mirror of
https://github.com/Yours3lf/rpi-vk-driver.git
synced 2024-12-05 17:24:14 +01:00
65 lines
1.4 KiB
C
65 lines
1.4 KiB
C
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#include "map.h"
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uint32_t getIndex(uint32_t key, uint32_t maxData)
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{
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//multiplicative hash
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//with power of 2 W
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uint32_t a = 0x678DDE6F;
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return ((a * key) >> (32 - maxData)) % maxData;
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}
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void* getMapElement(map m, uint32_t key)
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{
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assert(m.maxData > 0);
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assert(m.elements);
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uint32_t index = getIndex(key, m.maxData);
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//linear open addressing
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while(m.elements[index].key != key && m.elements[index].data != 0){index = (index + 1) % m.maxData;}
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return m.elements[index].data;
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}
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void setMapElement(map* m, uint32_t key, void* data)
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{
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assert(m);
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assert(m->elements);
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assert(m->maxData > 0);
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uint32_t index = getIndex(key, m->maxData);
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while(m->elements[index].key != key && m->elements[index].data != 0){index = (index + 1) % m->maxData;}
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m->elements[index].data = data;
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m->elements[index].key = key;
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}
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void deleteMapElement(map* m, uint32_t key)
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{
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assert(m);
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assert(m->elements);
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assert(m->maxData > 0);
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uint32_t index = getIndex(key, m->maxData);
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while(m->elements[index].key != key){++index;}
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m->elements[index].data = 0;
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}
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map createMap(void* buf, uint32_t maxData)
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{
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map m =
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{
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.elements = buf,
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.maxData = maxData
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};
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//lazy hashing
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//0 means bucket is empty
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for(uint32_t c = 0; c < m.maxData; ++c)
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{
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m.elements[c].data = 0;
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}
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return m;
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}
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void destroyMap(map* m)
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{
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//actual memory freeing is done by caller
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m->elements = 0;
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m->maxData = 0;
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}
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