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remove duplicated implementations of log2

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This commit is contained in:
Sears Russell 2011-10-06 17:11:22 +00:00
parent d6763bc57b
commit 557c63a0f3
4 changed files with 13 additions and 96 deletions
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1
src/stasis/CMakeLists.txt
View file

@ -5,7 +5,6 @@ ADD_LIBRARY(stasis util/crc32.c
util/rw.c
util/doubleLinkedList.c
util/linkedlist.c
util/hash.c
util/log2.c
util/histogram.c
util/hashFunctions.c

91
src/stasis/util/hash.c
View file

@ -1,91 +0,0 @@
#include <stasis/util/hash.h>
#include <assert.h>
//#include <stdio.h>
/**
@todo Make hash.c 32/64bit little/big-endian clean...
@file Hash functions for stasis' in memory and persistent hash tables.
*/
#ifdef THOMAS_WANG_32
static inline int thomasWangs32BitMixFunction(int key)
{
key += ~(key << 15);
key ^= (key >> 10);
key += (key << 3);
key ^= (key >> 6);
key += ~(key << 11);
key ^= (key >> 16);
return key;
}
#else
#ifdef THOMAS_WANG_64
static inline unsigned long thomasWangs64BitMixFunction(unsigned long key)
{
key += ~(key << 32L);
key ^= (key >> 22L);
key += ~(key << 13L);
key ^= (key >> 8L);
key += (key << 3L);
key ^= (key >> 15L);
key += ~(key << 27L);
key ^= (key >> 31L);
return key;
}
#endif
#endif
static const char LogTable256[] =
{
0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
};
/*Taken from
http://graphics.stanford.edu/~seander/bithacks.html
@todo extend to handle unsigned long (this will mean 64bit on 64bit
platforms; need compiler macro to test for sizeof(long), test
harness to compare logBase2Slow's output with logBase2's output,
etc...)
*/
uint32_t logBase2(uint64_t v) {
uint32_t r = 0; // r will be lg(v)
uint32_t t, tt; // temporaries
if ((tt = v >> 16))
{
r = (t = v >> 24) ? 24 + LogTable256[t] : 16 + LogTable256[tt & 0xFF];
}
else
{
r = (t = v >> 8) ? 8 + LogTable256[t] : LogTable256[v];
}
return r;
}
uint32_t logBase2Slow(uint64_t v) {
uint32_t r = 0; // r will be lg(v)
while (v >>= 1) // unroll for more speed...
{
r++;
}
return r;
}

4
stasis/util/hash.h
View file

@ -1,5 +1,6 @@
#include <stasis/util/crc32.h>
#include <stasis/util/log2.h>
#include <stasis/common.h>
#ifndef __HASH_H
@ -13,7 +14,6 @@
static inline unsigned long stasis_util_two_to_the (char x) {
return (1 << ((long)x));
}
uint32_t logBase2(uint64_t value);
/**
This function maps from the length of the bucket list to a appropriate set
@ -21,7 +21,7 @@ uint32_t logBase2(uint64_t value);
*/
static inline void HASH_ENTRY(_get_size_params)(uint64_t desiredSize,
unsigned char * tableBits, uint64_t* nextExtension) {
*tableBits = logBase2(desiredSize)+1;
*tableBits = stasis_log_2_64(desiredSize)+1;
*nextExtension = ((desiredSize) - stasis_util_two_to_the(*tableBits-1));
}

13
stasis/util/log2.h
View file

@ -21,6 +21,15 @@
extern const uint8_t LogTable256[256];
/*Taken from
http://graphics.stanford.edu/~seander/bithacks.html
@todo extend to handle unsigned long (this will mean 64bit on 64bit
platforms; need compiler macro to test for sizeof(long), test
harness to compare logBase2Slow's output with logBase2's output,
etc...)
*/
/**
* @param v 32-bit word to find the log of
* @return lg_2(v)
@ -31,11 +40,11 @@ static inline uint8_t stasis_log_2_32(uint32_t v) {
if ((tt = v >> 16))
{
r = (t = tt >> 8) ? 24 + LogTable256[t] : 16 + LogTable256[tt];
r = ((t = tt >> 8)) ? 24 + LogTable256[t] : 16 + LogTable256[tt];
}
else
{
r = (t = v >> 8) ? 8 + LogTable256[t] : LogTable256[v];
r = ((t = v >> 8)) ? 8 + LogTable256[t] : LogTable256[v];
}
return r;
}