memory.c

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/*
*********************************************************************************************************
 *                                            MEMORY
*
 * File    : memory.c
* Version : none
* Author  : JiaHui
*********************************************************************************************************
*/
 
// clang-format off
 
/****************************************************************************/
 
#include "config.h"
#include "memory.h"
#include "core.h"
 
#define ALIGNMENT                       ((size_t)4U)
#define MEM_ALIGN(size)                 (size_t)(((size) + (ALIGNMENT - 1)) & ~(ALIGNMENT - 1))
#define MIN_SIZE_TO_SPLIT               ((size_t)8U)
#define SIZE_OF_BLOCK_HEADER            ((size_t)MEM_ALIGN(sizeof(mem_blk_header_t)))
 
static uint8_t mem_heap[OS_CFG_HEAP_SIZE] __attribute__((aligned(ALIGNMENT)));
static mem_blk_header_t mem_blk_start;
static mem_blk_header_t *mem_blk_end_ptr = NULL;
static uint32_t byte_available = 0;

static void memory_heap_init(void)
{
    uint32_t total_heap_size = OS_CFG_HEAP_SIZE;
    uint32_t heap_addr = (uint32_t)mem_heap;
 
    /* Initialize first block */
    mem_blk_end_ptr = (mem_blk_header_t *)(heap_addr);
    mem_blk_end_ptr->size = total_heap_size - SIZE_OF_BLOCK_HEADER;
    mem_blk_end_ptr->state = MEM_STATE_FREE;
    mem_blk_end_ptr->next_ptr = NULL;
 
    mem_blk_start.size = 0;
    mem_blk_start.state = MEM_STATE_BUSY;
    mem_blk_start.next_ptr = mem_blk_end_ptr;
 
    byte_available = total_heap_size - SIZE_OF_BLOCK_HEADER;
}

void *akos_memory_malloc(size_t size)
{
    uint8_t *p_return = NULL;
    mem_blk_header_t *p_block = &mem_blk_start;
 
    /* Must check the end pointer first */
    if (mem_blk_end_ptr == NULL)
    {
        memory_heap_init();
    }
 
    /* Then check the size */
    size = MEM_ALIGN(size);
    if ((size == 0) || (size > byte_available))
    {
        core_assert(0, "OS_ERR_MEM_INVALID_SIZE");
        return (void *)p_return;
    }
 
    p_block = p_block->next_ptr;
    while (p_block != mem_blk_end_ptr)
    {
        if ((p_block->size < size) || (p_block->state == MEM_STATE_BUSY))
        {
            p_block = p_block->next_ptr;
        }
        else
        {
            /* Exit loop */
            break;
        }
    }
 
 
    /* Ensure selected block is actually usable (FREE and large enough). */
    if ((p_block->state == MEM_STATE_BUSY) || (p_block->size < size))
    {
        core_assert(0, "OS_ERR_MEM_NO_BLOCK");
        return (void *)p_return;
    }
 
    if ((p_block->size - size) > (MIN_SIZE_TO_SPLIT + SIZE_OF_BLOCK_HEADER))
    {
        mem_blk_header_t *p_new_block = (mem_blk_header_t *)(((uint8_t *)p_block) + SIZE_OF_BLOCK_HEADER + size);
        p_return = (uint8_t *)p_block + SIZE_OF_BLOCK_HEADER;
        p_new_block->size = p_block->size - size - SIZE_OF_BLOCK_HEADER;
        p_new_block->state = MEM_STATE_FREE;
        p_new_block->next_ptr = p_block->next_ptr;
 
        if (p_new_block->next_ptr == NULL)
        {
            mem_blk_end_ptr = p_new_block;
        }
 
        p_block->size = size;
        p_block->state = MEM_STATE_BUSY;
        p_block->next_ptr = p_new_block;
        byte_available -= (size + SIZE_OF_BLOCK_HEADER);
    }
    else
    {
        p_return = ((uint8_t *)p_block + SIZE_OF_BLOCK_HEADER);
        p_block->state = MEM_STATE_BUSY;
        byte_available -= p_block->size;
    }
 
 
    return (void *)p_return;
}

void akos_memory_free(void *p_addr)
{
    if ((mem_blk_end_ptr == NULL))
    {
        core_assert(0, "OS_ERR_MEM_LIST_IS_EMPTY");
        return;
    }
 
    if (p_addr == NULL)
    {
        core_assert(0, "OS_ERR_MEM_INVALID_ADDRESS");
        return;
    }
 
    uint8_t is_above_heap_end =
        ((uint8_t *)p_addr >= ((uint8_t *)mem_blk_end_ptr + SIZE_OF_BLOCK_HEADER + mem_blk_end_ptr->size));
 
    uint8_t is_below_heap_start =
        ((uint8_t *)p_addr < ((uint8_t *)mem_blk_start.next_ptr + SIZE_OF_BLOCK_HEADER));
 
    if (is_above_heap_end || is_below_heap_start)
    {
        core_assert(0, "OS_ERR_MEM_INVALID_ADDRESS");
        return;
    }
 
    mem_blk_header_t *p_block = (mem_blk_header_t *)((uint8_t *)p_addr - SIZE_OF_BLOCK_HEADER);
    mem_blk_header_t *p_block_temp = &mem_blk_start;
    mem_blk_header_t *p_prev_block = p_block_temp;
 
    while ((p_block_temp != mem_blk_end_ptr) && (p_block_temp != p_block))
    {
        p_prev_block = p_block_temp;
        p_block_temp = p_block_temp->next_ptr;
    }
 
    if (p_block_temp != p_block)
    {
        core_assert(0, "OS_ERR_MEM_INVALID_ADDRESS");
        return;
    }
 
    if (p_block_temp->state == MEM_STATE_FREE)
    {
        core_assert(0, "OS_ERR_MEM_DOUBLE_FREE");
        return;
    }
 
    byte_available += p_block_temp->size;
    p_block_temp->state = MEM_STATE_FREE;
 
    /* Merge next block */
    if ((p_block_temp->next_ptr != NULL) && (p_block_temp->next_ptr->state == MEM_STATE_FREE))
    {
        byte_available += SIZE_OF_BLOCK_HEADER;
        p_block_temp->size += p_block_temp->next_ptr->size + SIZE_OF_BLOCK_HEADER;
        p_block_temp->next_ptr = p_block_temp->next_ptr->next_ptr;
        if (p_block_temp->next_ptr == NULL)
        {
            mem_blk_end_ptr = p_block_temp;
        }
    }
 
    /* Merge previous block */
    if ((p_prev_block->state == MEM_STATE_FREE) && (p_prev_block != &mem_blk_start))
    {
        if (mem_blk_end_ptr == p_block_temp)
        {
            mem_blk_end_ptr = p_prev_block;
        }
 
        byte_available += SIZE_OF_BLOCK_HEADER;
        p_prev_block->size += p_block_temp->size + SIZE_OF_BLOCK_HEADER;
        p_prev_block->next_ptr = p_block_temp->next_ptr;
    }
}