The Gen_IsMMXMachine() utility function

The function tests the processor in the database server computer to determine if it has MMX technology support. If MMX technology support is found, Gen_IsMMXMachine() returns 1.

If the database server machine does not have MMX technology support, or if the FORCE_NO_MMX environment variable is set in the database server environment, Gen_IsMMXMachine() returns 0. On UNIX machines, Gen_IsMMXMachine() always returns 0.

To execute MMX instructions when possible and to execute portable C code on computers that do not have MMX technology support, call Gen_IsMMXMachine() in an IF statement.

Gen_IsMMXMachine() declares a static INT flag, MMXType. It first looks for the FORCE_NO_MMX environment variable, which must be set in the environment before the database server is started.

If FORCE_NO_MMX is found, the function sets MMXType to 0 without testing the CPU. If FORCE_NO_MMX is not found, the function tests the processor and sets the MMXType variable to 1 if MMX technology support is found or 0 if not. After the value of MMXType is set, Gen_IsMMXMachine() returns its value immediately, so that tests are performed once after the DataBlade module object file is loaded.