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rpi-vk-driver/driver/PoolAllocator.c

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#include "PoolAllocator.h"
#include "CustomAssert.h"
#include <stdint.h>
PoolAllocator createPoolAllocator(char* b, unsigned bs, unsigned s)
{
assert(b); //only allocated memory
assert(bs >= sizeof(void*)); //we need to be able to store
assert(s%bs==0); //we want a size that is the exact multiple of block size
assert(s >= bs); //at least 1 element
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PoolAllocator pa =
{
.buf = b,
.nextFreeBlock = (uint32_t*)b,
.blockSize = bs,
.size = s
};
//initialize linked list of free pointers
uint32_t* ptr = pa.nextFreeBlock;
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unsigned last = s/bs - 1;
for(unsigned c = 0; c < last; ++c)
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{
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*ptr = (char*)ptr + bs;
ptr = (char*)ptr + bs;
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}
*ptr = 0; //last element
return pa;
}
void destroyPoolAllocator(PoolAllocator* pa)
{
//actual memory freeing is done by caller
pa->buf = 0;
pa->nextFreeBlock = 0;
pa->blockSize = 0;
pa->size = 0;
}
void* poolAllocate(PoolAllocator* pa)
{
assert(pa->buf);
if(!pa->nextFreeBlock)
{
return 0; //no free blocks
}
//next free block will be allocated
void* ret = pa->nextFreeBlock;
//set next free block to the one the current next points to
pa->nextFreeBlock = (uint32_t*)*pa->nextFreeBlock;
return ret;
}
void poolFree(PoolAllocator* pa, void* p)
{
assert(pa->buf);
assert(p);
//set block to be freed to point to the current next free block
*(uint32_t*)p = (uint32_t)pa->nextFreeBlock;
//set next free block to the freshly freed block
pa->nextFreeBlock = p;
}