private static byte[] GetBytes(NfcProvHeader header)
{
int size = Marshal.SizeOf(header);
byte[] arr = new byte[size];
IntPtr ptr = Marshal.AllocHGlobal(size);
Marshal.StructureToPtr(header, ptr, true);
Marshal.Copy(ptr, arr, 0, size);
Marshal.FreeHGlobal(ptr);
return(arr);
}
/// <summary>
/// Function to format provisioning package into chunk data with a NfcProvHeader prefix.
/// </summary>
/// <param name="content">IBuffer to the provisioning package content.</param>
/// <param name="device">ProximityDevice instance passed in the messageHandler.</param>
/// <param name="messageHandler">Delegate handler to consume the chunk data.</param>
private static async Task ConvertToNfcMessageAsync(IBuffer content, ProximityDevice device, Func <ProximityDevice, IBuffer, CancellationToken, Task> messageHandlerAsync, CancellationToken ct)
{
var maxMessageSize = device.MaxMessageBytes;
var headerSize = GetNfcProvHeaderSize();
uint chunkSize = maxMessageSize - (uint)headerSize;
// Calculate the chunk count needed for this transfer.
uint chunks = content.Length / chunkSize;
if ((content.Length % chunkSize) > 0)
{
++chunks;
}
// Loop and compose the payload per chunk data.
for (uint posToRead = 0; posToRead < content.Length; posToRead += chunkSize)
{
var dataWriter = new DataWriter();
var header = new NfcProvHeader();
header.version = NFC_PROV_MESSAGE_CURRENT_VERSION; // Currently the supported version is 0x00.
header.leading = NFC_PROV_MESSAGE_LEADING_BYTE; // The leading byte should be always 0xFF.
header.index = (byte)(posToRead / chunkSize); // To specify which chunk to this message.
header.total = (byte)chunks; // To specify the total message count for this transfer.
int bufferSizeToAlloc = (int)maxMessageSize;
if (header.total == (header.index + 1))
{
bufferSizeToAlloc = headerSize + (int)(content.Length - posToRead);
}
// Write the prefix first and the chunk data of the provisioning package.
dataWriter.WriteBytes(GetBytes(header));
dataWriter.WriteBuffer(content, posToRead, (uint)(bufferSizeToAlloc - headerSize));
// Invoke the delegate handler to handle the NFC message.
await messageHandlerAsync(device, dataWriter.DetachBuffer(), ct);
}
}
private static int GetNfcProvHeaderSize()
{
var header = new NfcProvHeader();
return(Marshal.SizeOf(header));
}
private static int GetNfcProvHeaderSize()
{
var header = new NfcProvHeader();
return Marshal.SizeOf(header);
}
private static byte[] GetBytes(NfcProvHeader header)
{
int size = Marshal.SizeOf(header);
byte[] arr = new byte[size];
IntPtr ptr = Marshal.AllocHGlobal(size);
Marshal.StructureToPtr(header, ptr, true);
Marshal.Copy(ptr, arr, 0, size);
Marshal.FreeHGlobal(ptr);
return arr;
}
/// <summary>
/// Function to format provisioning package into chunk data with a NfcProvHeader prefix.
/// </summary>
/// <param name="content">IBuffer to the provisioning package content.</param>
/// <param name="device">ProximityDevice instance passed in the messageHandler.</param>
/// <param name="messageHandler">Delegate handler to consume the chunk data.</param>
private static async Task ConvertToNfcMessageAsync(IBuffer content, ProximityDevice device, Func<ProximityDevice, IBuffer, CancellationToken, Task> messageHandlerAsync, CancellationToken ct)
{
var maxMessageSize = device.MaxMessageBytes;
var headerSize = GetNfcProvHeaderSize();
uint chunkSize = maxMessageSize - (uint)headerSize;
// Calculate the chunk count needed for this transfer.
uint chunks = content.Length / chunkSize;
if ((content.Length % chunkSize) > 0)
{
++chunks;
}
// Loop and compose the payload per chunk data.
for (uint posToRead = 0; posToRead < content.Length; posToRead += chunkSize)
{
var dataWriter = new DataWriter();
var header = new NfcProvHeader();
header.version = NFC_PROV_MESSAGE_CURRENT_VERSION; // Currently the supported version is 0x00.
header.leading = NFC_PROV_MESSAGE_LEADING_BYTE; // The leading byte should be always 0xFF.
header.index = (byte)(posToRead / chunkSize); // To specify which chunk to this message.
header.total = (byte)chunks; // To specify the total message count for this transfer.
int bufferSizeToAlloc = (int)maxMessageSize;
if (header.total == (header.index + 1))
{
bufferSizeToAlloc = headerSize + (int)(content.Length - posToRead);
}
// Write the prefix first and the chunk data of the provisioning package.
dataWriter.WriteBytes(GetBytes(header));
dataWriter.WriteBuffer(content, posToRead, (uint)(bufferSizeToAlloc - headerSize));
// Invoke the delegate handler to handle the NFC message.
await messageHandlerAsync(device, dataWriter.DetachBuffer(), ct);
}
}