裸机malloc实现

曾在arm裸机程序或者RTOS移植时，用到malloc，参考某位网友修改。

在6410跑过，所以设置6410的一块固定地址为堆，提供给malloc。

#define UNUSED 0#define USED 1#define HEAP_NOTFIND 0#define HEAP_FOUND  1static unsigned long HEAP_START = 0x54000000;static unsigned long HEAP_END = 0x58000000;typedef struct heap{int size;int start;int end;int used;struct heap *next;struct heap *prv;}heap;static heap *heap_head;static heap *heap_crrunt;static heap *heap_mark;static int heapnum=0;//初始化堆void init_heap(){heap_head = (heap *)HEAP_START;heap_head->size = (HEAP_END-HEAP_START)-sizeof(heap);heap_head->start = HEAP_START+sizeof(heap);heap_head->end = HEAP_END;heap_head->used = UNUSED;heap_head->next = NULL;heap_head->prv = NULL;heap_crrunt = heap_head;heapnum=0;printf("HEAP_START=%08x\n",HEAP_START);printf("HEAP_END=%08x\n",HEAP_END);printf("heap_head=0x%08x\n",heap_crrunt);printf("heap_head->start=%08x\n",heap_head->start);printf("heap_head->size=0x%08x\n",heap_head->size);}//分配内存函数void * xmalloc(unsigned int size){heap *newblock;heap *prtblock;int stat=HEAP_NOTFIND;int num = 0;size = (size+7)&~7;//printf("xmalloc:%d\n",heapnum);heap_mark=heap_crrunt;//printf("heap_crrunt:0x%08x\n",heap_crrunt);while(heap_crrunt->next != heap_mark) { if(heap_crrunt == NULL)  heap_crrunt = heap_head;    if(heap_crrunt->used == UNUSED)    {    if(heap_crrunt->size > size)       {       newblock = (heap*)((unsigned char *)heap_crrunt+(size+sizeof(heap)));        newblock->size = heap_crrunt->size-(size+sizeof(heap));        newblock->start = heap_crrunt->start+(size+sizeof(heap));        newblock->end = heap_crrunt->end;        newblock->used = UNUSED;        newblock->next = heap_crrunt->next;        newblock->prv = heap_crrunt;        heap_crrunt->used = USED;        heap_crrunt->size = size;        heap_crrunt->end = heap_crrunt->start+size;        heap_crrunt->next = newblock;        stat = HEAP_FOUND;heapnum++;        printf("heapnum:%d,heap:0x%08x,heapsize:%d\n",heapnum,heap_crrunt->start,size);        break;              }              }  num++;  delay(1);if(num > 1000){printf("alloc error\n");return NULL;}  heap_crrunt = heap_crrunt->next;    }    if(stat == HEAP_NOTFIND)  {  printf("malloc fail\n");  return NULL;  }   prtblock = heap_crrunt;   heap_crrunt = newblock;//printf("newblock=0x%08x\n",newblock);//printf("newblock start=0x%08x\n",newblock->start); return ((heap *)((u32)prtblock + sizeof(heap))); }   //释放void xfree(void *block){heap * ptrblock;heap * prvblock;heap * nextblock;    if(block==NULL)   return ;    ptrblock = (heap *)((unsigned char *)block-sizeof(heap));  ptrblock->used = UNUSED;  prvblock = ptrblock->prv;  nextblock = ptrblock->next;  printf("xfree\n");  if(prvblock != NULL)   {   if(prvblock->used==UNUSED)      {      prvblock->size = prvblock->size+ptrblock->size+sizeof(heap);       prvblock->end = ptrblock->end;       prvblock->next = ptrblock->next;       ptrblock = prvblock;heapnum--;       }   }    if(nextblock != NULL)  {  if(nextblock->used == UNUSED)     {     ptrblock->size = ptrblock->size+nextblock->size+sizeof(heap);     ptrblock->end = nextblock->end;     ptrblock->next = ptrblock->next;heapnum--;     }  }      heap_crrunt = ptrblock;}