[GitHub] [arrow] kiszk commented on a change in pull request #7940: ARROW-9702: [C++] Register bpacking SIMD to runtime path.

[GitBox <gi...@apache.org>]

kiszk commented on a change in pull request #7940:
URL: https://github.com/apache/arrow/pull/7940#discussion_r474672365



##########
File path: cpp/src/arrow/util/bpacking_avx2_codegen.py
##########
@@ -0,0 +1,200 @@
+#!/bin/python
+
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# Usage: python bpacking_avx2_codegen.py > bpacking_avx2_generated.h
+
+
+def print_unpack_bit_func(bit):
+    shift = 0
+    shifts = []
+    in_index = 0
+    inls = []
+    mask = (1 << bit) - 1
+    bracket = "{"
+
+    print(
+        f"inline static const uint32_t* unpack{bit}_32_avx2(const uint32_t* in, uint32_t* out) {bracket}")
+    print("  uint32_t mask = 0x%x;" % mask)
+    print("  __m256i reg_shifts, reg_inls, reg_masks;")
+    print("  __m256i results;")
+
+    print("")
+    for i in range(32):
+        if shift + bit == 32:
+            shifts.append(shift)
+            inls.append(f"in[{in_index}]")
+            in_index += 1
+            shift = 0
+        elif shift + bit > 32:  # croos the boundary

Review comment:
       nit: `croos` -> `cross`




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