Finished readers (theoretically)

low/data/reader.go

@@ -1 +1,60 @@
 package data
+
+import "io"
+
+type Reader struct {
+	f         *FullReader
+	curBlock  []byte
+	nextIdx   uint32
+	curOffset uint32
+}
+
+func NewReader(f *FullReader) (Reader, error) {
+	dat, err := f.Block(0)
+	if err != nil {
+		return Reader{}, err
+	}
+	return Reader{
+		f:         f,
+		curBlock:  dat,
+		nextIdx:   1,
+		curOffset: 0,
+	}, nil
+}
+
+func (d *Reader) Close() error {
+	d.curBlock = nil
+	return nil
+}
+
+func (d *Reader) advanceBlock() error {
+	if d.nextIdx >= d.f.BlockNum() {
+		d.curBlock = nil
+		return io.EOF
+	}
+	var err error
+	d.curBlock, err = d.f.Block(d.nextIdx)
+	if err != nil {
+		return err
+	}
+	d.nextIdx++
+	d.curOffset = 0
+	return nil
+}
+
+func (d *Reader) Read(buf []byte) (int, error) {
+	totRed := 0
+	toRead := 0
+	var err error
+	for totRed < len(buf) {
+		if int(d.curOffset) >= len(d.curBlock) {
+			err = d.advanceBlock()
+			if err != nil {
+				return totRed, err
+			}
+		}
+		toRead = min(len(d.curBlock)-int(d.curOffset), len(buf)-totRed)
+		copy(buf[totRed:], d.curBlock[d.curOffset:d.curOffset+uint32(toRead)])
+	}
+	return totRed, nil
+}