The Gen_IsMMXMachine() utility function
The Gen_IsMMXMachine() utility function can be used when you include Intel™ MMX media enhancement technology in your module.
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 module
object file is loaded.