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// legacy dump data format.
package dump
import (
"fmt"
"github.com/mumax/3/data"
"github.com/mumax/3/util"
"hash"
"hash/crc64"
"io"
"math"
"os"
"unsafe"
)
func Read(in io.Reader) (*data.Slice, data.Meta, error) {
r := newReader(in)
return r.readSlice()
}
func ReadFile(fname string) (*data.Slice, data.Meta, error) {
f, err := os.Open(fname)
if err != nil {
return nil, data.Meta{}, err
}
defer f.Close()
return Read(f)
}
func MustReadFile(fname string) (*data.Slice, data.Meta) {
s, t, err := ReadFile(fname)
util.FatalErr(err)
return s, t
}
// Reads successive data frames in dump format.
type reader struct {
in io.Reader
crc hash.Hash64
err error
}
func newReader(in io.Reader) *reader {
r := new(reader)
r.in = in
r.crc = crc64.New(table)
return r
}
func (r *reader) readSlice() (s *data.Slice, info data.Meta, err error) {
r.err = nil // clear previous error, if any
magic := r.readString()
if r.err != nil {
return nil, data.Meta{}, r.err
}
if magic != MAGIC {
r.err = fmt.Errorf("dump: bad magic number:%v", magic)
return nil, data.Meta{}, r.err
}
nComp := r.readInt()
size := [3]int{}
size[2] = r.readInt() // backwards compatible coordinates!
size[1] = r.readInt()
size[0] = r.readInt()
cell := [3]float64{}
cell[2] = r.readFloat64()
cell[1] = r.readFloat64()
cell[0] = r.readFloat64()
info.CellSize = cell
info.MeshUnit = r.readString()
info.Time = r.readFloat64()
_ = r.readString() // time unit
s = data.NewSlice(nComp, size)
info.Name = r.readString()
info.Unit = r.readString()
precission := r.readUint64()
util.AssertMsg(precission == 4, "only single precission supported")
if r.err != nil {
return
}
host := s.Tensors()
ncomp := s.NComp()
for c := 0; c < ncomp; c++ {
for iz := 0; iz < size[2]; iz++ {
for iy := 0; iy < size[1]; iy++ {
for ix := 0; ix < size[0]; ix++ {
host[c][iz][iy][ix] = r.readFloat32()
}
}
}
}
// Check CRC
var mycrc uint64 // checksum by this reader
if r.crc != nil {
mycrc = r.crc.Sum64()
}
storedcrc := r.readUint64() // checksum from data stream. 0 means not set
if r.err != nil {
return nil, data.Meta{}, r.err
}
if r.crc != nil {
r.crc.Reset() // reset for next frame
}
if r.crc != nil && storedcrc != 0 && mycrc != storedcrc {
r.err = fmt.Errorf("dump CRC error: expected %16x, got %16x", storedcrc, mycrc)
return nil, data.Meta{}, r.err
}
return s, info, nil
}
func (r *reader) readInt() int {
x := r.readUint64()
if uint64(int(x)) != x {
r.err = fmt.Errorf("value overflows int: %v", x)
}
return int(x)
}
// read until the buffer is full
func (r *reader) read(buf []byte) {
_, err := io.ReadFull(r.in, buf[:])
if err != nil {
r.err = err
}
if r.crc != nil {
r.crc.Write(buf)
}
}
// read a maximum 8-byte string
func (r *reader) readString() string {
var buf [8]byte
r.read(buf[:])
// trim trailing NULs.
i := 0
for i = 0; i < len(buf); i++ {
if buf[i] == 0 {
break
}
}
return string(buf[:i])
}
func (r *reader) readFloat64() float64 {
return math.Float64frombits(r.readUint64())
}
func (r *reader) readUint64() uint64 {
var buf [8]byte
r.read(buf[:])
return *((*uint64)(unsafe.Pointer(&buf[0])))
}
func (r *reader) readFloat32() float32 {
var buf [4]byte
r.read(buf[:])
return *((*float32)(unsafe.Pointer(&buf[0])))
}
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