[GitHub] [doris] HappenLee commented on a diff in pull request #14946: [function](round) compute accurate round value by decimal

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

HappenLee commented on code in PR #14946:
URL: https://github.com/apache/doris/pull/14946#discussion_r1045367400


##########
be/src/vec/functions/round.h:
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@@ -0,0 +1,555 @@
+// 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.
+// This file is copied from
+// https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/FunctionRound.h
+// and modified by Doris
+
+#pragma once
+
+#ifdef __SSE4_1__
+#include <smmintrin.h>
+#else
+#include <fenv.h>
+#endif
+
+#include "vec/columns/column.h"
+#include "vec/columns/column_decimal.h"
+#include "vec/data_types/data_type_decimal.h"
+#include "vec/data_types/data_type_number.h"
+
+namespace doris::vectorized {
+
+enum class ScaleMode {
+    Positive, // round to a number with N decimal places after the decimal point
+    Negative, // round to an integer with N zero characters
+    Zero,     // round to an integer
+};
+
+enum class RoundingMode {
+#ifdef __SSE4_1__
+    Round = _MM_FROUND_TO_NEAREST_INT | _MM_FROUND_NO_EXC,
+    Floor = _MM_FROUND_TO_NEG_INF | _MM_FROUND_NO_EXC,
+    Ceil = _MM_FROUND_TO_POS_INF | _MM_FROUND_NO_EXC,
+    Trunc = _MM_FROUND_TO_ZERO | _MM_FROUND_NO_EXC,
+#else
+    Round = 8, /// Values are correspond to above just in case.
+    Floor = 9,
+    Ceil = 10,
+    Trunc = 11,
+#endif
+};
+
+enum class TieBreakingMode {
+    Auto,    // use banker's rounding for floating point numbers, round up otherwise
+    Bankers, // use banker's rounding
+};
+
+template <typename T, RoundingMode rounding_mode, ScaleMode scale_mode,
+          TieBreakingMode tie_breaking_mode>
+struct IntegerRoundingComputation {
+    static const size_t data_count = 1;
+
+    static size_t prepare(size_t scale) { return scale; }
+
+    /// Integer overflow is Ok.
+    static ALWAYS_INLINE T computeImpl(T x, T scale) {

Review Comment:
   `compute_impl`



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