If one type is shorter than the other, it must be extended when converting to the longer type. Inline 64-bit functions such as PtrToUlong and UlongToPtr safely convert between pointer and integer types without relying on assumptions about the relative sizes of these types. The preceding code example preserves all 64 bits of the pointer value. OEMCUIPPARAM->pDrvOptItems.UserData = (ULONG_PTR)pData // Correct The correct approach is to cast the pointer to ULONG_PTR, as shown in the following code example. The preceding code example casts the pData pointer to type ULONG, which can truncate the pointer value if sizeof( pData) > sizeof(ULONG). OEMCUIPPARAM->pDrvOptItems.UserData = (ULONG)pData // Wrong The following code example shows what not to do if you copy a 64-bit pointer value to this field. An unsigned integer of type DWORD_PTR or ULONG_PTR is always large enough to store the entire pointer, regardless of whether the code is compiled for a 32-bit or 64-bit computer.įor example, the pDrvOptItems.UserData pointer field in the OEMCUIPPARAM structure is of type ULONG_PTR. Instead, cast the pointer to type DWORD_PTR or ULONG_PTR. If you cast a pointer to type DWORD or ULONG, a 64-bit pointer might be truncated. For 64-bit code, this assumption is dangerous. If you have experience writing code for 32-bit machines, you might be used to assuming that a pointer value fits into a DWORD or ULONG.
In existing 32-bit driver code, be careful about conversions between pointer types and integer types such as DWORD or ULONG.
If a 32-bit application is running on a 64-bit version of the Microsoft Windows operating system, a printer driver plug-in that is running in the context of the Splwow64.exe thunking process should not call the GDI CreateDC function this call will fail. How to Use Decorations in INF Files for Printer Drivers This topic describes some of the limitations and problems that you might encounter in writing a 64-bit printer driver.įor more information about using decorations to identify 64-bit architecture, see the following topics: If you are writing a 64-bit driver or writing a driver that can be compiled to run on both 32-bit and 64-bit systems, follow the 64-bit porting guidelines in Porting Your Driver to 64-Bit Windows. We recommend that you use Microsoft's IPP inbox class driver, along with Print Support Apps (PSA), to customize the print experience in Windows 10 and 11 for printer device development.įor more information, see the Print support app design guide.
0 kommentar(er)
