Add ARM64/Apple Silicon architecture support

Enhance library loading to properly detect and support ARM64 architecture (M1+
Macs, ARM servers, modern Raspberry Pi). Replace platform.architecture() with
platform.machine() for accurate architecture detection.

Changes:
- Add arm64_path parameter to load_library() and find_library_path()
- Implement architecture-specific path mapping (x86, x86_64, arm64)
- Add smart fallback: arm64_path defaults to x64_path for universal binaries
- Add debug logging for architecture detection and path selection
- Update README with ARM64 examples and architecture support documentation
- Maintain full backward compatibility with existing code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ctoth

README.md

@@ -23,6 +23,9 @@ my_lib = load_library("mylibrary")
 # Load a library with custom paths for 32-bit and 64-bit versions
 my_lib = load_library("mylibrary", x86_path="./lib/x86", x64_path="./lib/x64")
 
+# Load a library with ARM64 support (M1+ Macs, ARM servers)
+my_lib = load_library("mylibrary", x64_path="./lib/x64", arm64_path="./lib/arm64")
+
 # Call a function from the library
 result = my_lib.some_function(arg1, arg2)
 ```
@@ -43,8 +46,8 @@ speech = load_com("SAPI.SpVoice", "SpeechLib.SpVoice")
 
 ### libloader
 
-* `load_library(library, x86_path=".", x64_path=".", *args, **kwargs)`: Load a library with the given name.
-* `find_library_path(libname, x86_path=".", x64_path=".")`: Finds the path of the given library.
+* `load_library(library, x86_path=".", x64_path=".", arm64_path=None, *args, **kwargs)`: Load a library with the given name. If `arm64_path` is not specified on ARM64 systems, falls back to `x64_path`.
+* `find_library_path(libname, x86_path=".", x64_path=".", arm64_path=None)`: Finds the path of the given library.
 * `get_functype()`: Returns the ctypes functype for the current platform.
 * `get_library_extension()`: Get the extension of the library for your current platform.
 * `_do_load(file, *args, **kwargs)`: Attempts to actually load the library. Used internally by load_library.
@@ -62,6 +65,16 @@ Libloader automatically handles the differences between platforms:
 * macOS: `.dylib` files
 * Linux: `.so` files
 
+### Architecture Support
+
+Libloader automatically detects the system architecture and loads the appropriate library:
+
+* **x86** (32-bit): Uses `x86_path`
+* **x86_64/AMD64** (64-bit Intel/AMD): Uses `x64_path`
+* **ARM64/aarch64** (M1+ Macs, ARM servers): Uses `arm64_path` if specified, otherwise falls back to `x64_path`
+
+This means existing code works on Apple Silicon Macs without modification, while allowing you to provide architecture-specific binaries when needed.
+
 ## License
 
 See the LICENSE file for details.

libloader/libloader.py

@@ -34,11 +34,16 @@ class LibraryLoadError(OSError):
     pass
 
 
-def load_library(library, x86_path=".", x64_path=".", *args, **kwargs):
+def load_library(library, x86_path=".", x64_path=".", arm64_path=None, *args, **kwargs):
     logger.debug("Attempting to load library: %s", library)
-    logger.debug("x86_path: %s, x64_path: %s", os.path.abspath(x86_path), os.path.abspath(x64_path))
-
-    lib = find_library_path(library, x86_path=x86_path, x64_path=x64_path)
+    logger.debug(
+        "x86_path: %s, x64_path: %s, arm64_path: %s",
+        os.path.abspath(x86_path),
+        os.path.abspath(x64_path),
+        os.path.abspath(arm64_path) if arm64_path is not None else None,
+    )
+
+    lib = find_library_path(library, x86_path=x86_path, x64_path=x64_path, arm64_path=arm64_path)
     logger.debug("Resolved library path: %s", lib)
 
     loaded = _do_load(lib, *args, **kwargs)
@@ -61,21 +66,34 @@ def _do_load(file, *args, **kwargs):
         return None
 
 
-def find_library_path(libname, x86_path=".", x64_path="."):
+def find_library_path(libname, x86_path=".", x64_path=".", arm64_path=None):
     system = platform.system()
     prefix = TYPES[system]["prefix"]
     libname_with_prefix = f"{prefix}{libname}"
     logger.debug("Library name with prefix: %s", libname_with_prefix)
 
-    arch = platform.architecture()[0]
-    logger.debug("Detected architecture: %s", arch)
-
-    if arch == "64bit":
+    # Get actual machine architecture
+    machine = platform.machine().lower()
+    logger.debug("Detected machine architecture: %s", machine)
+
+    # Map machine architecture to the appropriate path
+    if machine in ("arm64", "aarch64"):
+        # ARM64 architecture (M1+ Macs, ARM servers, modern Raspberry Pi)
+        if arm64_path is None:
+            logger.debug("ARM64 detected, arm64_path not specified, falling back to x64_path")
+            path = os.path.join(x64_path, libname_with_prefix)
+            logger.debug("Using fallback x64 path: %s", x64_path)
+        else:
+            path = os.path.join(arm64_path, libname_with_prefix)
+            logger.debug("Using ARM64 path: %s", arm64_path)
+    elif machine in ("x86_64", "amd64", "x64"):
+        # 64-bit x86 architecture (Intel/AMD)
         path = os.path.join(x64_path, libname_with_prefix)
-        logger.debug("Using 64-bit path: %s", x64_path)
+        logger.debug("Using x86_64 path: %s", x64_path)
     else:
+        # 32-bit x86 or other architectures
         path = os.path.join(x86_path, libname_with_prefix)
-        logger.debug("Using 32-bit path: %s", x86_path)
+        logger.debug("Using x86 path for architecture '%s': %s", machine, x86_path)
 
     ext = get_library_extension()
     logger.debug("Using library extension: %s", ext)