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