Programming Info D2XXPG31.pdf

FT-Win32 API Functions80overlapped I/O in which the application issues a request and receives control again only after therequest has been completed.The parameter, lpOverlapped, must point to an initialized OVERLAPPED structure.This function completes immediately, and the return code is zero, signifying an error. Anapplication should call FT_W32_GetLastError 81 to get the cause of the error. If the error code isERROR_IO_PENDING, the overlapped operation is still in progress, and the application canperform other processing. Eventually, the application checks the result of the overlapped requestby calling FT_W32_GetOverlappedResult 82 .If successful, the number of bytes written is returned in lpdwBytesWritten.ExampleThis example shows how to write 128 bytes to the device using non-overlapped I/O.FT_HANDLE ftHandle; // setup by FT_W32_CreateFile for overlapped i/ochar Buf[128]; // contains data to write to the deviceDWORD dwToWrite = 128;DWORD dwWritten;if (FT_W32_WriteFile(ftHandle, Buf, dwToWrite, &dwWritten, &osWrite)) {if (dwToWrite == dwWritten){// FT_W32_WriteFile OK}else{// FT_W32_WriteFile timeout}}else{// FT_W32_WriteFile failed}This example shows how to write 128 bytes to the device using overlapped I/O.FT_HANDLE ftHandle; // setup by FT_W32_CreateFile for overlapped i/ochar Buf[128]; // contains data to write to the deviceDWORD dwToWrite = 128;DWORD dwWritten;OVERLAPPED osWrite = { 0 };if (!FT_W32_WriteFile(ftHandle, Buf, dwToWrite, &dwWritten, &osWrite)) {if (FT_W32_GetLastError(ftHandle) == ERROR_IO_PENDING) {// write is delayed so do some other stuff until ...if (!FT_W32_GetOverlappedResult(ftHandle, &osWrite, &dwWritten, FALSE)){// error}else {if (dwToWrite == dwWritten){// FT_W32_WriteFile OK}else{// FT_W32_WriteFile timeout}}}}else {// FT_W32_WriteFIle OK}© Future Technology Devices International Ltd. 2005