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rpi-vk-driver/driver/map.c

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#include "map.h"
uint32_t getIndex(uint32_t key, uint32_t maxData)
{
//multiplicative hash
//with power of 2 W
uint32_t a = 0x678DDE6F;
return ((a * key) >> (32 - maxData)) % maxData;
}
void* getMapElement(map m, uint32_t key)
{
assert(m.maxData > 0);
assert(m.elements);
uint32_t index = getIndex(key, m.maxData);
//linear open addressing
while(m.elements[index].key != key && m.elements[index].data != 0){index = (index + 1) % m.maxData;}
return m.elements[index].data;
}
void setMapElement(map* m, uint32_t key, void* data)
{
assert(m);
assert(m->elements);
assert(m->maxData > 0);
uint32_t index = getIndex(key, m->maxData);
while(m->elements[index].key != key && m->elements[index].data != 0){index = (index + 1) % m->maxData;}
m->elements[index].data = data;
m->elements[index].key = key;
}
void deleteMapElement(map* m, uint32_t key)
{
assert(m);
assert(m->elements);
assert(m->maxData > 0);
uint32_t index = getIndex(key, m->maxData);
while(m->elements[index].key != key){++index;}
m->elements[index].data = 0;
}
map createMap(void* buf, uint32_t maxData)
{
map m =
{
.elements = buf,
.maxData = maxData
};
//lazy hashing
//0 means bucket is empty
for(uint32_t c = 0; c < m.maxData; ++c)
{
m.elements[c].data = 0;
}
return m;
}
void destroyMap(map* m)
{
//actual memory freeing is done by caller
m->elements = 0;
m->maxData = 0;
}