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- Overview
- How to proceed?
- Switching to 64-bit mode
- Mode for managing the compilation errors
- Compilation errors specific to the 64-bit mode
- Limits
- Various limits
- Registry and system files
Developing a 64-bit application
The recent computers (servers and desktop computers) are now equipped with "64-bit" operating systems. The main difference between a "32-bit" system and a "64-bit" system is as follows: in "64 bits", the applications and the system are no longer limited regarding the memory allocation. Indeed, in "32 bits", the operating system is limited to 4 GB while in "64 bits", there is nearly no limit (the limit is set to 18 billions GB). Operating mode of 32-bit applications: - The 32-bit WINDEV applications operate on a 64-bit operating system without modification: executable, setup, ...
- The 32-bit applications run on a 64-bit system are indicated in the task manager. These applications are neither disrupted nor run in a compatibility mode: they are subject to the memory constraints of the 32-bit applications. This limitation is not a constraint for most of the standard applications.
Switching to 64-bit mode For an application that requires a lot of memory, to prepare for the future or to specifically use 64-bit DLLs, you have the ability to easily transform a "32-bit" WINDEV application into a "64-bit" WINDEV application. To switch a WINDEV application from 32 bits to 64 bits:
- Open the 32-bit WINDEV project in the editor.
- Create a new project configuration: on the "Project" pane, in the "Project configuration" group, expand "New configuration" and select "Windows executable .. 64-bits".. The wizard for creating a project configuration starts.
- In the wizard:
- Specify the name of the project configuration. Choose an explicit name because this name will be used to create the generation directory of the files affected by the project configuration.
- Select the elements (windows, queries, ...) of this new configuration. In a standard case, all the elements of the 32-bit application must be selected.
- Validate the wizard.
- The project configuration is automatically created. If your development computer is in 64-bit mode, you have the ability to run the test of the 64-bit application via the 64-bit "GO" option.
Remark: Creating a 64-bit application only: You have the ability to define that an application is a "64-bit" application when creating the project. However, this solution is more complicated because a "64-bit" application does not operate on a "32-bit" system bur only on a "64-bit" system. Mode for managing the compilation errors - For the applications and services (Windows or Linux) in 32-bit mode, the 64-bit compilation errors are disabled.
- For the applications and services (Windows or Linux) in 64-bit mode, the 64-bit compilation errors are always enabled.
- For the components, libraries and Webservices, the 64-bit errors are always enabled.
Compilation errors specific to the 64-bit mode If the "32-bit" application was using Windows APIs or external DLLs, the transformation to "64-bit" mode may generate compilation errors. These compilation errors are specific to the "64-bit" mode. The most common error consists in using an "integer" variable to store a memory address.
Indeed, the memory addresses are stored on 8 bytes in 64-bit mode while they are stored on 4 bytes in 32-bit mode.
In this case, if a "standard" integer is used, the application may access a truncated memory address, therefore an invalid address. To avoid this problem, you must use the System Integer type of WLanguage: this type is uses an 8-byte integer in 64 bits and a 4-byte integer in 32 bits! Tips: - Don't forget to check that the APIs used exist in "64-bit" mode. And make sure that the DLL does not have a different name in "64-bit" mode and that its operating mode is identical.
If differences are noticed, you have the ability to use In64bitMode to call the API corresponding to the current system. - In 64 bits, if a too large value is assigned to a variable whose type is Integer on 1, 2, 4 or 8 bytes, the value of the variable will not be the same as in 32 bits.
Various limits - The wdxxxce.dll library for accessing a Mobile application does not operate in 64 bits.
- Hasp is not available in 64 bits.
- NetXXX functions: Only the client part is available in 64 bits, and it is compatible with a 32-bit server. The server part (NetStartServer and NetEndServer) is not available.
- 64-bit external languages: only C and C++ are available.
Registry and system files - Registry: On a 64-bit system, the 32-bit applications write into the registry from the following branch: "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node".
- Access to the system files: On a 64-bit system, the 32-bit applications use different system directories.
For example, an access to the "\Windows\system32\" directory will be performed in this folder from a 64-bit executable.
On the contrary, from a 32-bit executable, the access will be performed in the "\Windows\SysWOW64" folder.
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