heap.c

⑴ 提供简单命令 A、通过串口加载程序到指定内存 B、将程序烧写到 NANDFLASH 指定位置 C、LCD 操作函数 I、画点 II、画线 III、画圆 IV、显示图像

#include "struct.h"
#define HEAP_START 0x30000000
#define HEAP_END 0x33000000
#define UNUSED 0
#define USED 1
#define HEAP_NOTFIND 0
#define HEAP_FOUND  1
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;



//初始化堆
void init_heap()
{heap_head=(heap *)HEAP_START;
heap_head->size=(HEAP_START-HEAP_END+1)-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;
}

//分配内存函数
void * xmalloc(unsigned int size)
{heap *newblock;
heap *prtblock;
int stat=HEAP_NOTFIND;
size=(size+7)&~7;

heap_mark=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;
        break;      
        }
      }
  heap_crrunt=heap_crrunt->next;
  }
  if(stat==HEAP_NOTFIND)
  {return NULL;
  }
 prtblock=heap_crrunt;
 heap_crrunt=newblock;
 return (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;
  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;
       }
   }  
  if(nextblock!=NULL)
  {if(nextblock->used==UNUSED)
     {ptrblock->size=ptrblock->size+nextblock->size+sizeof(heap);
     ptrblock->end=nextblock->end;
     ptrblock->next=ptrblock->next;
     }
     }
   heap_crrunt=ptrblock;
   }