diff options
author | David Howells <dhowells@redhat.com> | 2006-12-08 02:37:49 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 08:28:51 -0800 |
commit | f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8 (patch) | |
tree | 0aa5379150574374351fb92af7881a48dbfcf2ce /arch | |
parent | b3d7ae5f47a58a9f7b152deeaf7daa1fc558a8f1 (diff) | |
download | kernel_samsung_espresso10-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.zip kernel_samsung_espresso10-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.tar.gz kernel_samsung_espresso10-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.tar.bz2 |
[PATCH] LOG2: Implement a general integer log2 facility in the kernel
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>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/alpha/Kconfig | 8 | ||||
-rw-r--r-- | arch/arm/Kconfig | 8 | ||||
-rw-r--r-- | arch/arm26/Kconfig | 8 | ||||
-rw-r--r-- | arch/avr32/Kconfig | 8 | ||||
-rw-r--r-- | arch/cris/Kconfig | 8 | ||||
-rw-r--r-- | arch/frv/Kconfig | 8 | ||||
-rw-r--r-- | arch/h8300/Kconfig | 8 | ||||
-rw-r--r-- | arch/i386/Kconfig.cpu | 8 | ||||
-rw-r--r-- | arch/ia64/Kconfig | 8 | ||||
-rw-r--r-- | arch/m32r/Kconfig | 8 | ||||
-rw-r--r-- | arch/m68k/Kconfig | 8 | ||||
-rw-r--r-- | arch/m68knommu/Kconfig | 8 | ||||
-rw-r--r-- | arch/mips/Kconfig | 8 | ||||
-rw-r--r-- | arch/parisc/Kconfig | 8 | ||||
-rw-r--r-- | arch/powerpc/Kconfig | 8 | ||||
-rw-r--r-- | arch/ppc/Kconfig | 8 | ||||
-rw-r--r-- | arch/s390/Kconfig | 8 | ||||
-rw-r--r-- | arch/sh/Kconfig | 8 | ||||
-rw-r--r-- | arch/sh64/Kconfig | 8 | ||||
-rw-r--r-- | arch/sparc/Kconfig | 8 | ||||
-rw-r--r-- | arch/sparc64/Kconfig | 8 | ||||
-rw-r--r-- | arch/v850/Kconfig | 8 | ||||
-rw-r--r-- | arch/x86_64/Kconfig | 8 | ||||
-rw-r--r-- | arch/xtensa/Kconfig | 8 |
24 files changed, 192 insertions, 0 deletions
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 7e55ea6..84caf50 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8c05d43..aa1d400 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -74,6 +74,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/arm26/Kconfig b/arch/arm26/Kconfig index c14fe91..74eba8b 100644 --- a/arch/arm26/Kconfig +++ b/arch/arm26/Kconfig @@ -41,6 +41,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig index 5f1694e..bb059a4 100644 --- a/arch/avr32/Kconfig +++ b/arch/avr32/Kconfig @@ -45,6 +45,14 @@ config GENERIC_TIME config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_BUST_SPINLOCK bool diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig index 6a1238a..3474309 100644 --- a/arch/cris/Kconfig +++ b/arch/cris/Kconfig @@ -16,6 +16,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig index cf1c446..7561d7b 100644 --- a/arch/frv/Kconfig +++ b/arch/frv/Kconfig @@ -41,6 +41,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default y + +config ARCH_HAS_ILOG2_U64 + bool + default y + mainmenu "Fujitsu FR-V Kernel Configuration" source "init/Kconfig" diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index cabf0bf..34a84bc 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -29,6 +29,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/i386/Kconfig.cpu b/arch/i386/Kconfig.cpu index 821fd26..2aecfba 100644 --- a/arch/i386/Kconfig.cpu +++ b/arch/i386/Kconfig.cpu @@ -248,6 +248,14 @@ config RWSEM_XCHGADD_ALGORITHM depends on !M386 default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_CALIBRATE_DELAY bool default y diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 75d8397..fcacfe2 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -34,6 +34,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig index 41fd490..f383dab 100644 --- a/arch/m32r/Kconfig +++ b/arch/m32r/Kconfig @@ -214,6 +214,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 7bc1446..70a577c 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -17,6 +17,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig index aa70dde..25993c2 100644 --- a/arch/m68knommu/Kconfig +++ b/arch/m68knommu/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d8af858f..57af8d8 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -819,6 +819,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index d210123..0f9ff61 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -25,6 +25,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 291c95a..97c7a21 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -41,6 +41,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig index f76a146..692b5ba 100644 --- a/arch/ppc/Kconfig +++ b/arch/ppc/Kconfig @@ -19,6 +19,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default y + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 583d9ff..45e47bf 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -22,6 +22,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index d83d64a..8e24c40 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -59,6 +59,14 @@ config LOCKDEP_SUPPORT bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "System type" diff --git a/arch/sh64/Kconfig b/arch/sh64/Kconfig index 58c678e..7bc0744 100644 --- a/arch/sh64/Kconfig +++ b/arch/sh64/Kconfig @@ -39,6 +39,14 @@ config RWSEM_XCHGADD_ALGORITHM config GENERIC_ISA_DMA bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source init/Kconfig menu "System type" diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 92a7c8a..d0dec1e 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -166,6 +166,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config SUN_PM bool default y diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig index b627f8d..d391d11 100644 --- a/arch/sparc64/Kconfig +++ b/arch/sparc64/Kconfig @@ -34,6 +34,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config AUDIT_ARCH bool default y diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig index 37ec644..bcf8258 100644 --- a/arch/v850/Kconfig +++ b/arch/v850/Kconfig @@ -38,6 +38,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + # Turn off some random 386 crap that can affect device config config ISA bool diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index 3254a61..3ac581d 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -101,6 +101,14 @@ config GENERIC_BUG default y depends on BUG +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index c1e69a1..9eccfbd 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -34,6 +34,14 @@ config GENERIC_HARDIRQS bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "Processor type and features" |