How to convert CPointer lt ByteVar gt to Int Value I try it reinterpret lt IntVar gt pointed value but did t work

there are unsafe casts between `CPointer lt T gt ` and `Long` available provided by ` toLong ` and ` toCPointer lt T gt ` extension methods `val longValue = ptr toLong ` `val originalPtr = longValue toCPointer lt T gt `

`ptr toLong ` is C ` int ptr` `val toCPointer lt T gt ` is C ` T val`

I get val value = PQgetvalue res j i value CPointer lt ByteVar gt

I write on Kotlin val val = PQgetvalue res j i let val result = ntohl it reinterpret lt IntVar gt pointed value n result 0

or ntohl it reinterpret lt IntVar gt 0

How to convert CPointer lt ByteVar gt to Int Value I try it kotlinlang #kotlin-native

Channels

kotlin-multiplatform-contest

osgi

brikk

revolver

tricity-kotlin-user-group

cincinnati-user-group

prozis-android-backup

refactoring-to-kotlin

russian-kotlinasfirst

androidgithubprojects

navigation-architecture-component

stayhungrystayfoolish

practical-functional-programming

tensorflow

swagger-gradle-codegen

kotlinultimatechallenge

competitive-programming

skia-wasm-interop-temp

java-to-kotlin-refactoring

event21-community-content

myndocs-oauth2-server

jvm-ir-backend-feedback

Title

levcom

11/18/2017, 8:37 PM

How to convert CPointer<ByteVar>? to Int Value/ I try it.reinterpret<IntVar>().pointed.value, but did't work

msink

11/18/2017, 10:51 PM

there are unsafe casts between

CPointer<T>?

and

Long

available, provided by

.toLong()

and

.toCPointer<T>()

extension methods:

val longValue = ptr.toLong()

val originalPtr = longValue.toCPointer<T>()

levcom

11/19/2017, 8:27 AM

I think, need to convert the binary value (in CPointer<T>?) to the reverse order byte (from network byte order to local byte order), and then unsafe casts CPointer<T>? to <IntVar>. But I don't understand how Kotlin/Native support binary types.

msink

11/19/2017, 10:31 AM

ptr.toLong()

is C

(int)ptr

val.toCPointer<T>

is C

(T*)val

if you want not pointer itself but value it points to, then better do something like

val ipaddr = (ptr[0] << 24) or (ptr[1] << 16) or (ptr[3] << 8) or (ptr[3])

olonho

11/20/2017, 5:41 AM

What exactly are trying to achieve?

if you really need byte order conversion, take a look at https://github.com/JetBrains/kotlin-native/blob/master/samples/socket/src/main/kotlin/EchoServer.kt#L43

levcom

11/20/2017, 10:51 PM

I get: val value = PQgetvalue(res, j, i) (value : CPointer<ByteVar>?)

I want (on С lang.): val = ntohl(\*((uint32_t \*) value))

I write on Kotlin: val val = PQgetvalue(res, j, i)?.let { val result = ntohl(it.reinterpret<IntVar>().pointed.value) \n result } ?: 0

or "ntohl(it.reinterpret<IntVar>()[0])"

But I don't get right value

msink

11/21/2017, 1:31 AM

*((u32*)value)

is bad idea - not portable, works only on x86 if not aligned on x4 boundary linux kernel have macro

get_unaligned_be32

and similar, implemented by byte reads and shifts.

levcom

11/24/2017, 6:48 PM

Thank you all for your help! I studied examples EchoServer.kt and other ex. with native C-functions. I use ntohl/htonl functions from package platform.posix.*

14 Views

#kotlin-native Join Slack