github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/bitree/bdb/unsafe.go (about)

     1  // Copyright 2021 The Bitalosdb author(hustxrb@163.com) and other contributors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package bdb
    16  
    17  import (
    18  	"reflect"
    19  	"unsafe"
    20  )
    21  
    22  func unsafeAdd(base unsafe.Pointer, offset uintptr) unsafe.Pointer {
    23  	return unsafe.Pointer(uintptr(base) + offset)
    24  }
    25  
    26  func unsafeIndex(base unsafe.Pointer, offset uintptr, elemsz uintptr, n int) unsafe.Pointer {
    27  	return unsafe.Pointer(uintptr(base) + offset + uintptr(n)*elemsz)
    28  }
    29  
    30  func unsafeByteSlice(base unsafe.Pointer, offset uintptr, i, j int) []byte {
    31  	return (*[maxAllocSize]byte)(unsafeAdd(base, offset))[i:j:j]
    32  }
    33  
    34  func unsafeSlice(slice, data unsafe.Pointer, len int) {
    35  	s := (*reflect.SliceHeader)(slice)
    36  	s.Data = uintptr(data)
    37  	s.Cap = len
    38  	s.Len = len
    39  }