68 lines
1.8 KiB
C++
68 lines
1.8 KiB
C++
/**
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******************************************************************************
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* Xenia : Xbox 360 Emulator Research Project *
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******************************************************************************
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* Copyright 2015 Ben Vanik. All rights reserved. *
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* Released under the BSD license - see LICENSE in the root for more details. *
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******************************************************************************
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*/
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#include "xenia/base/ring_buffer.h"
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#include <cstring>
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namespace xe {
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RingBuffer::RingBuffer(uint8_t *raw_buffer, size_t size, size_t write_offset)
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: raw_buffer_(raw_buffer),
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size_(size),
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write_offset_(write_offset) {}
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size_t RingBuffer::Write(uint8_t *buffer, size_t num_bytes) {
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size_t bytes_written = 0;
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size_t input_offset = 0;
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size_t bytes_to_write = 0;
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// write offset -> end
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bytes_to_write =
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num_bytes < size_ - write_offset_ ? num_bytes : size_ - write_offset_;
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std::memcpy(raw_buffer_ + write_offset_, buffer, bytes_to_write);
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input_offset = bytes_to_write;
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write_offset_ += bytes_to_write;
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bytes_written += bytes_to_write;
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// Wraparound (begin -> num_bytes)
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if (input_offset < num_bytes) {
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bytes_to_write = num_bytes - input_offset;
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std::memcpy(raw_buffer_, buffer + input_offset, bytes_to_write);
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write_offset_ = bytes_to_write;
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bytes_written += bytes_to_write;
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}
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return bytes_written;
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}
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size_t RingBuffer::DistanceToOffset(size_t offset) {
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// Make sure the offset is in range.
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if (offset > size_) {
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offset %= size_;
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}
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if (offset < size_ && offset >= write_offset_) {
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// Doesn't wraparound.
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return offset - write_offset_;
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} else {
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// Wraparound.
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size_t dist = size_ - write_offset_;
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dist += offset;
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return dist;
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}
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}
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} // namespace xe
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