NAME
model — HP-UX machine identification
DESCRIPTION
There are certain inevitable distinctions between
HP-UX
implementations due to hardware differences.
Where such distinctions exist,
conditional compilation or other definitions
can be used to isolate the differences.
Flags and typedefs to resolve these distinctions are collected in the
<model.h>
header file which contains constants identifying various
HP-UX
implementations.
For example, header file
model.h
contains the following constants whose values are defined in
<sys/magic.h>:
#define HP_S_500 HP9000_ID
#define HP_S_200 HP98x6_ID
#define HP_S_300 CPU_HP_MC68020
#define HP_S_800 CPU_PA_RISC1_0
#define HP_S_700 CPU_PA_RISC1_1
Other such constants are added as appropriate when
HP-UX
extends to other machines in subsequent releases.
In addition,
model.h
has a statement defining the preprocessor constant
MYSYS
to represent the specific implementation for which compilation is desired.
MYSYS
is always equal to one of the constants above.
Conditional compilation can be used
to adapt a single file for execution on more than one
HP-UX
implementation if the file contains implementation-
or architecture-dependent features.
For example, the code segment:
#if MYSYS==HP_S_400
<statements>
#endif
causes statements following the if statement to be compiled
only
if the system processor is an HP 9000 Series 400 machine.
model.h
also contains typedefs for several predefined types
to enhance portability of certain types of code and files.
- int8, u_int8
Signed and unsigned 8-bit integers.
- int16, u_int16
Signed and unsigned 16-bit integers.
- int32, u_int32
Signed and unsigned 32-bit integers.
- machptr, u_machptr
Signed and unsigned integers large enough to hold a pointer.
Certain C preprocessor conditional compilation variables are defined
to aid in implementation-dependent code.
See
cpp(1).
