66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
/**
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* Dynamic allocator that uses a fixed-length buffer that is hopefully big enough
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*
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* The two functions alloc & dealloc use the buffer as a simple stack.
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* Especially useful when an unpredictable amount of data will be received and have to be stored
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* during the transaction but discarded right after.
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*/
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#ifdef HAVE_DYN_MEM_ALLOC
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#include <stdint.h>
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#include "mem.h"
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#define SIZE_MEM_BUFFER 8192
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static uint8_t mem_buffer[SIZE_MEM_BUFFER];
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static size_t mem_idx;
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/**
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* Initializes the memory buffer index
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*/
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void mem_init(void) {
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mem_idx = 0;
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}
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/**
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* Resets the memory buffer index
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*/
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void mem_reset(void) {
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mem_init();
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}
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/**
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* Allocates (push) a chunk of the memory buffer of a given size.
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*
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* Checks to see if there are enough space left in the memory buffer, returns
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* the current location in the memory buffer and moves the index accordingly.
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*
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* @param[in] size Requested allocation size in bytes
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* @return Allocated memory pointer; \ref NULL if not enough space left.
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*/
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void *mem_alloc(size_t size) {
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if ((mem_idx + size) > SIZE_MEM_BUFFER) // Buffer exceeded
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{
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return NULL;
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}
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mem_idx += size;
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return &mem_buffer[mem_idx - size];
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}
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/**
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* De-allocates (pop) a chunk of memory buffer by a given size.
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*
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* @param[in] size Requested deallocation size in bytes
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*/
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void mem_dealloc(size_t size) {
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if (size > mem_idx) // More than is already allocated
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{
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mem_idx = 0;
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} else {
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mem_idx -= size;
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}
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}
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#endif // HAVE_DYN_MEM_ALLOC
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