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1、对于动态内存分配管理，在安全关键的项目中切勿使用，因为内存碎片是无法避免的，而且不具有时间确定性。在安全关键的项目中要使用uCOS-II，III中数组方式的内存动态管理。RTX5也是支持这种方式的。
2、早前RTX4中的，我一直在使用，非常不错、像JPEG解码，MP3解码等里面用用，非常爽，就是不支持动态内存剩余返回，新版RTX5中的已经支持了。
3、这个文件可以独立用于裸机例子或者任何其它RTOS中。
- /*
- * Copyright (c) 2013-2018 Arm Limited. All rights reserved.
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Licensed under the Apache License, Version 2.0 (the License); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an AS IS BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * -----------------------------------------------------------------------------
- *
- * Project: CMSIS-RTOS RTX
- * Title: Memory functions
- *
- * -----------------------------------------------------------------------------
- */
- #include "rtx_lib.h"
- // Memory Pool Header structure
- typedef struct {
- uint32_t size; // Memory Pool size
- uint32_t used; // Used Memory
- } mem_head_t;
- // Memory Block Header structure
- typedef struct mem_block_s {
- struct mem_block_s *next; // Next Memory Block in list
- uint32_t info; // Block Info or max used Memory (in last block)
- } mem_block_t;
- // Memory Block Info: Length = <31:2>:'00', Type = <1:0>
- #define MB_INFO_LEN_MASK 0xFFFFFFFCU // Length mask
- #define MB_INFO_TYPE_MASK 0x00000003U // Type mask
- // Memory Head Pointer
- __STATIC_INLINE mem_head_t *MemHeadPtr (void *mem) {
- //lint -e{9079} -e{9087} "conversion from pointer to void to pointer to other type" [MISRA Note 6]
- return ((mem_head_t *)mem);
- }
- // Memory Block Pointer
- __STATIC_INLINE mem_block_t *MemBlockPtr (void *mem, uint32_t offset) {
- uint32_t addr;
- mem_block_t *ptr;
- //lint --e{923} --e{9078} "cast between pointer and unsigned int" [MISRA Note 8]
- addr = (uint32_t)mem + offset;
- ptr = (mem_block_t *)addr;
- return ptr;
- }
- // ==== Library functions ====
- /// Initialize Memory Pool with variable block size.
- /// \param[in] mem pointer to memory pool.
- /// \param[in] size size of a memory pool in bytes.
- /// \return 1 - success, 0 - failure.
- __WEAK uint32_t osRtxMemoryInit (void *mem, uint32_t size) {
- mem_head_t *head;
- mem_block_t *ptr;
- // Check parameters
- //lint -e{923} "cast from pointer to unsigned int" [MISRA Note 7]
- if ((mem == NULL) || (((uint32_t)mem & 7U) != 0U) || ((size & 7U) != 0U) ||
- (size < (sizeof(mem_head_t) + (2U*sizeof(mem_block_t))))) {
- EvrRtxMemoryInit(mem, size, 0U);
- //lint -e{904} "Return statement before end of function" [MISRA Note 1]
- return 0U;
- }
- // Initialize memory pool header
- head = MemHeadPtr(mem);
- head->size = size;
- head->used = sizeof(mem_head_t) + sizeof(mem_block_t);
- // Initialize first and last block header
- ptr = MemBlockPtr(mem, sizeof(mem_head_t));
- ptr->next = MemBlockPtr(mem, size - sizeof(mem_block_t));
- ptr->next->next = NULL;
- ptr->next->info = sizeof(mem_head_t) + sizeof(mem_block_t);
- ptr->info = 0U;
- EvrRtxMemoryInit(mem, size, 1U);
- return 1U;
- }
- /// Allocate a memory block from a Memory Pool.
- /// \param[in] mem pointer to memory pool.
- /// \param[in] size size of a memory block in bytes.
- /// \param[in] type memory block type: 0 - generic, 1 - control block
- /// \return allocated memory block or NULL in case of no memory is available.
- __WEAK void *osRtxMemoryAlloc (void *mem, uint32_t size, uint32_t type) {
- mem_block_t *ptr;
- mem_block_t *p, *p_new;
- uint32_t block_size;
- uint32_t hole_size;
- // Check parameters
- if ((mem == NULL) || (size == 0U) || ((type & ~MB_INFO_TYPE_MASK) != 0U)) {
- EvrRtxMemoryAlloc(mem, size, type, NULL);
- //lint -e{904} "Return statement before end of function" [MISRA Note 1]
- return NULL;
- }
- // Add block header to size
- block_size = size + sizeof(mem_block_t);
- // Make sure that block is 8-byte aligned
- block_size = (block_size + 7U) & ~((uint32_t)7U);
- // Search for hole big enough
- p = MemBlockPtr(mem, sizeof(mem_head_t));
- for (;;) {
- //lint -e{923} -e{9078} "cast from pointer to unsigned int"
- hole_size = (uint32_t)p->next - (uint32_t)p;
- hole_size -= p->info & MB_INFO_LEN_MASK;
- if (hole_size >= block_size) {
- // Hole found
- break;
- }
- p = p->next;
- if (p->next == NULL) {
- // Failed (end of list)
- EvrRtxMemoryAlloc(mem, size, type, NULL);
- //lint -e{904} "Return statement before end of function" [MISRA Note 1]
- return NULL;
- }
- }
- // Update used memory
- (MemHeadPtr(mem))->used += block_size;
- // Update max used memory
- p_new = MemBlockPtr(mem, (MemHeadPtr(mem))->size - sizeof(mem_block_t));
- if (p_new->info < (MemHeadPtr(mem))->used) {
- p_new->info = (MemHeadPtr(mem))->used;
- }
- // Allocate block
- if (p->info == 0U) {
- // No block allocated, set info of first element
- p->info = block_size | type;
- ptr = MemBlockPtr(p, sizeof(mem_block_t));
- } else {
- // Insert new element into the list
- p_new = MemBlockPtr(p, p->info & MB_INFO_LEN_MASK);
- p_new->next = p->next;
- p_new->info = block_size | type;
- p->next = p_new;
- ptr = MemBlockPtr(p_new, sizeof(mem_block_t));
- }
- EvrRtxMemoryAlloc(mem, size, type, ptr);
- return ptr;
- }
- /// Return an allocated memory block back to a Memory Pool.
- /// \param[in] mem pointer to memory pool.
- /// \param[in] block memory block to be returned to the memory pool.
- /// \return 1 - success, 0 - failure.
- __WEAK uint32_t osRtxMemoryFree (void *mem, void *block) {
- const mem_block_t *ptr;
- mem_block_t *p, *p_prev;
- // Check parameters
- if ((mem == NULL) || (block == NULL)) {
- EvrRtxMemoryFree(mem, block, 0U);
- //lint -e{904} "Return statement before end of function" [MISRA Note 1]
- return 0U;
- }
- // Memory block header
- ptr = MemBlockPtr(block, 0U);
- ptr--;
- // Search for block header
- p_prev = NULL;
- p = MemBlockPtr(mem, sizeof(mem_head_t));
- while (p != ptr) {
- p_prev = p;
- p = p->next;
- if (p == NULL) {
- // Not found
- EvrRtxMemoryFree(mem, block, 0U);
- //lint -e{904} "Return statement before end of function" [MISRA Note 1]
- return 0U;
- }
- }
- // Update used memory
- (MemHeadPtr(mem))->used -= p->info & MB_INFO_LEN_MASK;
- // Free block
- if (p_prev == NULL) {
- // Release first block, only set info to 0
- p->info = 0U;
- } else {
- // Discard block from chained list
- p_prev->next = p->next;
- }
- EvrRtxMemoryFree(mem, block, 1U);
- return 1U;
- }
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发表于 2018-3-12 01:58:30
楼主
发表于 2018-3-12 08:05:23
我比较喜欢这种模式！！！
