profuse/pascal/TextFile.cpp

93 lines
1.6 KiB
C++

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