TwoTerm/cpp/ring_buffer.h
Kelvin Sherlock 59487424bb fix warnings.
git-svn-id: svn://qnap.local/TwoTerm/branches/fix-gno-scrolling-region@3157 5590a31f-7b70-45f8-8c82-aa3a8e5f4507
2017-02-05 19:22:40 +00:00

119 lines
2.3 KiB
C++

//
// ring_buffer.h
// 2Term
//
// Created by Kelvin Sherlock on 1/25/2017.
//
//
#ifndef ring_buffer_h
#define ring_buffer_h
#include <stdint.h>
#include <assert.h>
template<size_t Size>
class ring_buffer {
static_assert((Size & ~(Size - 1)) == Size, "Size must be power of 2");
public:
void write(uint8_t x) {
_buffer[_ptr] = x;
_ptr = (_ptr + 1) & (Size-1);
if (_capacity) --_capacity;
}
void write(const uint8_t *data, size_t dsize) {
if (!dsize) return;
// simple replace.
if (dsize >= Size) {
_ptr = _capacity = 0;
memcpy(_buffer, data + dsize - Size, Size);
assert(_redzone == 0);
return;
}
// simple append.
if (_capacity >= dsize) {
memcpy(_buffer + _ptr, data, dsize);
_ptr = (_ptr + dsize) & (Size - 1);
_capacity -= dsize;
assert(_redzone == 0);
return;
}
// no capacity left.. overwrite.
// dsize < Size.
_capacity = 0;
// fill up the end, then wrap around to start.
if (_ptr + dsize > Size) {
size_t amt = Size - _ptr;
memcpy(_buffer + _ptr, data, amt);
_ptr = 0;
dsize -= amt;
data += amt;
}
if (dsize) {
memcpy(_buffer + _ptr, data, dsize);
_ptr = (_ptr + dsize) & (Size - 1);
}
assert(_redzone == 0);
}
std::vector<uint8_t> read() const {
std::vector<uint8_t> rv;
if (_capacity) {
rv.assign(_buffer, _buffer + _ptr);
return rv;
}
// _ptr ... end, 0 .. _ptr
rv.assign(_buffer + _ptr, _buffer + Size);
if (_ptr) rv.insert(rv.end(), _buffer, _buffer + _ptr);
return rv;
}
size_t max_size() const {
return Size;
}
size_t size() const {
return Size - _capacity;
}
bool empty() const {
return _capacity == Size;
}
void clear() {
_ptr = 0;
_capacity = Size;
}
private:
size_t _capacity = Size;
size_t _ptr = 0;
uint8_t _buffer[Size];
uint64_t _redzone = 0;
};
#endif /* ring_buffer_h */