, or
// just one part. Returns the number of parts written to.
struct IoVec {
uint8_t *data;
uint32_t len;
};
uint8_t peekiovec(IoVec vec[2], uint32_t len);
// Reserve `len` bytes and fills out `vec` with both parts of the
// ring buffer (if wraparound is happening), or just one contiguous
// part. Returns the number of `vec` elements filled out. Can be used
// with system calls such as `readv()`.
//
// After a call to 'reserve()', 'write()' should never be called
// until 'commit()' is called!
uint8_t reserve(IoVec vec[2], uint32_t len);
/*
* "Releases" the memory previously reserved by 'reserve()' to be read.
* Committer must inform how many bytes were actually written in 'len'.
*/
bool commit(uint32_t len);
private:
uint8_t *buf;
uint32_t size;
std::atomic<uint32_t> head{0}; // where to read data
std::atomic<uint32_t> tail{0}; // where to write data
};
/*
ring buffer class for objects of fixed size
*/
template <class T>
class ObjectBuffer {
public:
ObjectBuffer(uint32_t _size) {
buffer = new ByteBuffer((_size * sizeof(T))+1);
}
~ObjectBuffer(void) {
delete buffer;
}
// Discards the buffer content, emptying it.
void clear(void)
{
buffer->clear();
}
// return number of objects available to be read
uint32_t available(void) const {
return buffer->available() / sizeof(T);
}
// return number of objects that could be written
uint32_t space(void) const {
return buffer->space() / sizeof(T);
}
// true is available() == 0
bool empty(void) const {
return buffer->empty();
}
// push one object
bool push(const T &object) {
if (buffer->space() < sizeof(T)) {
return false;
}
return buffer->write((uint8_t*)&object, sizeof(T)) == sizeof(T);
}
/*
throw away an object
*/
bool pop(void) {
return buffer->advance(sizeof(T));
}
/*
pop earliest object off the queue
*/
bool pop(T &object) {
if (buffer->available() < sizeof(T)) {
return false;
}
return buffer->read((uint8_t*)&object, sizeof(T)) == sizeof(T);
}
/*
* push_force() is semantically equivalent to:
* if (!push(t)) { pop(); push(t); }
*/
bool push_force(const T &object) {
if (buffer->space() < sizeof(T)) {
buffer->advance(sizeof(T));
}
return push(object);
}
/*
peek copies an object out without advancing the read pointer
*/
bool peek(T &object) {
return buffer->peekbytes((uint8_t*)&object, sizeof(T)) == sizeof(T);
}
/* update the object at the front of the queue (the one that would
be fetched by pop()) */
bool update(const T &object) {
return buffer->update((uint8_t*)&object, sizeof(T));
}
private:
ByteBuffer *buffer = nullptr;
};
/*
ring buffer class for objects of fixed size with pointer
access. Note that this is not thread safe, buf offers efficient
array-like access
*/
template <class T>
class ObjectArray {
public:
ObjectArray(uint16_t _size) {
size = _size;
head = count = 0;
buffer = new T[size];
}
~ObjectArray(void) {
delete[] buffer;
}
// return number of objects available to be read
uint16_t available(void) const {
return count;
}
// return number of objects that could be written
uint16_t space(void) const {
return size - count;
}
// true is available() == 0
bool empty(void) const {
return count == 0;
}
// push one object
bool push(const T &object) {
if (space() == 0) {
return false;
}
buffer[(head+count)%size] = object;
count++;
return true;
}
/*
throw away an object
*/
bool pop(void) {
if (empty()) {
return false;
}
head = (head+1) % size;
count--;
return true;
}
// Discards the buffer content, emptying it.
void clear(void)
{
head = count = 0;
}
/*
pop earliest object off the queue
*/
bool pop(T &object) {
if (empty()) {
return false;
}
object = buffer[head];
return pop();
}
/*
* push_force() is semantically equivalent to:
* if (!push(t)) { pop(); push(t); }
*/
bool push_force(const T &object) {
if (space() == 0) {
pop();
}
return push(object);
}
/*
remove the Nth element from the array. First element is zero
*/
bool remove(uint16_t n) {
if (n >= count) {
return false;
}
if (n == count-1) {
// remove last element
count--;
return true;
}
if (n == 0) {
// remove first element
return pop();
}
// take advantage of the [] operator for simple shift of the array elements
for (uint16_t i=n; i<count-1; i++) {
*(*this)[i] = *(*this)[i+1];
}
count--;
return true;
}
// allow array indexing, based on current head. Returns a pointer
// to the object or nullptr
T * operator[](uint16_t i) {
if (i >= count) {
return nullptr;
}
return &buffer[(head+i)%size];
}
private:
T *buffer;
uint16_t size; // total buffer size
uint16_t count; // number in buffer now
uint16_t head; // first element
};