93 lines
1.6 KiB
C++
93 lines
1.6 KiB
C++
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class TextFile {
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public:
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unsigned size() const;
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unsigned read(void *buffer, unsigned size, unsigned offset);
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private:
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static unsigned decodeBlock(uint8_t *in, unsigned inSize, uint8_t *out);
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unsigned _size;
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std::vector<unsigned> _pageSize
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};
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unsigned decodeBlock(uint8_t *in, unsigned inSize, uint8_t *out)
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{
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const unsigned DLE = 16;
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unsigned size = 0;
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for (unsigned i = 0; i < inSize; ++i)
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{
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uint8_t c = in[i];
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if (!c) break;
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if ((c == DLE) && (i + 1 < inSize))
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{
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unsigned x = in[++i] - 32;
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if (out)
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{
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for (unsigned i = 0; i < x; ++i)
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*out++ = ' ';
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}
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size += x;
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}
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else
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{
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if (out) *out++ = c;
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++size;
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}
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}
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return size;
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}
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{
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// first 2 blocks are header information
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_fileSize = 0;
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unsigned pages = (_endBlock - _startBlock - 2) >> 1
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uint8_t buffer[1024];
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unsigned offset = 0;
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for (unsigned i _startBlock + 2; i <= _endBlock; i += 2)
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{
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uint8_t buffer[1024];
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unsigned dataSize = 0;
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unsigned offset = 0;
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unsigned size;
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// load a 2-block page.
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for (j = i; j <= _endBlock; ++j)
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{
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_device->readBlock(j, buffer + offset);
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dataSize += j == _endBlock ? _lastByte : 512;
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}
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size = decodeBlock(buffer, dataSize, NULL);
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_pageSize.push_back(size);
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_fileSize += size;
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}
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}
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