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This facility provides three entry points: ilog2() Log base 2 of unsigned long ilog2_u32() Log base 2 of u32 ilog2_u64() Log base 2 of u64 These facilities can either be used inside functions on dynamic data: int do_something(long q) { ...; y = ilog2(x) ...; } Or can be used to statically initialise global variables with constant values: unsigned n = ilog2(27); When performing static initialisation, the compiler will report "error: initializer element is not constant" if asked to take a log of zero or of something not reducible to a constant. They treat negative numbers as unsigned. When not dealing with a constant, they fall back to using fls() which permits them to use arch-specific log calculation instructions - such as BSR on x86/x86_64 or SCAN on FRV - if available. [akpm@osdl.org: MMC fix] Signed-off-by: David Howells <dhowells@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David Howells <dhowells@redhat.com> Cc: Wojtek Kaniewski <wojtekka@toxygen.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> |
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README |
linux-2.6 for H8/300 README Yoshinori Sato <ysato@users.sourceforge.jp> * Supported CPU H8/300H and H8S * Supported Target 1.simulator of GDB require patches. 2.AE 3068/AE 3069 more information MICROTRONIQUE <http://www.microtronique.com/> Akizuki Denshi Tsusho Ltd. <http://www.akizuki.ne.jp> (Japanese Only) 3.H8MAX see http://ip-sol.jp/h8max/ (Japanese Only) 4.EDOSK2674 see http://www.eu.renesas.com/products/mpumcu/tool/edk/support/edosk2674.html http://www.azpower.com/H8-uClinux/ * Toolchain Version gcc-3.1 or higher and patch see arch/h8300/tools_patch/README binutils-2.12 or higher gdb-5.2 or higher The environment that can compile a h8300-elf binary is necessary. * Userland Develop environment used h8300-elf toolchains. see http://www.uclinux.org/pub/uClinux/ports/h8/ * A few words of thanks Porting to H8/300 serieses is support of Information-technology Promotion Agency, Japan. I thank support. and All developer/user.