Safetensor support (#215)

Co-authored-by: Awni Hannun <awni@apple.com>

mlx/io/load.cpp

@@ -0,0 +1,242 @@
+// Copyright © 2023 Apple Inc.
+
+#include <algorithm>
+#include <cstring>
+#include <fstream>
+#include <limits>
+#include <sstream>
+
+#include "mlx/io/load.h"
+#include "mlx/ops.h"
+#include "mlx/primitives.h"
+#include "mlx/utils.h"
+
+// Adapted from
+// https://github.com/angeloskath/supervised-lda/blob/master/include/ldaplusplus/NumpyFormat.hpp
+
+namespace mlx::core {
+
+namespace {
+
+static constexpr uint8_t MAGIC[] = {
+    0x93,
+    0x4e,
+    0x55,
+    0x4d,
+    0x50,
+    0x59,
+};
+
+inline bool is_big_endian_() {
+  union ByteOrder {
+    int32_t i;
+    uint8_t c[4];
+  };
+  ByteOrder b = {0x01234567};
+
+  return b.c[0] == 0x01;
+}
+
+} // namespace
+
+/** Save array to out stream in .npy format */
+void save(std::shared_ptr<io::Writer> out_stream, array a, bool retain_graph) {
+  ////////////////////////////////////////////////////////
+  // Check array
+
+  a.eval(retain_graph);
+
+  if (a.nbytes() == 0) {
+    throw std::invalid_argument("[save] cannot serialize an empty array");
+  }
+
+  if (!a.flags().contiguous) {
+    throw std::invalid_argument(
+        "[save] cannot serialize a non-contiguous array");
+  }
+
+  ////////////////////////////////////////////////////////
+  // Check file
+  if (!out_stream->good() || !out_stream->is_open()) {
+    throw std::runtime_error("[save] Failed to open " + out_stream->label());
+  }
+
+  ////////////////////////////////////////////////////////
+  // Prepare header
+  std::ostringstream magic_ver_len;
+  magic_ver_len.write(reinterpret_cast<const char*>(MAGIC), 6);
+
+  std::string fortran_order = a.flags().col_contiguous ? "True" : "False";
+  std::ostringstream header;
+  header << "{'descr': '" << dtype_to_array_protocol(a.dtype()) << "',"
+         << " 'fortran_order': " << fortran_order << ","
+         << " 'shape': (";
+  for (auto i : a.shape()) {
+    header << i << ", ";
+  }
+  header << ")}";
+
+  size_t header_len = static_cast<size_t>(header.tellp());
+  bool is_v1 = header_len + 15 < std::numeric_limits<uint16_t>::max();
+
+  // Pad out magic + version + header_len + header + \n to be divisible by 16
+  size_t padding = (6 + 2 + (2 + 2 * is_v1) + header_len + 1) % 16;
+
+  header << std::string(padding, ' ') << '\n';
+
+  if (is_v1) {
+    magic_ver_len << (char)0x01 << (char)0x00;
+
+    uint16_t v1_header_len = header.tellp();
+    const char* len_bytes = reinterpret_cast<const char*>(&v1_header_len);
+
+    if (!is_big_endian_()) {
+      magic_ver_len.write(len_bytes, 2);
+    } else {
+      magic_ver_len.write(len_bytes + 1, 1);
+      magic_ver_len.write(len_bytes, 1);
+    }
+  } else {
+    magic_ver_len << (char)0x02 << (char)0x00;
+
+    uint32_t v2_header_len = header.tellp();
+    const char* len_bytes = reinterpret_cast<const char*>(&v2_header_len);
+
+    if (!is_big_endian_()) {
+      magic_ver_len.write(len_bytes, 4);
+    } else {
+      magic_ver_len.write(len_bytes + 3, 1);
+      magic_ver_len.write(len_bytes + 2, 1);
+      magic_ver_len.write(len_bytes + 1, 1);
+      magic_ver_len.write(len_bytes, 1);
+    }
+  }
+  ////////////////////////////////////////////////////////
+  // Serialize array
+
+  out_stream->write(magic_ver_len.str().c_str(), magic_ver_len.str().length());
+  out_stream->write(header.str().c_str(), header.str().length());
+  out_stream->write(a.data<char>(), a.nbytes());
+
+  return;
+}
+
+/** Save array to file in .npy format */
+void save(const std::string& file_, array a, bool retain_graph) {
+  // Open and check file
+  std::string file = file_;
+
+  // Add .npy to file name if it is not there
+  if (file.length() < 4 || file.substr(file.length() - 4, 4) != ".npy")
+    file += ".npy";
+
+  // Serialize array
+  save(std::make_shared<io::FileWriter>(file), a, retain_graph);
+}
+
+/** Load array from reader in .npy format */
+array load(std::shared_ptr<io::Reader> in_stream, StreamOrDevice s) {
+  ////////////////////////////////////////////////////////
+  // Open and check file
+  if (!in_stream->good() || !in_stream->is_open()) {
+    throw std::runtime_error("[load] Failed to open " + in_stream->label());
+  }
+
+  ////////////////////////////////////////////////////////
+  // Read header and prepare array details
+
+  // Read and check magic
+  char read_magic_and_ver[8];
+  in_stream->read(read_magic_and_ver, 8);
+  if (std::memcmp(read_magic_and_ver, MAGIC, 6) != 0) {
+    throw std::runtime_error("[load] Invalid header in " + in_stream->label());
+  }
+
+  // Read and check version
+  if (read_magic_and_ver[6] != 1 && read_magic_and_ver[6] != 2) {
+    throw std::runtime_error(
+        "[load] Unsupport npy format version in " + in_stream->label());
+  }
+
+  // Read header len and header
+  int header_len_size = read_magic_and_ver[6] == 1 ? 2 : 4;
+  size_t header_len;
+
+  if (header_len_size == 2) {
+    uint16_t v1_header_len;
+    in_stream->read(reinterpret_cast<char*>(&v1_header_len), header_len_size);
+    header_len = v1_header_len;
+  } else {
+    uint32_t v2_header_len;
+    in_stream->read(reinterpret_cast<char*>(&v2_header_len), header_len_size);
+    header_len = v2_header_len;
+  }
+
+  // Read the header
+  std::vector<char> buffer(header_len + 1);
+  in_stream->read(&buffer[0], header_len);
+  buffer[header_len] = 0;
+  std::string header(&buffer[0]);
+
+  // Read data type from header
+  std::string dtype_str = header.substr(11, 3);
+  bool read_is_big_endian = dtype_str[0] == '>';
+  Dtype dtype = dtype_from_array_protocol(dtype_str);
+
+  // Read contiguity order
+  bool col_contiguous = header[34] == 'T';
+
+  // Read array shape from header
+  std::vector<int> shape;
+
+  size_t st = header.find_last_of('(') + 1;
+  size_t ed = header.find_last_of(')');
+  std::string shape_str = header.substr(st, ed - st);
+
+  while (!shape_str.empty()) {
+    // Read current number and get position of comma
+    size_t pos;
+    int dim = std::stoi(shape_str, &pos);
+    shape.push_back(dim);
+
+    // Skip the comma and space and read the next number
+    if (pos + 2 <= shape_str.length())
+      shape_str = shape_str.substr(pos + 2);
+    else {
+      shape_str = shape_str.substr(pos);
+      if (!shape_str.empty() && shape_str != " " && shape_str != ",") {
+        throw std::runtime_error(
+            "[load] Unknown error while parsing header in " +
+            in_stream->label());
+      }
+      shape_str = "";
+    }
+  }
+
+  ////////////////////////////////////////////////////////
+  // Build primitive
+
+  size_t offset = 8 + header_len_size + header.length();
+  bool swap_endianness = read_is_big_endian != is_big_endian_();
+
+  if (col_contiguous) {
+    std::reverse(shape.begin(), shape.end());
+  }
+  auto loaded_array = array(
+      shape,
+      dtype,
+      std::make_unique<Load>(to_stream(s), in_stream, offset, swap_endianness),
+      std::vector<array>{});
+  if (col_contiguous) {
+    loaded_array = transpose(loaded_array, s);
+  }
+
+  return loaded_array;
+}
+
+/** Load array from file in .npy format */
+array load(const std::string& file, StreamOrDevice s) {
+  return load(std::make_shared<io::FileReader>(file), s);
+}
+
+} // namespace mlx::core