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- package bbolt
-
- import (
- "reflect"
- "unsafe"
- )
-
- func unsafeAdd(base unsafe.Pointer, offset uintptr) unsafe.Pointer {
- return unsafe.Pointer(uintptr(base) + offset)
- }
-
- func unsafeIndex(base unsafe.Pointer, offset uintptr, elemsz uintptr, n int) unsafe.Pointer {
- return unsafe.Pointer(uintptr(base) + offset + uintptr(n)*elemsz)
- }
-
- func unsafeByteSlice(base unsafe.Pointer, offset uintptr, i, j int) []byte {
- // See: https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
- //
- // This memory is not allocated from C, but it is unmanaged by Go's
- // garbage collector and should behave similarly, and the compiler
- // should produce similar code. Note that this conversion allows a
- // subslice to begin after the base address, with an optional offset,
- // while the URL above does not cover this case and only slices from
- // index 0. However, the wiki never says that the address must be to
- // the beginning of a C allocation (or even that malloc was used at
- // all), so this is believed to be correct.
- return (*[maxAllocSize]byte)(unsafeAdd(base, offset))[i:j:j]
- }
-
- // unsafeSlice modifies the data, len, and cap of a slice variable pointed to by
- // the slice parameter. This helper should be used over other direct
- // manipulation of reflect.SliceHeader to prevent misuse, namely, converting
- // from reflect.SliceHeader to a Go slice type.
- func unsafeSlice(slice, data unsafe.Pointer, len int) {
- s := (*reflect.SliceHeader)(slice)
- s.Data = uintptr(data)
- s.Cap = len
- s.Len = len
- }
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