github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/internal/unsafe2/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 unsafe2
    16  
    17  import (
    18  	"unsafe"
    19  )
    20  
    21  const MaxAllocSize = 0xFFFFFFFFFFFF // 256TB
    22  
    23  func String(b []byte) string {
    24  	if len(b) == 0 {
    25  		return ""
    26  	}
    27  	return unsafe.String(&b[0], len(b))
    28  }
    29  
    30  func ByteSlice(s string) []byte {
    31  	return unsafe.Slice(unsafe.StringData(s), len(s))
    32  }
    33  
    34  func UnsafeAdd(base unsafe.Pointer, offset uintptr) unsafe.Pointer {
    35  	return unsafe.Pointer(uintptr(base) + offset)
    36  }
    37  
    38  func UnsafeIndex(base unsafe.Pointer, offset uintptr, elemsz uintptr, n int) unsafe.Pointer {
    39  	return unsafe.Pointer(uintptr(base) + offset + uintptr(n)*elemsz)
    40  }
    41  
    42  func UnsafeByteSlice(base unsafe.Pointer, offset uintptr, i, j int) []byte {
    43  	return (*[MaxAllocSize]byte)(UnsafeAdd(base, offset))[i:j:j]
    44  }