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| author | Aurelien Jarno <aurelien@aurel32.net> | 2013-12-21 01:15:21 +0100 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2014-06-18 18:10:47 +0200 |
| commit | 739b7a90754924a0f023e8bb865d247ad0a60311 (patch) | |
| tree | 7871c0a08bd717d08352984487a990c273761e09 | |
| parent | 2edaf21b939eb3b7f058fbc3cb7f7e14d6262486 (diff) | |
| download | qemu-739b7a90754924a0f023e8bb865d247ad0a60311.tar.gz | |
bitops: provide an inline implementation of find_first_bit
find_first_bit has started to be used heavily in TCG code. The current
implementation based on find_next_bit is not optimal and can't be
optimized be the compiler if the bit array has a fixed size, which is
the case most of the time.
This new implementation does not use find_next_bit and is yet small
enough to be inlined.
Cc: Corentin Chary <corentin.chary@gmail.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
| -rw-r--r-- | include/qemu/bitops.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h index 340b1e73bd..7e2d5c996e 100644 --- a/include/qemu/bitops.h +++ b/include/qemu/bitops.h @@ -157,7 +157,17 @@ unsigned long find_next_zero_bit(const unsigned long *addr, static inline unsigned long find_first_bit(const unsigned long *addr, unsigned long size) { - return find_next_bit(addr, size, 0); + unsigned long result, tmp; + + for (result = 0; result < size; result += BITS_PER_LONG) { + tmp = *addr++; + if (tmp) { + result += ctzl(tmp); + return result < size ? result : size; + } + } + /* Not found */ + return size; } /** |