suchagit commented on a change in pull request #9356: URL: https://github.com/apache/arrow/pull/9356#discussion_r585730554
########## File path: csharp/src/Apache.Arrow/DecimalUtility.cs ########## @@ -0,0 +1,163 @@ +// 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. + +using System; +using System.Linq; +using System.Numerics; +using System.Runtime.InteropServices; + +namespace Apache.Arrow +{ + /// <summary> + /// This is semi-optimised best attempt at converting to / from decimal and the buffers + /// </summary> + internal static class DecimalUtility + { + private static readonly BigInteger _maxDecimal = new BigInteger(decimal.MaxValue); + private static readonly BigInteger _minDecimal = new BigInteger(decimal.MinValue); + private static readonly ulong[] s_powersOfTen = + { + 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 10000000000, 100000000000, + 1000000000000, 10000000000000, 100000000000000, 1000000000000000, 10000000000000000, 100000000000000000, + 1000000000000000000, 10000000000000000000 + }; + private static int PowersOfTenLength => s_powersOfTen.Length - 1; + + public static decimal GetDecimal(in ArrowBuffer valueBuffer, int index, int scale, int byteWidth, + bool isUnsigned = false) + { + int startIndex = index * byteWidth; + ReadOnlySpan<byte> value = valueBuffer.Span.Slice(startIndex, byteWidth); + BigInteger integerValue; + +#if NETCOREAPP + integerValue = new BigInteger(value); +#else + integerValue = new BigInteger(value.ToArray()); +#endif + + if (integerValue > _maxDecimal || integerValue < _minDecimal) + { + BigInteger scaleBy = BigInteger.Pow(10, scale); + BigInteger integerPart = BigInteger.DivRem(integerValue, scaleBy, out BigInteger fractionalPart); + if (integerPart > _maxDecimal || integerPart < _minDecimal) // decimal overflow, not much we can do here - C# needs a BigDecimal + { + throw new OverflowException("Value: " + integerPart + " too big or too small to be represented as a decimal"); + } + return (decimal)integerPart + DivideByScale(fractionalPart, scale); + } + else + { + return DivideByScale(integerValue, scale); + } + } + + private static decimal DivideByScale(BigInteger integerValue, int scale) + { + decimal result = (decimal)integerValue; // this cast is safe here + int drop = scale; + while (drop > PowersOfTenLength) + { + result /= s_powersOfTen[PowersOfTenLength]; + drop -= PowersOfTenLength; + } + + result /= s_powersOfTen[drop]; + return result; + } + + public static void GetBytes(BigInteger integerValue, int byteWidth, ref Span<byte> bytes) + { + if (bytes.Length != byteWidth) + { + throw new OverflowException("ValueBuffer size not equal to " + byteWidth + " byte width: " + bytes.Length); + } + + Span<byte> integerBytes = integerValue.ToByteArray().AsSpan(); + if (integerBytes.Length > byteWidth) + { + throw new OverflowException("Decimal size greater than " + byteWidth + " bytes: " + integerBytes.Length); + } + + if (integerBytes.Length == byteWidth) + { + bytes = integerBytes; + return; + } + + if (integerValue.Sign == -1) + { + integerBytes.CopyTo(bytes); + for (int i = integerBytes.Length; i < byteWidth; i++) + { + bytes[i] = 255; + } + } + else + { + integerBytes.CopyTo(bytes); + } + } + + public static bool CheckPrecisionAndScale(decimal value, int precision, int scale, out BigInteger integerValue) + { + DecimalLayout layout = new DecimalLayout(value); // use in place of decimal.GetBits(value) to avoid an allocation + integerValue = new BigInteger(BitConverter.GetBytes(layout.Lo).Concat(BitConverter.GetBytes(layout.Mid)).Concat(BitConverter.GetBytes(layout.Hi)).ToArray()); + + if (layout.Scale > scale) + throw new OverflowException("Decimal scale can not be greater than that in the Arrow vector: " + layout.Scale + " != " + scale); Review comment: Added ########## File path: csharp/src/Apache.Arrow/DecimalUtility.cs ########## @@ -0,0 +1,163 @@ +// 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. + +using System; +using System.Linq; +using System.Numerics; +using System.Runtime.InteropServices; + +namespace Apache.Arrow +{ + /// <summary> + /// This is semi-optimised best attempt at converting to / from decimal and the buffers + /// </summary> + internal static class DecimalUtility + { + private static readonly BigInteger _maxDecimal = new BigInteger(decimal.MaxValue); + private static readonly BigInteger _minDecimal = new BigInteger(decimal.MinValue); + private static readonly ulong[] s_powersOfTen = + { + 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 10000000000, 100000000000, + 1000000000000, 10000000000000, 100000000000000, 1000000000000000, 10000000000000000, 100000000000000000, + 1000000000000000000, 10000000000000000000 + }; + private static int PowersOfTenLength => s_powersOfTen.Length - 1; + + public static decimal GetDecimal(in ArrowBuffer valueBuffer, int index, int scale, int byteWidth, + bool isUnsigned = false) + { + int startIndex = index * byteWidth; + ReadOnlySpan<byte> value = valueBuffer.Span.Slice(startIndex, byteWidth); + BigInteger integerValue; + +#if NETCOREAPP + integerValue = new BigInteger(value); +#else + integerValue = new BigInteger(value.ToArray()); +#endif + + if (integerValue > _maxDecimal || integerValue < _minDecimal) + { + BigInteger scaleBy = BigInteger.Pow(10, scale); + BigInteger integerPart = BigInteger.DivRem(integerValue, scaleBy, out BigInteger fractionalPart); + if (integerPart > _maxDecimal || integerPart < _minDecimal) // decimal overflow, not much we can do here - C# needs a BigDecimal + { + throw new OverflowException("Value: " + integerPart + " too big or too small to be represented as a decimal"); + } + return (decimal)integerPart + DivideByScale(fractionalPart, scale); + } + else + { + return DivideByScale(integerValue, scale); + } + } + + private static decimal DivideByScale(BigInteger integerValue, int scale) + { + decimal result = (decimal)integerValue; // this cast is safe here + int drop = scale; + while (drop > PowersOfTenLength) + { + result /= s_powersOfTen[PowersOfTenLength]; + drop -= PowersOfTenLength; + } + + result /= s_powersOfTen[drop]; + return result; + } + + public static void GetBytes(BigInteger integerValue, int byteWidth, ref Span<byte> bytes) + { + if (bytes.Length != byteWidth) + { + throw new OverflowException("ValueBuffer size not equal to " + byteWidth + " byte width: " + bytes.Length); + } + + Span<byte> integerBytes = integerValue.ToByteArray().AsSpan(); + if (integerBytes.Length > byteWidth) + { + throw new OverflowException("Decimal size greater than " + byteWidth + " bytes: " + integerBytes.Length); + } + + if (integerBytes.Length == byteWidth) + { + bytes = integerBytes; + return; + } + + if (integerValue.Sign == -1) + { + integerBytes.CopyTo(bytes); + for (int i = integerBytes.Length; i < byteWidth; i++) + { + bytes[i] = 255; + } + } + else + { + integerBytes.CopyTo(bytes); + } + } + + public static bool CheckPrecisionAndScale(decimal value, int precision, int scale, out BigInteger integerValue) + { + DecimalLayout layout = new DecimalLayout(value); // use in place of decimal.GetBits(value) to avoid an allocation + integerValue = new BigInteger(BitConverter.GetBytes(layout.Lo).Concat(BitConverter.GetBytes(layout.Mid)).Concat(BitConverter.GetBytes(layout.Hi)).ToArray()); + + if (layout.Scale > scale) + throw new OverflowException("Decimal scale can not be greater than that in the Arrow vector: " + layout.Scale + " != " + scale); + + if(integerValue >= BigInteger.Pow(10, precision)) + throw new OverflowException("Decimal precision can not be greater than that in the Arrow vector: " + value + " has precision > " + precision); + + if (layout.Scale < scale) // pad with trailing zeros + { + integerValue *= BigInteger.Pow(10, scale - layout.Scale); + } + + if (value < 0) // sign the big int + integerValue = -integerValue; + + return true; + } + + [StructLayout(LayoutKind.Explicit)] + private readonly struct DecimalLayout + { + public DecimalLayout(decimal value) + { + this = default; + d = value; + } + + [FieldOffset(0)] private readonly decimal d; + + [FieldOffset(0)] private readonly int flags; + [FieldOffset(4)] private readonly int hi; +#if BIGENDIAN Review comment: I've removed this as part of the latest refactor ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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