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how to convert const Uint8* to Uint8*


By : José Marques
Date : July 29 2020, 01:00 PM
I wish did fix the issue. You can use const_cast for this, e.g:
code :
Uint8* foo = const_cast<Uint8*>(bar);


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C# P-Invoke:how to convert INT fun( BYTE *bStream, UINT16 *nCount, const UINT8 nblk ) to C#?


By : Aurora
Date : March 29 2020, 07:55 AM
around this issue Your code which copies between the managed array, and the unmanaged pointer, is in the wrong place. It would need to be after the call to the unmanaged function.
But you may as well let the p/invoke marshaller do the work for you:
code :
[DllImport(@"C:\PrBioApi.dll")]
private static extern bool CmdGetAllLog(
    byte[] bStream, 
    ref ushort nCount, 
    byte nblk
);

int nMallocSize = ...;
byte[] pRecord = new byte[nMallocSize];
bool bGetSucc = CmdGetAllLog(pRecord, ref nGet, nBlk++);

Does converting UInt8(or similar types) to Int counter the purpose of UInt8?


By : Cindy Agravante
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further You are talking a few bytes per variable when storing as UInt8 instead of Int. These data types were conceived very early on in the history of computing, when memory was measured in the low KBs. Even the Apple Watch has 512MB.
Here's what Apple says in the Swift Book:

Convert [UInt32] -> [UInt8] -> [[UInt8]] in Swift


By : hahaxixi
Date : March 29 2020, 07:55 AM
like below fixes the issue If you profile (Cmd + I) your code, you will see that most of the time is on various "copy to buffer" functions. This happens when you append a new element to the array but it has run out of its initial allocated space so it must be moved to a location on the heap with more memory. Morals of the lesson: heap allocation is slow but unavoidable with arrays. Do it as few times as possible.
Try this:
code :
func convertWordToBytes2(fullW: [UInt32]) -> [[UInt8]] {
    let subSize = 6

    // We allocate the array only once per run since allocation is so slow
    // There will only be assignment to it after
    var combined48 = [UInt8](count: fullW.count * 4, repeatedValue: 0).splitBy(subSize)

    var row = 0
    var col = 0

    for i in 0...16 {
        for j in 24.stride(through: 0, by: -8) {
            let value = UInt8(truncatingBitPattern: fullW[i] >> UInt32(j))
            combined48[row][col] = value

            col += 1
            if col >= subSize {
                row += 1
                col = 0
            }
        }
    }

    return combined48
}
let testCases = (0..<1_000_000).map { _ in
    (0..<17).map { _ in arc4random() }
}

testCases.forEach {
    convertWordToBytes($0)
    convertWordToBytes2($0)
}
Weight          Self Weight         Symbol Name
9.35 s   53.2%  412.00 ms           specialized convertWordToBytes([UInt32]) -> [[UInt8]]
3.28 s   18.6%  344.00 ms           specialized convertWordToBytes2([UInt32]) -> [[UInt8]]
dispatch_apply(testCases.count, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) { i in
    convertWordToBytes2(testCases[i])
}
Weight    Self Weight       Symbol Name
2.28 s    6.4%  0 s         _dispatch_worker_thread3  0x58467
2.24 s    6.3%  0 s         _dispatch_worker_thread3  0x58463
2.22 s    6.2%  0 s         _dispatch_worker_thread3  0x58464
2.21 s    6.2%  0 s         _dispatch_worker_thread3  0x58466
2.21 s    6.2%  0 s         _dispatch_worker_thread3  0x58465
2.21 s    6.2%  0 s         _dispatch_worker_thread3  0x58461
2.18 s    6.1%  0 s         _dispatch_worker_thread3  0x58462

Convert parts of [UInt8] into UInt8


By : user2466315
Date : March 29 2020, 07:55 AM
wish helps you I am writing an app for my bachelor-project in electrical engineering and I am working with a byte array which represents a hexadecimal string. The received byte array looks like this: , Given an array :
code :
let bytes: [UInt8] = [204, 74, 3, 0, 97, 168, 209, 239]
let length = Int(bytes[2])
var msg = 0
var index = bytes.count - 3
var power = 1
while index > 2 {
    msg += Int(bytes[index]) * power
    power = power << 8
    index -= 1
}
print(msg)  //25000
var msg: UInt64 = 0
var index = 3
while index < bytes.count - 2 {
    msg <<= 8 //msg = msg << 8
    msg += UInt64(bytes[index])
    index += 1
}

Keras Model Output is float32 instead of uint8... despite data labels being uint8


By : Luger
Date : March 29 2020, 07:55 AM
may help you . Sigmoid returns a real number
The last layer happens to be the sigmoid activation function. It returns a real number from 0 and 1, not an integer.
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