rt-memory动态内存分配改进

STM32

keil带的rt-memory动态内存分配源代码挺简练的，注释也很详尽。
但是每个内存块的控制部分需要8个字节，不大适合STM32/stm8这种小内存的片子，纯属浪费资源，现改成4字节。
请自行添加版权信息，测试。
修改前的代码：

/*----------------------------------------------------------------------------
* RL-ARM - RTX
*----------------------------------------------------------------------------
* Name: RT_MEMORY.H
* Purpose: Interface functions for Dynamic Memory Management System
* Rev.: V4.70
*----------------------------------------------------------------------------
*
* Copyright (c) 1999-2009 KEIL, 2009-2013 ARM Germany GmbH
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*---------------------------------------------------------------------------*/
#define U32 long
#define NULL 0
/* Types */
typedef struct mem { /* << Memory Pool management struct >> */
struct mem *next; /* Next Memory Block in the list */
U32 len; /* Length of data block */
} MEMP,*PMEMP;
/* Functions */
extern int rt_init_mem (void *pool, U32 size);
extern void *rt_alloc_mem (void *pool, U32 size);
extern int rt_free_mem (void *pool, void *mem);

复制代码

/*----------------------------------------------------------------------------
* RL-ARM - RTX
*----------------------------------------------------------------------------
* Name: RT_MEMORY.C
* Purpose: Interface functions for Dynamic Memory Management System
* Rev.: V4.70
*----------------------------------------------------------------------------
*
* Copyright (c) 1999-2009 KEIL, 2009-2013 ARM Germany GmbH
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*---------------------------------------------------------------------------*/
//#include "rt_TypeDef.h"
#include "rt_Memory.h"
/* Functions */
// Initialize Dynamic Memory pool
// Parameters:
// pool: Pointer to memory pool
// size: Size of memory pool in bytes
// Return: 0 - OK, 1 - Error
int rt_init_mem (void *pool, U32 size) {
MEMP *ptr;
if ((pool == NULL) || (size < sizeof(MEMP))) return (1);
ptr = (MEMP *)pool;
ptr->next = (MEMP *)((U32)pool + size - sizeof(MEMP *));
ptr->next->next = NULL;
ptr->len = 0;
return (0);
}
// Allocate Memory from Memory pool
// Parameters:
// pool: Pointer to memory pool
// size: Size of memory in bytes to allocate
// Return: Pointer to allocated memory
void *rt_alloc_mem (void *pool, U32 size) {
MEMP *p, *p_search, *p_new;
U32 hole_size;
if ((pool == NULL) || (size == 0)) return NULL;
/* Add header offset to 'size' */
size += sizeof(MEMP);
/* Make sure that block is 4-byte aligned */
size = (size + 3) & ~3;
p_search = (MEMP *)pool;
while (1) {
hole_size = (U32)p_search->next - (U32)p_search;
hole_size -= p_search->len;
/* Check if hole size is big enough */
if (hole_size >= size) break;
p_search = p_search->next;
if (p_search->next == NULL) {
/* Failed, we are at the end of the list */
return NULL;
}
}
if (p_search->len == 0) {
/* No block is allocated, set the Length of the first element */
p_search->len = size;
p = (MEMP *)(((U32)p_search) + sizeof(MEMP));
} else {
/* Insert new list element into the memory list */
p_new = (MEMP *)((U32)p_search + p_search->len);
p_new->next = p_search->next;
p_new->len = size;
p_search->next = p_new;
p = (MEMP *)(((U32)p_new) + sizeof(MEMP));
}
return (p);
}
// Free Memory and return it to Memory pool
// Parameters:
// pool: Pointer to memory pool
// mem: Pointer to memory to free
// Return: 0 - OK, 1 - Error
int rt_free_mem (void *pool, void *mem) {
MEMP *p_search, *p_prev, *p_return;
if ((pool == NULL) || (mem == NULL)) return (1);
p_return = (MEMP *)((U32)mem - sizeof(MEMP));
/* Set list header */
p_prev = NULL;
p_search = (MEMP *)pool;
while (p_search != p_return) {
p_prev = p_search;
p_search = p_search->next;
if (p_search == NULL) {
/* Valid Memory block not found */
return (1);
}
}
if (p_prev == NULL) {
/* First block to be released, only set length to 0 */
p_search->len = 0;
} else {
/* Discard block from chain list */
p_prev->next = p_search->next;
}
return (0);
}

复制代码

修改后的代码：

#define U32 long
#define U16 short
#define NULL 0
/* Types */
#pragma pack(1)
typedef struct mem { /* << Memory Pool management struct >> */
U16 next; /* Next Memory Block in the list */
U16 len; /* Length of data block */
} MEMP,*PMEMP;
#pragma pack()
/* Functions */
extern int rt_init_mem (void *pool, U16 size);
extern void *rt_alloc_mem (void *pool, U16 size);
extern int rt_free_mem (void *pool, void *mem);

复制代码

/* Functions */
// Initialize Dynamic Memory pool
// Parameters:
// pool: Pointer to memory pool
// size: Size of memory pool in bytes
// Return: 0 - OK, 1 - Error
int rt_init_mem (void *pool, U16 size) {
MEMP *ptr;
if ((pool == NULL) || (size < sizeof(MEMP))) return (1);
ptr = (MEMP *)pool;
ptr->next = size - 4;
((PMEMP)((U32)pool + (ptr->next)))->next = NULL;
ptr->len = 0;
return (0);
}
// Allocate Memory from Memory pool
// Parameters:
// pool: Pointer to memory pool
// size: Size of memory in bytes to allocate
// Return: Pointer to allocated memory
void *rt_alloc_mem (void *pool, U16 size) {
MEMP *p, *p_search, *p_new;
U32 hole_size;
if ((pool == NULL) || (size == 0)) return NULL;
/* Add header offset to 'size' */
size += sizeof(MEMP);
/* Make sure that block is 4-byte aligned */
size = (size + 3) & ~3;
p_search = (MEMP *)pool;
while (1) {
hole_size = (U32)p_search->next - ((U32)p_search - (U32)pool);
hole_size -= p_search->len;
/* Check if hole size is big enough */
if (hole_size >= size) break;
p_search = (MEMP *)((U32)pool + (p_search->next));
if (p_search->next == NULL) {
/* Failed, we are at the end of the list */
return NULL;
}
}
if (p_search->len == 0) {
/* No block is allocated, set the Length of the first element */
p_search->len = size;
p = (MEMP *)(((U32)p_search) + sizeof(MEMP));
} else {
/* Insert new list element into the memory list */
p_new = (MEMP *)((U32)p_search + p_search->len);
p_new->next = p_search->next;
p_new->len = size;
p_search->next = (U32)p_new - (U32)pool;
p = (MEMP *)(((U32)p_new) + sizeof(MEMP));
}
return (p);
}
// Free Memory and return it to Memory pool
// Parameters:
// pool: Pointer to memory pool
// mem: Pointer to memory to free
// Return: 0 - OK, 1 - Error
int rt_free_mem (void *pool, void *mem) {
MEMP *p_search, *p_prev, *p_return;
if ((pool == NULL) || (mem == NULL)) return (1);
p_return = (MEMP *)((U32)mem - sizeof(MEMP));
/* Set list header */
p_prev = NULL;
p_search = (MEMP *)pool;
while (p_search != p_return) {
p_prev = p_search;
if (p_search->next == NULL) {
/* Valid Memory block not found */
return (1);
}
p_search = (MEMP *)((U32)pool + (p_search->next));
}
if (p_prev == NULL) {
/* First block to be released, only set length to 0 */
p_search->len = 0;
} else {
/* Discard block from chain list */
p_prev->next = p_search->next;
}
return (0);
}

复制代码

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