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dix: add hashing functions to resource.h for others to use.

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The public hashing function HashResourceID uses the same hashing
hashing algorithm as resource.c uses internally, but it provides an
interface that will is usable by external modules. It provides a
parameter for the number of bits for the hash, instead of finding the
size from its internal hash table.

Signed-off-by: Erkki Seppälä <erkki.seppala@vincit.fi>
This commit is contained in:
Erkki Seppälä 2010-12-20 12:58:37 +02:00
parent 3ba0decb4b
commit a0b0fb83f9
2 changed files with 35 additions and 17 deletions
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39
dix/resource.c
View File

@ -636,25 +636,32 @@ InitClientResources(ClientPtr client)
return TRUE;
}
int
HashResourceID(XID id, int numBits)
{
id &= RESOURCE_ID_MASK;
switch (numBits)
{
case 6:
return ((int)(0x03F & (id ^ (id>>6) ^ (id>>12))));
case 7:
return ((int)(0x07F & (id ^ (id>>7) ^ (id>>13))));
case 8:
return ((int)(0x0FF & (id ^ (id>>8) ^ (id>>16))));
case 9:
return ((int)(0x1FF & (id ^ (id>>9))));
case 10:
return ((int)(0x3FF & (id ^ (id>>10))));
case 11:
return ((int)(0x7FF & (id ^ (id>>11))));
}
return -1;
}
static int
Hash(int client, XID id)
{
id &= RESOURCE_ID_MASK;
switch (clientTable[client].hashsize) {
case 6:
return ((int) (0x03F & (id ^ (id >> 6) ^ (id >> 12))));
case 7:
return ((int) (0x07F & (id ^ (id >> 7) ^ (id >> 13))));
case 8:
return ((int) (0x0FF & (id ^ (id >> 8) ^ (id >> 16))));
case 9:
return ((int) (0x1FF & (id ^ (id >> 9))));
case 10:
return ((int) (0x3FF & (id ^ (id >> 10))));
case 11:
return ((int) (0x7FF & (id ^ (id >> 11))));
}
return -1;
return HashResourceID(id, clientTable[client].hashsize);
}
static XID

13
include/resource.h
View File

@ -272,4 +272,15 @@ extern _X_EXPORT unsigned int GetXIDList(ClientPtr /*client */ ,
extern _X_EXPORT RESTYPE lastResourceType;
extern _X_EXPORT RESTYPE TypeMask;
#endif /* RESOURCE_H */
/** @brief A hashing function to be used for hashing resource IDs
@param id The resource ID to hash
@param numBits The number of bits in the resulting hash
@note This function can only handle INITHASHSIZE..MAXHASHSIZE bit
hashes and will return -1 if numBits is not within those bounds.
*/
extern _X_EXPORT int HashResourceID(XID id,
int numBits);
#endif /* RESOURCE_H */