/* * File : finsh_heap.c * This file is part of RT-Thread RTOS * COPYRIGHT (C) 2006 - 2010, RT-Thread Development Team * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.rt-thread.org/license/LICENSE * * Change Logs: * Date Author Notes * 2010-03-22 Bernard first version */ #include #include "finsh_var.h" u_char finsh_heap[FINSH_HEAP_MAX]; struct finsh_block_header { u_long length; struct finsh_block_header* next; }; #define BLOCK_HEADER(x) (struct finsh_block_header*)(x) #define finsh_block_get_header(data) (struct finsh_block_header*)((u_char*)data - sizeof(struct finsh_block_header)) #define finsh_block_get_data(header) (u_char*)((struct finsh_block_header*)header + 1) #define HEAP_ALIGN_SIZE(size) (((size) + HEAP_ALIGNMENT - 1) & ~(HEAP_ALIGNMENT-1)) static struct finsh_block_header* free_list; static struct finsh_block_header* allocate_list; static void finsh_heap_gc(void); static void finsh_block_insert(struct finsh_block_header** list, struct finsh_block_header* header); static void finsh_block_remove(struct finsh_block_header** list, struct finsh_block_header* header); static void finsh_block_split(struct finsh_block_header* header, size_t size); static void finsh_block_merge(struct finsh_block_header** list, struct finsh_block_header* header); int finsh_heap_init(void) { /* clear heap to zero */ memset(&finsh_heap[0], 0, sizeof(finsh_heap)); /* init free and alloc list */ free_list = BLOCK_HEADER(&finsh_heap[0]); free_list->length = FINSH_HEAP_MAX - sizeof(struct finsh_block_header); free_list->next = NULL; allocate_list = NULL; return 0; } /** * allocate a block from heap */ void* finsh_heap_allocate(size_t size) { struct finsh_block_header* header; size = HEAP_ALIGN_SIZE(size); /* find the first fit block */ for (header = free_list; ((header != NULL) && (header->length <= size + sizeof(struct finsh_block_header))); header = header->next) ; if (header == NULL) { finsh_heap_gc(); /* find the first fit block */ for (header = free_list; ((header != NULL) && (header->length < size + sizeof(struct finsh_block_header))); header = header->next) ; /* there is no memory */ if (header == NULL) return NULL; } /* split block */ finsh_block_split(header, size); /* remove from free list */ finsh_block_remove(&free_list, header); header->next = NULL; /* insert to allocate list */ finsh_block_insert(&allocate_list, header); memset(finsh_block_get_data(header), 0, size); return finsh_block_get_data(header); } /** * release the allocated block */ void finsh_heap_free(void*ptr) { struct finsh_block_header* header; /* get block header */ header = finsh_block_get_header(ptr); /* remove from allocate list */ finsh_block_remove(&allocate_list, header); /* insert to free list */ finsh_block_insert(&free_list, header); finsh_block_merge(&free_list, header); } /** * garbage collector */ static void finsh_heap_gc(void) { int i; struct finsh_block_header *header, *temp; temp = NULL; /* find the first fit block */ for (header = allocate_list; header != NULL; ) { for (i = 0; i < FINSH_VARIABLE_MAX; i ++) { if (global_variable[i].type != finsh_type_unknown) { if (global_variable[i].value.ptr == finsh_block_get_data(header)) break; } } temp = header; header = header->next; /* this block is an unused block, release it */ if (i == FINSH_VARIABLE_MAX) { finsh_heap_free(finsh_block_get_data(temp)); } } } /** * insert a block to list */ void finsh_block_insert(struct finsh_block_header** list, struct finsh_block_header* header) { struct finsh_block_header* node; if (*list == NULL) { *list = header; return; } /* find out insert point */ node = *list; if (node > header) { /* insert node in the header of list */ header->next = node; *list = header; return; } else { for (node = *list; node; node = node->next) { if (node->next > header) break; if (node->next == NULL) break; } } /* insert node */ if (node->next != NULL) header->next = node->next; node->next = header; } /** * remove block from list */ void finsh_block_remove(struct finsh_block_header** list, struct finsh_block_header* header) { struct finsh_block_header* node; node = *list; if (node == header) { /* remove list header */ *list = header->next; header->next = NULL; return; } for (node = *list; node != NULL; node = node->next) { if (node->next == header) { node->next = header->next; break; } } } /** * split block */ void finsh_block_split(struct finsh_block_header* header, size_t size) { struct finsh_block_header* next; /* * split header into two node: * header->next->... */ next = BLOCK_HEADER((u_char*)header + sizeof(struct finsh_block_header) + size); next->length = header->length - sizeof(struct finsh_block_header) - size; header->length = size; next->next = header->next; header->next = next; } void finsh_block_merge(struct finsh_block_header** list, struct finsh_block_header* header) { struct finsh_block_header* prev_node; struct finsh_block_header* next_node; next_node = header->next; if (*list == header) prev_node = NULL; else { /* find out the previous header */ for (prev_node = *list; prev_node; prev_node =prev_node->next) { if (prev_node->next == header) break; } } /* try merge node */ /* merge to previous node */ if (prev_node != NULL && ((u_char*)prev_node + prev_node->length + sizeof(struct finsh_block_header) == (u_char*)header)) { /* is it close to next node? */ if ((next_node != NULL) && ((u_char*)header + header->length + sizeof(struct finsh_block_header) == (u_char*)next_node)) { /* merge three node */ prev_node->length += header->length + next_node->length + 2 * sizeof(struct finsh_block_header); prev_node->next = next_node->next; } else { prev_node->length += header->length + sizeof(struct finsh_block_header); prev_node->next = header->next; } } else /* merge to last node */ if ( (next_node != NULL) && ((u_char*)header + header->length + sizeof(struct finsh_block_header) == (u_char*)next_node)) { header->length += next_node->length + sizeof(struct finsh_block_header); header->next = next_node->next; } }