func rdint64(f *obj.Biobuf) int64 {
r := f.Reader()
uv := uint64(0)
for shift := uint(0); ; shift += 7 {
if shift >= 64 {
log.Fatalf("corrupt input")
}
c, err := r.ReadByte()
if err != nil {
log.Fatalln("error reading input: ", err)
}
uv |= uint64(c&0x7F) << shift
if c&0x80 == 0 {
break
}
}
return int64(uv>>1) ^ (int64(uint64(uv)<<63) >> 63)
}
