2018-08-26 15:11:43 +02:00
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#include "ConsecutivePoolAllocator.h"
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#include "CustomAssert.h"
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#include <stdint.h>
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2020-03-01 16:26:12 +01:00
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#include <string.h>
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2018-08-26 15:11:43 +02:00
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ConsecutivePoolAllocator createConsecutivePoolAllocator(char* b, unsigned bs, unsigned s)
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{
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assert(b); //only allocated memory
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assert(bs >= sizeof(void*)); //we need to be able to store
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assert(s%bs==0); //we want a size that is the exact multiple of block size
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2019-08-19 23:12:51 +02:00
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assert(s >= bs); //at least 1 element
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2018-08-26 15:11:43 +02:00
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ConsecutivePoolAllocator pa =
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{
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.buf = b,
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.nextFreeBlock = (uint32_t*)b,
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.blockSize = bs,
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.size = s
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};
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//initialize linked list of free pointers
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uint32_t* ptr = pa.nextFreeBlock;
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unsigned last = s/bs - 1;
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for(unsigned c = 0; c < last; ++c)
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{
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2018-09-29 16:59:17 +02:00
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*ptr = (char*)ptr + bs;
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ptr = (char*)ptr + bs;
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2018-08-26 15:11:43 +02:00
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}
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*ptr = 0; //last element
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return pa;
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}
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void destroyConsecutivePoolAllocator(ConsecutivePoolAllocator* pa)
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{
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//actual memory freeing is done by caller
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pa->buf = 0;
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pa->nextFreeBlock = 0;
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pa->blockSize = 0;
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pa->size = 0;
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}
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//allocate numBlocks consecutive memory
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void* consecutivePoolAllocate(ConsecutivePoolAllocator* pa, uint32_t numBlocks)
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{
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assert(pa->buf);
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2020-03-02 22:50:08 +01:00
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// fprintf(stderr, "pa->nextFreeBlock %u\n", pa->nextFreeBlock);
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2018-08-26 15:11:43 +02:00
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if(!pa->nextFreeBlock)
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{
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return 0; //no free blocks
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}
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void* ret = 0;
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for(uint32_t* candidate = pa->nextFreeBlock; candidate; candidate = (uint32_t*)*candidate)
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{
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uint32_t found = 1;
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uint32_t* prevBlock = candidate;
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uint32_t* blockAfterCandidate = (uint32_t*)*candidate;
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//check if there are enough consecutive free blocks
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for(uint32_t c = 0; c < numBlocks - 1; ++c)
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{
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if(blockAfterCandidate - prevBlock != pa->blockSize)
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{
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//signal if not consecutive (ie. diff is greater than blocksize)
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found = 0;
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break;
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}
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prevBlock = blockAfterCandidate;
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blockAfterCandidate = (uint32_t*)*blockAfterCandidate;
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}
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//numblocks consecutive blocks found
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if(found)
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{
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ret = candidate;
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if(pa->nextFreeBlock == candidate)
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{
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//candidate found immediately
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pa->nextFreeBlock = blockAfterCandidate;
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}
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else
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{
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//somewhere the linked list would point to candidate, we need to correct this
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for(uint32_t* nextFreeBlockCandidate = pa->nextFreeBlock; nextFreeBlockCandidate; nextFreeBlockCandidate = (uint32_t*)*nextFreeBlockCandidate)
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{
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if((uint32_t*)*nextFreeBlockCandidate == candidate)
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{
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*nextFreeBlockCandidate = (uint32_t)blockAfterCandidate;
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break;
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}
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}
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}
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break;
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}
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}
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2020-03-01 16:26:12 +01:00
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//return a pointer pointing past the linked list ptr
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return ret > 0 ? (char*)ret + 4 : ret;
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2018-08-26 15:11:43 +02:00
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}
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//free numBlocks consecutive memory
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void consecutivePoolFree(ConsecutivePoolAllocator* pa, void* p, uint32_t numBlocks)
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{
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assert(pa->buf);
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assert(p);
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2020-03-01 16:26:12 +01:00
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p = (char*)p - 4;
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2018-08-26 15:11:43 +02:00
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if((void*)pa->nextFreeBlock > p)
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{
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for(uint32_t c = 0; c < numBlocks - 1; ++c)
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{
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//set each allocated block to form a linked list
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*(uint32_t*)((char*)p + c * pa->blockSize) = (uint32_t)((char*)p + (c + 1) * pa->blockSize);
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}
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//set last block to point to the next free
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*(uint32_t*)((char*)p + (numBlocks - 1) * pa->blockSize) = (uint32_t)pa->nextFreeBlock;
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//set next free to the newly freed block
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pa->nextFreeBlock = p;
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return;
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}
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//somewhere the linked list may point after the free block (or null), we need to correct this
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for(uint32_t* nextFreeBlockCandidate = pa->nextFreeBlock; nextFreeBlockCandidate; nextFreeBlockCandidate = (uint32_t*)*nextFreeBlockCandidate)
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{
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if((void*)*nextFreeBlockCandidate > p || !*nextFreeBlockCandidate)
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{
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for(uint32_t c = 0; c < numBlocks - 1; ++c)
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{
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//set each allocated block to form a linked list
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*(uint32_t*)((char*)p + c * pa->blockSize) = (uint32_t)((char*)p + (c + 1) * pa->blockSize);
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}
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//set last block to point to the next free
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*(uint32_t*)((char*)p + (numBlocks - 1) * pa->blockSize) = *nextFreeBlockCandidate;
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*nextFreeBlockCandidate = (uint32_t)p;
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break;
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}
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}
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}
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//if there's a block free after the current block, it just allocates one more block
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//else it frees current block and allocates a new one
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void* consecutivePoolReAllocate(ConsecutivePoolAllocator* pa, void* currentMem, uint32_t currNumBlocks)
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{
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2020-03-01 16:26:12 +01:00
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currentMem = (char*)currentMem - 4;
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2018-08-26 15:11:43 +02:00
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if(pa->nextFreeBlock == (uint32_t*)((char*)currentMem + currNumBlocks * pa->blockSize))
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{
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//we have one more block after current one, so just expand current
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pa->nextFreeBlock = (uint32_t*)*pa->nextFreeBlock;
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return currentMem;
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}
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else
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{
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void* ret = consecutivePoolAllocate(pa, currNumBlocks + 1);
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2020-03-01 16:26:12 +01:00
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char* newContents = ret;
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char* oldContents = currentMem;
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newContents += 4;
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oldContents += 4;
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memcpy(newContents, oldContents, currNumBlocks * pa->blockSize - 4);
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2018-08-26 15:11:43 +02:00
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consecutivePoolFree(pa, currentMem, currNumBlocks);
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2020-03-01 16:26:12 +01:00
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return newContents;
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2018-08-26 15:11:43 +02:00
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}
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}
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