mirror of https://github.com/ocornut/imgui.git
Sepehr Taghdisian
10 years ago
3 changed files with 19 additions and 237 deletions
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/***********************************************************************************
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* Author: Sepehr Taghdisian (sep.tagh@gmail.com) |
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*/ |
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#ifndef IMMEM_H |
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#define IMMEM_H |
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// Note: This file is meant to included only inside imgui.cpp
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#ifndef IMGUI_INTERNAL_USE |
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#error "This file is intented for internal use only (as include)" |
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#endif |
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/* Linked-List ************************************************************************************/ |
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struct LinkedList |
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{ |
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LinkedList *next; |
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LinkedList *prev; |
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void *data; |
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LinkedList() : next(NULL), prev(NULL) {} |
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}; |
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static void list_add(struct LinkedList** plist, struct LinkedList* item, void* data) |
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{ |
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item->next = (*plist); |
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item->prev = NULL; |
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if (*plist != NULL) |
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(*plist)->prev = item; |
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*plist = item; |
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item->data = data; |
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} |
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static void list_addlast(struct LinkedList** plist, struct LinkedList* item, void* data) |
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{ |
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if (*plist != NULL) { |
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struct LinkedList* last = *plist; |
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while (last->next != NULL) last = last->next; |
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last->next = item; |
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item->prev = last; |
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item->next = NULL; |
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} else { |
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*plist = item; |
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item->prev = item->next = NULL; |
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} |
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item->data = data; |
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} |
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static void list_remove(struct LinkedList** plist, struct LinkedList* item) |
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{ |
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if (item->next != NULL) item->next->prev = item->prev; |
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if (item->prev != NULL) item->prev->next = item->next; |
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if (*plist == item) *plist = item->next; |
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item->next = item->prev = NULL; |
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} |
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/* PoolAlloc **************************************************************************************/ |
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template <typename T> |
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class PoolAlloc |
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{ |
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private: |
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LinkedList *m_blocks; /* first node of m_blocks */ |
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int m_block_cnt; |
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int m_items_max; /* maximum number of items allowed (per block) */ |
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ImGui_MallocCallback m_malloc; |
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ImGui_FreeCallback m_free; |
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private: |
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struct Block |
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{ |
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LinkedList node; /* linked-list node */ |
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unsigned char *buffer; /* memory buffer that holds all objects */ |
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void **ptrs; /* pointer references to the buffer */ |
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int iter; /* iterator for current buffer position */ |
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}; |
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private: |
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Block* create_block(int block_size) |
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{ |
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// Allocate in one call
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size_t total_sz = |
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sizeof(Block) + |
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sizeof(T)*block_size + |
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sizeof(void*)*block_size; |
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unsigned char *buff = (unsigned char*)m_malloc(total_sz); |
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if (buff == NULL) |
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return NULL; |
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memset(buff, 0x00, total_sz); |
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Block *block = (Block*)buff; |
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buff += sizeof(Block); |
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block->buffer = buff; |
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buff += sizeof(T)*block_size; |
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block->ptrs = (void**)buff; |
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// Assign pointer refs
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for (int i = 0; i < block_size; i++) |
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block->ptrs[block_size-i-1] = block->buffer + i*sizeof(T); |
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block->iter = block_size; |
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/* add to linked-list of the pool */ |
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list_addlast(&m_blocks, &block->node, block); |
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m_block_cnt++; |
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return block; |
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} |
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void destroy_block(Block *block) |
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{ |
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list_remove(&m_blocks, &block->node); |
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m_free(block); |
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m_block_cnt--; |
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} |
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public: |
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PoolAlloc() |
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{ |
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m_blocks = NULL; |
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m_block_cnt = 0; |
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m_items_max = 0; |
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m_malloc = NULL; |
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m_free = NULL; |
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} |
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bool create(int block_sz, ImGui_MallocCallback malloc_fn, ImGui_FreeCallback free_fn) |
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{ |
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m_items_max = block_sz; |
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m_malloc = malloc_fn; |
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m_free = free_fn; |
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// First block
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Block *block = create_block(block_sz); |
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if (block == NULL) { |
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destroy(); |
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return false; |
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} |
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return true; |
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} |
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void destroy() |
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{ |
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LinkedList* node = m_blocks; |
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while (node != NULL) { |
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LinkedList* next = node->next; |
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destroy_block((Block*)node->data); |
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node = next; |
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} |
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} |
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T* alloc() |
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{ |
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LinkedList* node = m_blocks; |
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while (node != NULL) { |
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Block *block = (Block*)node->data; |
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if (block->iter > 0) |
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return (T*)block->ptrs[--block->iter]; |
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node = node->next; |
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} |
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/* couldn't find a free block, create a new one */ |
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Block *block = create_block(m_items_max); |
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if (block == NULL) |
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return NULL; |
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return (T*)block->ptrs[--block->iter]; |
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} |
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void free(T *ptr) |
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{ |
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// find the block that pointer belongs to, and free the pointer from that block
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LinkedList *node = m_blocks; |
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int buffer_sz = m_items_max*sizeof(T); |
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unsigned char *u8ptr = (unsigned char*)ptr; |
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while (node != NULL) { |
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Block *block = (Block*)node->data; |
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if (u8ptr >= block->buffer && u8ptr < (block->buffer + buffer_sz)) { |
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IM_ASSERT(block->iter != m_items_max); |
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block->ptrs[block->iter++] = ptr; |
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return; |
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} |
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node = node->next; |
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} |
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// Memory block does not belong to the pool?!
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IM_ASSERT(0); |
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} |
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void clear() |
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{ |
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int block_size = m_items_max; |
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LinkedList* node = m_blocks; |
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while (node != NULL) { |
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Block *block = (Block*)node->data; |
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/* only re-assign pointer references to buffer */ |
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for (int i = 0; i < block_size; i++) |
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block->ptrs[block_size-i-1] = block->buffer + i*sizeof(T); |
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block->iter = block_size; |
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node = node->next; |
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} |
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} |
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}; |
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#endif // IMMEM_H
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