gguf : add support for I64 and F64 arrays (#6062)

* gguf : add support for I64 and F64 arrays

GGML currently does not support I64 or F64 arrays and they are not often
used in machine learning, however if in the future the need arises, it
would be nice to add them now, so that the types are next to the other
types I8, I16, I32 in the enums, and it also reserves their type number.

Furthermore, with this addition the GGUF format becomes very usable for
most computational applications of NumPy (being compatible with the most
common NumPy dtypes: i8, i16, i32, i64, f32, f64), providing a faster,
and more versatile alternative to the `npz` format, and a simpler
alternative to the `hdf5` format.

The change in this PR seems small, not significantly increasing the
maintenance burden. I tested this from Python using GGUFWriter/Reader
and `gguf-dump`, as well as from C, everything seems to work.

* Fix compiler warnings

3 files changed, 21 insertions, 7 deletions

diff --git a/gguf-py/gguf/constants.py b/gguf-py/gguf/constants.py
index 2d7cf16c..458a641d 100644
--- a/gguf-py/gguf/constants.py
+++ b/gguf-py/gguf/constants.py
@@ -665,6 +665,8 @@ class GGMLQuantizationType(IntEnum):
     I8      = 24
     I16     = 25
     I32     = 26
+    I64     = 27
+    F64     = 28
 
 
 class GGUFEndian(IntEnum):
@@ -734,6 +736,8 @@ GGML_QUANT_SIZES = {
     GGMLQuantizationType.I8:      (1, 1),
     GGMLQuantizationType.I16:     (1, 2),
     GGMLQuantizationType.I32:     (1, 4),
+    GGMLQuantizationType.I64:     (1, 8),
+    GGMLQuantizationType.F64:     (1, 8),
 }
 
 
diff --git a/gguf-py/gguf/gguf_reader.py b/gguf-py/gguf/gguf_reader.py
index 1c10f575..33afac55 100644
--- a/gguf-py/gguf/gguf_reader.py
+++ b/gguf-py/gguf/gguf_reader.py
@@ -242,12 +242,15 @@ class GGUFReader:
             n_bytes = n_elems * type_size // block_size
             data_offs = int(start_offs + offset_tensor[0])
             item_type: npt.DTypeLike
-            if ggml_type == GGMLQuantizationType.F32:
+            if ggml_type == GGMLQuantizationType.F16:
+                item_count = n_elems
+                item_type = np.float16
+            elif ggml_type == GGMLQuantizationType.F32:
                 item_count = n_elems
                 item_type = np.float32
-            elif ggml_type == GGMLQuantizationType.F16:
+            elif ggml_type == GGMLQuantizationType.F64:
                 item_count = n_elems
-                item_type = np.float16
+                item_type = np.float64
             elif ggml_type == GGMLQuantizationType.I8:
                 item_count = n_elems
                 item_type = np.int8
@@ -257,6 +260,9 @@ class GGUFReader:
             elif ggml_type == GGMLQuantizationType.I32:
                 item_count = n_elems
                 item_type = np.int32
+            elif ggml_type == GGMLQuantizationType.I64:
+                item_count = n_elems
+                item_type = np.int64
             else:
                 item_count = n_bytes
                 item_type = np.uint8
diff --git a/gguf-py/gguf/gguf_writer.py b/gguf-py/gguf/gguf_writer.py
index 81b2eb88..1967b633 100644
--- a/gguf-py/gguf/gguf_writer.py
+++ b/gguf-py/gguf/gguf_writer.py
@@ -204,18 +204,22 @@ class GGUFWriter:
         for i in range(n_dims):
             self.ti_data += self._pack("Q", tensor_shape[n_dims - 1 - i])
         if raw_dtype is None:
-            if tensor_dtype == np.float32:
-                dtype = GGMLQuantizationType.F32
-            elif tensor_dtype == np.float16:
+            if tensor_dtype == np.float16:
                 dtype = GGMLQuantizationType.F16
+            elif tensor_dtype == np.float32:
+                dtype = GGMLQuantizationType.F32
+            elif tensor_dtype == np.float64:
+                dtype = GGMLQuantizationType.F64
             elif tensor_dtype == np.int8:
                 dtype = GGMLQuantizationType.I8
             elif tensor_dtype == np.int16:
                 dtype = GGMLQuantizationType.I16
             elif tensor_dtype == np.int32:
                 dtype = GGMLQuantizationType.I32
+            elif tensor_dtype == np.int64:
+                dtype = GGMLQuantizationType.I64
             else:
-                raise ValueError("Only F32, F16, I8, I16, I32 tensors are supported for now")
+                raise ValueError("Only F16, F32, F64, I8, I16, I32, I64 tensors are supported for now")
         else:
             dtype = raw_dtype
         self.ti_data += self._pack("I", dtype)