※ 引述《fmdjyl (小D(滴))》之铭言： : 请问用keilc，使用单晶片sm5964(使用51架构) : 请问能否使用malloc的函数呢(动态记忆体配置) : 因为想省记忆体空间。 : 还请高手指教~ 根据KEIL的说明： malloc Summary #include <stdlib.h> void xdata *malloc ( unsigned int size); /* block size to allocate */ Description The malloc function allocates a memory block from the memory pool of size bytes in length. Note Source code for this routine is provide in the LIB folder. You may modify the source to customize this function for your particular hardware environment. Return Value The malloc function returns a pointer to the allocated block or a null pointer if there is not enough memory to satisfy the allocation request. See Also calloc, free, init_mempool, realloc Example #include <stdlib.h> #include <stdio.h> /* for printf */ void tst_malloc (void) { unsigned char xdata *p; p = malloc (1000); /* allocate 1000 bytes */ if (p == NULL) printf ("Not enough memory space\n"); else printf ("Memory allocated\n"); } MALLOC.C /*----------------------------------------------------------------------------- MALLOC.C is part of the C51 Compiler package from Keil Software. Copyright (c) 1995-2002 Keil Software. All rights reserved. -----------------------------------------------------------------------------*/ #include <stdlib.h> /*----------------------------------------------- Memory pool block structure and typedefs. Memory is laid out as follows: {[NXT|LEN][BLK (LEN bytes)]}{[NXT|LEN][BLK]}... Note that the size of a node is: __mem__.len + sizeof (__mem__) -----------------------------------------------*/ struct __mem__ { struct __mem__ _MALLOC_MEM_ *next; /* single-linked list */ unsigned int len; /* length of following block */ }; typedef struct __mem__ __memt__; typedef __memt__ _MALLOC_MEM_ *__memp__; #define HLEN (sizeof(__memt__)) /*----------------------------------------------- Memory pool headers. AVAIL points to the first available block or is NULL if there are no free blocks. Note that the list is maintained in address order. AVAIL points to the block with the lowest address. That block points to the block with the next higher address and so on. -----------------------------------------------*/ extern __memt__ _MALLOC_MEM_ __mem_avail__ []; #define AVAIL (__mem_avail__[0]) #define MIN_BLOCK (HLEN * 4) /*----------------------------------------------------------------------------- void _MALLOC_MEM_ *malloc ( unsigned int size); number of bytes to allocate Return Value ------------ NULL FAILURE: No free blocks of size are available NON-NULL SUCCESS: Address of block returned -----------------------------------------------------------------------------*/ void _MALLOC_MEM_ *malloc ( unsigned int size) { __memp__ q; /* ptr to free block */ __memp__ p; /* q->next */ unsigned int k; /* space remaining in the allocated block */ /*----------------------------------------------- Initialization: Q is the pointer to the next available block. -----------------------------------------------*/ q = &AVAIL; /*----------------------------------------------- End-Of-List: P points to the next block. If that block DNE (P==NULL), we are at the end of the list. -----------------------------------------------*/ while (1) { if ((p = q->next) == NULL) { return (NULL); /* FAILURE */ } /*----------------------------------------------- Found Space: If block is large enough, reserve if. Otherwise, copy P to Q and try the next free block. -----------------------------------------------*/ if (p->len >= size) break; q = p; } /*----------------------------------------------- Reserve P: Use at least part of the P block to satisfy the allocation request. At this time, the following pointers are setup: P points to the block from which we allocate Q->next points to P -----------------------------------------------*/ k = p->len - size; /* calc. remaining bytes in block */ if (k < MIN_BLOCK) /* rem. bytes too small for new block */ { q->next = p->next; return (&p[1]); /* SUCCESS */ } /*----------------------------------------------- Split P Block: If P is larger than we need, we split P into two blocks: the leftover space and the allocated space. That means, we need to create a header in the allocated space. -----------------------------------------------*/ k -= HLEN; p->len = k; q = (__memp__ ) (((char _MALLOC_MEM_ *) (&p [1])) + k); q->len = size; return (&q[1]); /* SUCCESS */ } 所以说，当然可以。但是必需用在XRAM上，而且原始版本只支援线性分配、 并且一样会有一堆碎片、额外的配置表，如果你的CPU 有怪癖或奇怪构造（ 记忆体折页，分段.....） 你一样得自己解决。 而除非你要写网路驱动，或者USB BLOCK DEVICE。不然一般简单的应用自己 管理一下分配分配其效率比较好啦～ -- 作别人不愿作的事，是好人！。 作别人不敢作的事，是坏人！。 作别人不能作的事，是天才！。 作别人不会作的事，是…脑残！！ WolfLord --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 114.46.200.173