diff options
author | unknown <serg@janus.mylan> | 2006-08-10 19:19:47 +0200 |
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committer | unknown <serg@janus.mylan> | 2006-08-10 19:19:47 +0200 |
commit | cd876fb11883f68f93027a70b5f3f99ad9234f27 (patch) | |
tree | 606c0ae70958f725f45d6d8f2bfbbf437a3873df /include/my_bit.h | |
parent | fe84903b15772782aa3bfbaa5fee60d480eaa4f2 (diff) | |
download | mariadb-git-cd876fb11883f68f93027a70b5f3f99ad9234f27.tar.gz |
amd64 atomic ops
lock-free alloc (WL#3229), lock-free hash (WL#3230)
bit functions made inline
include/Makefile.am:
lf.h added
mysys/Makefile.am:
lf_hash.c lf_dynarray.c lf_alloc-pin.c
include/atomic/nolock.h:
amd64 atomic ops
include/atomic/rwlock.h:
s/rw_lock/mutex/g
include/atomic/x86-gcc.h:
amd64 atomic ops
try PAUSE
include/my_global.h:
STATIC_INLINE
mysys/mf_keycache.c:
make bit functions inline
mysys/my_atomic.c:
STATIC_INLINE
mysys/my_bitmap.c:
make bit functions inline
sql/ha_myisam.cc:
make bit functions inline
sql/item_func.cc:
make bit functions inline
include/my_atomic.h:
STATIC_INLINE
mysys/my_bit.c:
make bit functions inline
sql/sql_select.cc:
make bit functions inline
storage/myisam/mi_create.c:
make bit functions inline
storage/myisam/mi_test2.c:
make bit functions inline
storage/myisam/myisamchk.c:
make bit functions inline
mysys/my_init.c:
thread_size moved to mysys
sql/mysql_priv.h:
thread_size moved to mysys
sql/set_var.cc:
thread_size moved to mysys
include/my_sys.h:
thread_size moved to mysys
sql/mysqld.cc:
thread_size moved to mysys
sql/sql_parse.cc:
thread_size moved to mysys
sql/sql_test.cc:
thread_size moved to mysys
include/lf.h:
dylf_dynarray refactored to remove 65536 elements limit
mysys/lf_alloc-pin.c:
dylf_dynarray refactored to remove 65536 elements limit
mysys/lf_dynarray.c:
dylf_dynarray refactored to remove 65536 elements limit
mysys/lf_hash.c:
dylf_dynarray refactored to remove 65536 elements limit
unittest/mysys/my_atomic-t.c:
fix to commit (remove debug code)
Diffstat (limited to 'include/my_bit.h')
-rw-r--r-- | include/my_bit.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/include/my_bit.h b/include/my_bit.h new file mode 100644 index 00000000000..71bbe2d4ba3 --- /dev/null +++ b/include/my_bit.h @@ -0,0 +1,107 @@ +/* + Some useful bit functions +*/ + +#ifdef HAVE_INLINE + +extern const char _my_bits_nbits[256]; +extern const uchar _my_bits_reverse_table[256]; + +/* + Find smallest X in 2^X >= value + This can be used to divide a number with value by doing a shift instead +*/ + +STATIC_INLINE uint my_bit_log2(ulong value) +{ + uint bit; + for (bit=0 ; value > 1 ; value>>=1, bit++) ; + return bit; +} + +STATIC_INLINE uint my_count_bits(ulonglong v) +{ +#if SIZEOF_LONG_LONG > 4 + /* The following code is a bit faster on 16 bit machines than if we would + only shift v */ + ulong v2=(ulong) (v >> 32); + return (uint) (uchar) (_my_bits_nbits[(uchar) v] + + _my_bits_nbits[(uchar) (v >> 8)] + + _my_bits_nbits[(uchar) (v >> 16)] + + _my_bits_nbits[(uchar) (v >> 24)] + + _my_bits_nbits[(uchar) (v2)] + + _my_bits_nbits[(uchar) (v2 >> 8)] + + _my_bits_nbits[(uchar) (v2 >> 16)] + + _my_bits_nbits[(uchar) (v2 >> 24)]); +#else + return (uint) (uchar) (_my_bits_nbits[(uchar) v] + + _my_bits_nbits[(uchar) (v >> 8)] + + _my_bits_nbits[(uchar) (v >> 16)] + + _my_bits_nbits[(uchar) (v >> 24)]); +#endif +} + +STATIC_INLINE uint my_count_bits_ushort(ushort v) +{ + return _my_bits_nbits[v]; +} + + +/* + Next highest power of two + + SYNOPSIS + my_round_up_to_next_power() + v Value to check + + RETURN + Next or equal power of 2 + Note: 0 will return 0 + + NOTES + Algorithm by Sean Anderson, according to: + http://graphics.stanford.edu/~seander/bithacks.html + (Orignal code public domain) + + Comments shows how this works with 01100000000000000000000000001011 +*/ + +STATIC_INLINE uint32 my_round_up_to_next_power(uint32 v) +{ + v--; /* 01100000000000000000000000001010 */ + v|= v >> 1; /* 01110000000000000000000000001111 */ + v|= v >> 2; /* 01111100000000000000000000001111 */ + v|= v >> 4; /* 01111111110000000000000000001111 */ + v|= v >> 8; /* 01111111111111111100000000001111 */ + v|= v >> 16; /* 01111111111111111111111111111111 */ + return v+1; /* 10000000000000000000000000000000 */ +} + +STATIC_INLINE uint32 my_clear_highest_bit(uint32 v) +{ + uint32 w=v >> 1; + w|= w >> 1; + w|= w >> 2; + w|= w >> 4; + w|= w >> 8; + w|= w >> 16; + return v & w; +} + +STATIC_INLINE uint32 my_reverse_bits(uint key) +{ + return + (_my_bits_reverse_table[ key & 255] << 24) | + (_my_bits_reverse_table[(key>> 8) & 255] << 16) | + (_my_bits_reverse_table[(key>>16) & 255] << 8) | + _my_bits_reverse_table[(key>>24) ]; +} + +#else +extern uint my_bit_log2(ulong value); +extern uint32 my_round_up_to_next_power(uint32 v); +uint32 my_clear_highest_bit(uint32 v); +uint32 my_reverse_bits(uint key); +extern uint my_count_bits(ulonglong v); +extern uint my_count_bits_ushort(ushort v); +#endif |