150 lines
3.1 KiB
Go
150 lines
3.1 KiB
Go
package convert
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import (
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"bytes"
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"encoding/binary"
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"encoding/json"
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"fmt"
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"io"
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"io/fs"
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"slices"
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"github.com/d4l3k/go-bfloat16"
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"github.com/x448/float16"
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"golang.org/x/exp/maps"
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)
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type safetensorMetadata struct {
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Type string `json:"dtype"`
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Shape []uint64 `json:"shape"`
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Offsets []int64 `json:"data_offsets"`
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}
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func parseSafetensors(fsys fs.FS, ps ...string) ([]Tensor, error) {
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var ts []Tensor
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for _, p := range ps {
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f, err := fsys.Open(p)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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var n int64
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if err := binary.Read(f, binary.LittleEndian, &n); err != nil {
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return nil, err
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}
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b := bytes.NewBuffer(make([]byte, 0, n))
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if _, err = io.CopyN(b, f, n); err != nil {
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return nil, err
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}
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var headers map[string]safetensorMetadata
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if err := json.NewDecoder(b).Decode(&headers); err != nil {
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return nil, err
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}
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keys := maps.Keys(headers)
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slices.Sort(keys)
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for _, key := range keys {
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if value := headers[key]; value.Type != "" {
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ts = append(ts, safetensor{
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fs: fsys,
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path: p,
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dtype: value.Type,
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offset: safetensorsPad(n, value.Offsets[0]),
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size: safetensorsPad(n, value.Offsets[1]) - safetensorsPad(n, value.Offsets[0]),
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tensorBase: &tensorBase{
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name: key,
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shape: value.Shape,
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},
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})
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}
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}
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}
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return ts, nil
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}
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// safetensorsPad returns the padded size of the safetensors file given a length n and offset s
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func safetensorsPad(n, offset int64) int64 {
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return 8 + n + offset
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}
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type safetensor struct {
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fs fs.FS
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path string
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dtype string
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offset int64
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size int64
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*tensorBase
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}
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func (st safetensor) WriteTo(w io.Writer) (int64, error) {
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f, err := st.fs.Open(st.path)
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if err != nil {
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return 0, err
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}
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defer f.Close()
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if seeker, ok := f.(io.Seeker); ok {
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if _, err := seeker.Seek(st.offset, io.SeekStart); err != nil {
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return 0, err
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}
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} else {
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if _, err := io.CopyN(io.Discard, f, st.offset); err != nil {
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return 0, err
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}
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}
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var f32s []float32
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switch st.dtype {
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case "F32":
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f32s = make([]float32, st.size/4)
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if err = binary.Read(f, binary.LittleEndian, f32s); err != nil {
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return 0, err
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}
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case "F16":
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u16s := make([]uint16, st.size/2)
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if err = binary.Read(f, binary.LittleEndian, u16s); err != nil {
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return 0, err
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}
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f32s = make([]float32, len(u16s))
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for i := range u16s {
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f32s[i] = float16.Frombits(u16s[i]).Float32()
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}
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case "BF16":
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u8s := make([]uint8, st.size)
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if err = binary.Read(f, binary.LittleEndian, u8s); err != nil {
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return 0, err
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}
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f32s = bfloat16.DecodeFloat32(u8s)
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default:
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return 0, fmt.Errorf("unknown data type: %s", st.dtype)
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}
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if st.repacker != nil {
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f32s, err = st.repacker(st.Name(), f32s, st.Shape())
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if err != nil {
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return 0, err
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}
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}
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switch st.Kind() {
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case tensorKindF32:
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return 0, binary.Write(w, binary.LittleEndian, f32s)
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case tensorKindF16:
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f16s := make([]uint16, len(f32s))
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for i := range f32s {
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f16s[i] = float16.Fromfloat32(f32s[i]).Bits()
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}
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return 0, binary.Write(w, binary.LittleEndian, f16s)
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default:
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return 0, fmt.Errorf("unknown storage type: %d", st.Kind())
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}
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}
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