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| author | Claudio Fontana <claudio.fontana@linaro.org> | 2013-12-17 19:42:35 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2013-12-17 20:12:51 +0000 |
| commit | afd3fe4ce56e6fb0d0384ddb8e3c4fac01935c37 (patch) | |
| tree | 1bdc85c034610f88fdc30746c121b6833b395f79 /include | |
| parent | 880777423525685ccaf1bf6967b27cc8a38e5f96 (diff) | |
| download | qemu-afd3fe4ce56e6fb0d0384ddb8e3c4fac01935c37.zip | |
host-utils: add clrsb32/64 - count leading redundant sign bits
this patch introduces wrappers for the clrsb builtins,
which count the leading redundant sign bits.
Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/qemu/host-utils.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h index 0f688c1c00..de85d282d0 100644 --- a/include/qemu/host-utils.h +++ b/include/qemu/host-utils.h @@ -228,6 +228,38 @@ static inline int cto64(uint64_t val) } /** + * clrsb32 - count leading redundant sign bits in a 32-bit value. + * @val: The value to search + * + * Returns the number of bits following the sign bit that are equal to it. + * No special cases; output range is [0-31]. + */ +static inline int clrsb32(uint32_t val) +{ +#if QEMU_GNUC_PREREQ(4, 7) + return __builtin_clrsb(val); +#else + return clz32(val ^ ((int32_t)val >> 1)) - 1; +#endif +} + +/** + * clrsb64 - count leading redundant sign bits in a 64-bit value. + * @val: The value to search + * + * Returns the number of bits following the sign bit that are equal to it. + * No special cases; output range is [0-63]. + */ +static inline int clrsb64(uint64_t val) +{ +#if QEMU_GNUC_PREREQ(4, 7) + return __builtin_clrsbll(val); +#else + return clz64(val ^ ((int64_t)val >> 1)) - 1; +#endif +} + +/** * ctpop8 - count the population of one bits in an 8-bit value. * @val: The value to search */ |