Thanks Michael,
Here is the cleaner current version, thanks to your suggestion:
//writeData loops over the field vectors and write their binary
representation to an io.Writer
func (sf *File) writeData(w io.Writer) error {
if sf.NoObs == 0 {
return nil
}
if len(sf.fields) == 0 {
return fmt.Errorf("No fields")
}
bs := make([]byte, sf.recordSize)
for i := int32(0); i < sf.NoObs; i++ {
offset := 0
for _, f := range sf.fields {
switch f.FieldType {
case StataByte:
v := f.data.([]int8)[i]
bs[offset] = byte(v)
offset++
case StataInt:
v := f.data.([]int16)[i]
bs[offset] = byte(v)
offset++ //incrementing the offset instead of using
bs[offset+1] to avoid doing the addition twice
bs[offset] = byte(v >> 8)
offset++
case StataLong:
v := f.data.([]int32)[i]
bs[offset] = byte(v)
offset++
bs[offset] = byte(v >> 8)
offset++
bs[offset] = byte(v >> 16)
offset++
bs[offset] = byte(v >> 24)
offset++
case StataFloat:
base := *(*[4]byte)(unsafe.Pointer(&f.data.([]float32)[i]))
copy(bs[offset:], base[:])
offset += 4
case StataDouble:
base := *(*[8]byte)(unsafe.Pointer(&f.data.([]float64)[i]))
copy(bs[offset:], base[:])
offset += 8
default:
return fmt.Errorf("Field type [%d] not supported in field %s
", f.FieldType, f.Name)
}
}
if _, err := w.Write(bs); err != nil {
return err
}
}
return nil
}
On Saturday, October 28, 2017 at 9:38:19 AM UTC-5, Michael Jones wrote:
>
> you could do your unsafe cast to an appropriately-sized byte array and
> write that as a single call or use it to access the bytes:
>
> base := *(*[8]byte)(unsafe.Pointer(&doubleThing))
> bs[offset+0]=base[0]
> bs[offset+1]=base[1]
> :
> offset+=8
>
>
>
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