ceph/src/arrow/go/arrow/type_traits_decimal128.go

   1 // Licensed to the Apache Software Foundation (ASF) under one
   2 // or more contributor license agreements.  See the NOTICE file
   3 // distributed with this work for additional information
   4 // regarding copyright ownership.  The ASF licenses this file
   5 // to you under the Apache License, Version 2.0 (the
   6 // "License"); you may not use this file except in compliance
   7 // with the License.  You may obtain a copy of the License at
   8 //
   9 // http://www.apache.org/licenses/LICENSE-2.0
  10 //
  11 // Unless required by applicable law or agreed to in writing, software
  12 // distributed under the License is distributed on an "AS IS" BASIS,
  13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 // See the License for the specific language governing permissions and
  15 // limitations under the License.
  16
  17 package arrow
  18
  19 import (
  20         "reflect"
  21         "unsafe"
  22
  23         "github.com/apache/arrow/go/v6/arrow/decimal128"
  24         "github.com/apache/arrow/go/v6/arrow/endian"
  25 )
  26
  27 // Decimal128 traits
  28 var Decimal128Traits decimal128Traits
  29
  30 const (
  31         // Decimal128SizeBytes specifies the number of bytes required to store a single decimal128 in memory
  32         Decimal128SizeBytes = int(unsafe.Sizeof(decimal128.Num{}))
  33 )
  34
  35 type decimal128Traits struct{}
  36
  37 // BytesRequired returns the number of bytes required to store n elements in memory.
  38 func (decimal128Traits) BytesRequired(n int) int { return Decimal128SizeBytes * n }
  39
  40 // PutValue
  41 func (decimal128Traits) PutValue(b []byte, v decimal128.Num) {
  42         endian.Native.PutUint64(b[:8], uint64(v.LowBits()))
  43         endian.Native.PutUint64(b[8:], uint64(v.HighBits()))
  44 }
  45
  46 // CastFromBytes reinterprets the slice b to a slice of type uint16.
  47 //
  48 // NOTE: len(b) must be a multiple of Uint16SizeBytes.
  49 func (decimal128Traits) CastFromBytes(b []byte) []decimal128.Num {
  50         h := (*reflect.SliceHeader)(unsafe.Pointer(&b))
  51
  52         var res []decimal128.Num
  53         s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
  54         s.Data = h.Data
  55         s.Len = h.Len / Decimal128SizeBytes
  56         s.Cap = h.Cap / Decimal128SizeBytes
  57
  58         return res
  59 }
  60
  61 // CastToBytes reinterprets the slice b to a slice of bytes.
  62 func (decimal128Traits) CastToBytes(b []decimal128.Num) []byte {
  63         h := (*reflect.SliceHeader)(unsafe.Pointer(&b))
  64
  65         var res []byte
  66         s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
  67         s.Data = h.Data
  68         s.Len = h.Len * Decimal128SizeBytes
  69         s.Cap = h.Cap * Decimal128SizeBytes
  70
  71         return res
  72 }
  73
  74 // Copy copies src to dst.
  75 func (decimal128Traits) Copy(dst, src []decimal128.Num) { copy(dst, src) }