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/*
* ***** BEGIN GPL LICENSE BLOCK *****
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Contributor(s): Nicholas Bishop
*
* ***** END GPL LICENSE BLOCK *****
*
*/
/** \file blender/blenlib/intern/stack.c
* \ingroup bli
*/
#include <string.h>
#include <stdlib.h> /* abort() */
#include "BLI_utildefines.h"
#include "MEM_guardedalloc.h"
#include "BLI_stack.h" /* own include */
#include "BLI_strict_flags.h"
// #define USE_TOTELEM
#define CHUNK_EMPTY ((size_t)-1)
/* target chunks size: 64kb */
#define CHUNK_SIZE_DEFAULT (1 << 16)
/* ensure we get at least this many elems per chunk */
#define CHUNK_ELEM_MIN 32
/* Gets the last element in the stack */
#define CHUNK_LAST_ELEM(_stack) \
((void)0, (((char *)(_stack)->chunk_curr->data) + \
((_stack)->elem_size * (_stack)->chunk_index)))
#define IS_POW2(a) (((a) & ((a) - 1)) == 0)
struct StackChunk {
struct StackChunk *next;
char data[0];
};
struct BLI_Stack {
struct StackChunk *chunk_curr; /* currently active chunk */
struct StackChunk *chunk_free; /* free chunks */
size_t chunk_index; /* index into 'chunk_curr' */
size_t chunk_elem_max; /* number of elements per chunk */
size_t elem_size;
#ifdef USE_TOTELEM
size_t totelem;
#endif
};
/**
* \return number of elements per chunk, optimized for slop-space.
*/
static size_t stack_chunk_elem_max_calc(const size_t elem_size, size_t chunk_size)
{
/* get at least this number of elems per chunk */
const size_t elem_size_min = elem_size * CHUNK_ELEM_MIN;
BLI_assert((elem_size != 0) && (chunk_size != 0));
while (UNLIKELY(chunk_size <= elem_size_min)) {
chunk_size <<= 1;
}
/* account for slop-space */
chunk_size -= (sizeof(struct StackChunk) + MEM_SIZE_OVERHEAD);
return chunk_size / elem_size;
}
BLI_Stack *BLI_stack_new_ex(const size_t elem_size, const char *description,
const size_t chunk_size)
{
BLI_Stack *stack = MEM_callocN(sizeof(*stack), description);
stack->chunk_elem_max = stack_chunk_elem_max_calc(elem_size, chunk_size);
stack->elem_size = elem_size;
/* force init */
stack->chunk_index = stack->chunk_elem_max - 1;
/* ensure we have a correctly rounded size */
BLI_assert((IS_POW2(stack->elem_size) == 0) ||
(IS_POW2((stack->chunk_elem_max * stack->elem_size) +
(sizeof(struct StackChunk) + MEM_SIZE_OVERHEAD))));
return stack;
}
/**
* Create a new homogeneous stack with elements of 'elem_size' bytes.
*/
BLI_Stack *BLI_stack_new(const size_t elem_size, const char *description)
{
return BLI_stack_new_ex(elem_size, description, CHUNK_SIZE_DEFAULT);
}
static void stack_free_chunks(struct StackChunk *data)
{
while (data) {
struct StackChunk *data_next = data->next;
MEM_freeN(data);
data = data_next;
}
}
/**
* Free the stack's data and the stack itself
*/
void BLI_stack_free(BLI_Stack *stack)
{
stack_free_chunks(stack->chunk_curr);
stack_free_chunks(stack->chunk_free);
MEM_freeN(stack);
}
/**
* Copies the source value onto the stack (note that it copies
* elem_size bytes from 'src', the pointer itself is not stored)
*/
void BLI_stack_push(BLI_Stack *stack, const void *src)
{
stack->chunk_index++;
if (UNLIKELY(stack->chunk_index == stack->chunk_elem_max)) {
struct StackChunk *chunk;
if (stack->chunk_free) {
chunk = stack->chunk_free;
stack->chunk_free = chunk->next;
}
else {
chunk = MEM_mallocN(
sizeof(*chunk) + (stack->elem_size * stack->chunk_elem_max),
__func__);
}
chunk->next = stack->chunk_curr;
stack->chunk_curr = chunk;
stack->chunk_index = 0;
}
BLI_assert(stack->chunk_index < stack->chunk_elem_max);
#ifdef USE_TOTELEM
stack->totelem++;
#endif
/* Copy source to end of stack */
memcpy(CHUNK_LAST_ELEM(stack), src, stack->elem_size);
}
/**
* Retrieves and removes the top element from the stack.
* The value is copies to \a dst, which must be at least \a elem_size bytes.
*
* Does not reduce amount of allocated memory.
*/
void BLI_stack_pop(BLI_Stack *stack, void *dst)
{
BLI_assert(BLI_stack_is_empty(stack) == false);
if (!BLI_stack_is_empty(stack)) {
memcpy(dst, CHUNK_LAST_ELEM(stack), stack->elem_size);
#ifdef USE_TOTELEM
stack->totelem--;
#endif
if (--stack->chunk_index == CHUNK_EMPTY) {
struct StackChunk *chunk_free;
chunk_free = stack->chunk_curr;
stack->chunk_curr = stack->chunk_curr->next;
chunk_free->next = stack->chunk_free;
stack->chunk_free = chunk_free;
stack->chunk_index = stack->chunk_elem_max - 1;
}
}
}
/**
* Returns true if the stack is empty, false otherwise
*/
bool BLI_stack_is_empty(const BLI_Stack *stack)
{
return (stack->chunk_curr == NULL);
}
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