libbb: add and use infrastructure for fixed page size optimization

function                                             old     new   delta
procps_scan                                         1121    1118      -3
getpagesize                                            6       -      -6
rpm_main                                            1037    1027     -10
rpm2cpio_main                                        120     110     -10
ptok                                                  38      21     -17
time_main                                           1282    1261     -21
mkswap_main                                          317     278     -39
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 0/6 up/down: 0/-106)           Total: -106 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index a74b3119f..db5bf7a51 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -391,6 +391,24 @@ void *mmap_read(int fd, size_t size) FAST_FUNC;
 void *mmap_anon(size_t size) FAST_FUNC;
 void *xmmap_anon(size_t size) FAST_FUNC;
 
+#if defined(__x86_64__) || defined(i386)
+# define BB_ARCH_FIXED_PAGESIZE 4096
+#else /* if defined(ARCH) */
+/* add you favorite arch today! */
+#endif
+
+#if defined BB_ARCH_FIXED_PAGESIZE
+# define IF_VARIABLE_ARCH_PAGESIZE(...) /*nothing*/
+# define bb_getpagesize()     BB_ARCH_FIXED_PAGESIZE
+# define INIT_PAGESIZE(var)   ((void)0)
+# define cached_pagesize(var) BB_ARCH_FIXED_PAGESIZE
+#else
+# define IF_VARIABLE_ARCH_PAGESIZE(...) __VA_ARGS__
+# define bb_getpagesize()     getpagesize()
+# define INIT_PAGESIZE(var)   ((var) = getpagesize())
+# define cached_pagesize(var) (var)
+#endif
+
 
 //TODO: supply a pointer to char[11] buffer (avoid statics)?
 extern const char *bb_mode_string(mode_t mode) FAST_FUNC;