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116 lines
2.5 KiB
C++
116 lines
2.5 KiB
C++
#include <algorithm>
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#include "filestream.hpp"
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#include "excepts.hpp"
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namespace lazperf
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{
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OutFileStream::OutFileStream(std::ostream& out) : f_(out)
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{}
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// Should probably write to memory to avoid all these calls to a file that can't
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// be seen by the compiler.
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void OutFileStream::putBytes(const unsigned char *c, size_t len)
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{
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f_.write(reinterpret_cast<const char *>(c), len);
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}
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OutputCb OutFileStream::cb()
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{
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using namespace std::placeholders;
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return std::bind(&OutFileStream::putBytes, this, _1, _2);
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}
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// InFileStream
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struct InFileStream::Private
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{
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// Setting the offset_ to the buffer size will force a fill on the first read.
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Private(std::istream& in) : f_(in)
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{ reset(); }
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void getBytes(unsigned char *buf, size_t request);
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size_t fillit();
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void reset()
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{
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buf_.resize(1 << 20);
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offset_ = buf_.size();
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}
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std::istream& f_;
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std::vector<unsigned char> buf_;
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size_t offset_;
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};
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InFileStream::InFileStream(std::istream& in) : p_(new Private(in))
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{}
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InFileStream::~InFileStream()
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{}
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// This will force a fill on the next fetch.
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void InFileStream::reset()
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{
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p_->reset();
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}
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InputCb InFileStream::cb()
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{
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using namespace std::placeholders;
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return std::bind(&InFileStream::Private::getBytes, p_.get(), _1, _2);
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}
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void InFileStream::Private::getBytes(unsigned char *buf, size_t request)
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{
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// Almost all requests are size 1.
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if (request == 1)
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{
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if (offset_ >= buf_.size())
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fillit();
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*buf = buf_[offset_++];
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return;
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}
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size_t available = buf_.size() - offset_;
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if (request <= available)
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{
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unsigned char *begin = buf_.data() + offset_;
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unsigned char *end = begin + request;
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std::copy(begin, end, buf);
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offset_ += request;
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}
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else
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{
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do
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{
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size_t bytes = (std::min)(request, available);
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unsigned char *begin = buf_.data() + offset_;
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unsigned char *end = begin + bytes;
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std::copy(begin, end, buf);
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offset_ += bytes;
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request -= bytes;
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if (request == 0)
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break;
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buf += bytes;
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available = fillit();
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} while (true);
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}
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}
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size_t InFileStream::Private::fillit()
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{
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offset_ = 0;
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f_.read(reinterpret_cast<char *>(buf_.data()), buf_.size());
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size_t filled = f_.gcount();
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if (filled == 0)
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throw error("Unexpected end of file.");
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buf_.resize(filled);
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return filled;
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}
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} // namespace lazperf
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