X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=blobdiff_plain;f=source%2Fio%2Fslice.cpp;fp=source%2Fio%2Fslice.cpp;h=423c1a6c8cae85e73c2f6e15e9733786b31d700e;hp=0000000000000000000000000000000000000000;hb=eedad559456b8e62ed3b9bd9e8253e5f8bcc02d6;hpb=1a6331551a025ddcc1772ae447c326ec70e0e107

diff --git a/source/io/slice.cpp b/source/io/slice.cpp
new file mode 100644
index 0000000..423c1a6
--- /dev/null
+++ b/source/io/slice.cpp
@@ -0,0 +1,111 @@
+#include <stdexcept>
+#include "slice.h"
+
+using namespace std;
+
+namespace Msp {
+namespace IO {
+
+Slice::Slice(Seekable &b, SeekOffset s, SeekOffset l):
+	below(b),
+	start_offset(s),
+	length(l),
+	position(0),
+	sync_position(true)
+{
+	if(s<0 || l<0)
+		throw invalid_argument("Slice");
+
+	mode = below.get_mode()&M_RDWR;
+	below.signal_flush_required.connect(sigc::mem_fun(this, &Slice::flush));
+}
+
+void Slice::flush()
+{
+	sync_position = true;
+}
+
+unsigned Slice::prepare_op(unsigned size, Mode m)
+{
+	check_access(m);
+
+	if(sync_position)
+		seek(position, S_BEG);
+
+	SeekOffset remaining = start_offset+length-position;
+	if(size>remaining)
+		size = remaining;
+	if(!size && m==M_READ)
+		set_eof();
+
+	return size;
+}
+
+unsigned Slice::do_write(const char *data, unsigned size)
+{
+	size = prepare_op(size, M_WRITE);
+	if(!size)
+		return 0;
+
+	unsigned len = below.write(data, size);
+	position += len;
+	return len;
+}
+
+unsigned Slice::do_read(char *data, unsigned size)
+{
+	size = prepare_op(size, M_READ);
+	if(!size)
+		return 0;
+
+	unsigned len = below.read(data, size);
+	if(!len && below.eof())
+		set_eof();
+	position += len;
+	return len;
+}
+
+unsigned Slice::put(char c)
+{
+	if(!prepare_op(1, M_WRITE))
+		return 0;
+
+	unsigned len = below.put(c);
+	position += len;
+	return len;
+}
+
+int Slice::get()
+{
+	if(!prepare_op(1, M_READ))
+		return 0;
+
+	int c = below.get();
+	if(c==-1 && below.eof())
+		set_eof();
+	else
+		++position;
+	return c;
+}
+
+SeekOffset Slice::seek(SeekOffset off, SeekType type)
+{
+	if(type==S_BEG)
+		off += start_offset;
+	else if(type==S_CUR)
+		off += position;
+	else if(type==S_END)
+		off += start_offset+length;
+
+	if(off<start_offset || off>start_offset+length)
+		throw bad_seek(off, type);
+
+	signal_flush_required.emit();
+
+	position = below.seek(off, S_BEG)-start_offset;
+	sync_position = false;
+	return position;
+}
+
+} // namespace IO
+} // namespace Msp