added common examples

examples/common/idxio.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+
+#######################################################
+# Copyright (c) 2024, ArrayFire
+# All rights reserved.
+#
+# This file is distributed under 3-clause BSD license.
+# The complete license agreement can be obtained at:
+# http://arrayfire.com/licenses/BSD-3-Clause
+########################################################
+
+
+def reverse_char(b):
+    b = (b & 0xF0) >> 4 | (b & 0x0F) << 4
+    b = (b & 0xCC) >> 2 | (b & 0x33) << 2
+    b = (b & 0xAA) >> 1 | (b & 0x55) << 1
+    return b
+
+
+# http://stackoverflow.com/a/9144870/2192361
+def reverse(x):
+    x = ((x >> 1) & 0x55555555) | ((x & 0x55555555) << 1)
+    x = ((x >> 2) & 0x33333333) | ((x & 0x33333333) << 2)
+    x = ((x >> 4) & 0x0F0F0F0F) | ((x & 0x0F0F0F0F) << 4)
+    x = ((x >> 8) & 0x00FF00FF) | ((x & 0x00FF00FF) << 8)
+    x = ((x >> 16) & 0xFFFF) | ((x & 0xFFFF) << 16)
+    return x
+
+
+def read_idx(name):
+    with open(name, "rb") as f:
+        # In the C++ version, bytes the size of 4 chars are being read
+        # May not work properly in machines where a char is not 1 byte
+        bytes_read = f.read(4)
+        bytes_read = bytearray(bytes_read)
+
+        if bytes_read[2] != 8:
+            raise RuntimeError("Unsupported data type")
+
+        numdims = bytes_read[3]
+        elemsize = 1
+
+        # Read the dimensions
+        elem = 1
+        dims = [0] * numdims
+        for i in range(numdims):
+            bytes_read = bytearray(f.read(4))
+
+            # Big endian to little endian
+            for j in range(4):
+                bytes_read[j] = reverse_char(bytes_read[j])
+            bytes_read_int = int.from_bytes(bytes_read, "little")
+            dim = reverse(bytes_read_int)
+
+            elem = elem * dim
+            dims[i] = dim
+
+        # Read the data
+        cdata = f.read(elem * elemsize)
+        cdata = list(cdata)
+        data = [float(cdata_elem) for cdata_elem in cdata]
+
+        return (dims, data)
+
+
+if __name__ == "__main__":
+    # Example usage of reverse_char
+    byte_value = 0b10101010
+    reversed_byte = reverse_char(byte_value)
+    print(f"Original byte: {byte_value:08b}, Reversed byte: {reversed_byte:08b}")
+
+    # Example usage of reverse
+    int_value = 0x12345678
+    reversed_int = reverse(int_value)
+    print(f"Original int: {int_value:032b}, Reversed int: {reversed_int:032b}")