AX_CREATE_TARGET_H [(HEADER-FILE [,PREFIX)]
Create the header-file and let it contain ’#defines’ for the target platform. This macro is used for libraries that have platform-specific quirks. Instead of inventing a target-specific target.h.in files, just let it create a header file from the definitions of AC_CANONICAL_SYSTEM and put only ifdef’s in the installed header-files.
if the HEADER-FILE is absent, [target.h] is used. if the PREFIX is absent, [TARGET] is used. the prefix can be the packagename. (y:a-z-:A-Z_:)
The defines look like...
#ifndef TARGET_CPU_M68K #define TARGET_CPU_M68K "m68k" #endif
#ifndef TARGET_OS_LINUX #define TARGET_OS_LINUX "linux-gnu" #endif
#ifndef TARGET_OS_TYPE /* the string itself */ #define TARGET_OS_TYPE "linux-gnu" #endif
Detail: in the case of hppa1.1, the three idents "hppa1_1" "hppa1" and "hppa" are derived, for an m68k it just two, "m68k" and "m".
The CREATE_TARGET_H__ variant is almost the same function, but everything is lowercased instead of uppercased, and there is a "__" in front of each prefix, so it looks like...
#ifndef __target_os_linux #define __target_os_linux "linux-gnulibc2" #endif
#ifndef __target_os__ /* the string itself */ #define __target_os__ "linux-gnulibc2" #endif
#ifndef __target_cpu_i586 #define __target_cpu_i586 "i586" #endif
#ifndef __target_arch_i386 #define __target_arch_i386 "i386" #endif
#ifndef __target_arch__ /* cpu family arch */ #define __target_arch__ "i386" #endif
Other differences: the default string-define is "__" instead of "_TYPE".
Personally, I prefer the second variant (which had been the first in the devprocess of this file but I assume people will often fallback to the primary variant presented herein).
NOTE: CREATE_TARGET_H does also fill HOST_OS-defines Functionality has been split over functions called CREATE_TARGET_H_UPPER, CREATE_TARGET_H_LOWER, CREATE_TARGET_HOST_UPPER, and CREATE_TARGET_HOST_LOWER.
CREATE_TARGET_H uses CREATE_TARGET_H_UPPER CREATE_TARGET_HOST_UPPER CREATE_TARGET_H_ uses CREATE_TARGET_H_LOWER CREATE_TARGET_HOST_LOWER
There is now a CREATE_PREFIX_TARGET_H in this file as a shorthand for PREFIX_CONFIG_H from a target.h file, however w/o the target.h ever created (the prefix is a bit different, since we add an extra -target- and -host-).
Download the latest version of ax_create_target_h.m4 or browse the macro’s revision history.
Copyright © 2008 Guido U. Draheim firstname.lastname@example.org
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