error: implicit declaration of function 'ACPI_PTR'

The error message "implicit declaration of function 'ACPI_PTR'" indicates that you are trying to use a function called 'ACPI_PTR' without declaring it or including the necessary header file.

To resolve this issue, you need to include the appropriate header file that declares the 'ACPI_PTR' function. The header file may vary depending on the context and the specific library or API you are using.

First, check the documentation or reference material for the library or API you are using to find out which header file you need to include. Once you have identified the correct header file, make sure to include it at the top of your source file before using the 'ACPI_PTR' function. For example:

#include <acpi.h> // or the appropriate header file

// Rest of your code
// Use the 'ACPI_PTR' function here

By including the correct header file, you should be able to resolve the "implicit declaration" error and properly use the 'ACPI_PTR' function.