mirror of https://github.com/rusefi/rusefi.git
68 lines
1.6 KiB
C++
68 lines
1.6 KiB
C++
/**
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* @file buffered_writer.h
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*/
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#pragma once
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#include <cstring>
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struct Writer {
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virtual size_t write(const char* buffer, size_t count) = 0;
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virtual size_t flush() = 0;
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};
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template <int TBufferSize>
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class BufferedWriter : public Writer {
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public:
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size_t write(const char* buffer, size_t count) override {
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size_t bytesFlushed = 0;
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while (count) {
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if (m_bytesUsed == 0 && count >= TBufferSize) {
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// special case: write-thru, skip the copy
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bytesFlushed += writeInternal(buffer, count);
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count = 0;
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} else if (m_bytesUsed + count < TBufferSize) {
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// Write that will fit in the buffer, just copy to intermediate buffer
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memcpy(m_buffer + m_bytesUsed, buffer, count);
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m_bytesUsed += count;
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count = 0;
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} else {
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// Need to write partial, then flush buffer
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size_t bytesToWrite = TBufferSize - m_bytesUsed;
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// Copy this block in to place
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memcpy(m_buffer + m_bytesUsed, buffer, bytesToWrite);
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m_bytesUsed += bytesToWrite;
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// Flush to underlying
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bytesFlushed += flush();
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// Step the read pointer ahead
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buffer += bytesToWrite;
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// Decrement remaining bytes
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count -= bytesToWrite;
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}
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}
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return bytesFlushed;
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}
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// Flush the internal buffer to the underlying interface.
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size_t flush() override {
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size_t bytesToWrite = m_bytesUsed;
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if (bytesToWrite > 0) {
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m_bytesUsed = 0;
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return writeInternal(m_buffer, bytesToWrite);
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} else {
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return 0;
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}
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}
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protected:
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virtual size_t writeInternal(const char* buffer, size_t count) = 0;
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private:
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char m_buffer[TBufferSize];
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size_t m_bytesUsed = 0;
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};
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