/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2016 Olaf Wintermann. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 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 THE COPYRIGHT HOLDER OR 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.
*/
/**
* @file stack.h
*
* Default stack memory allocation implementation.
*
* @author Mike Becker
* @author Olaf Wintermann
*/
#ifndef UCX_STACK_H
#define UCX_STACK_H
#include "ucx.h"
#include "allocator.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* UCX stack structure.
*/
typedef struct {
/** UcxAllocator based on this stack */
UcxAllocator allocator;
/** Stack size. */
size_t size;
/** Pointer to the bottom of the stack */
char *space;
/** Pointer to the top of the stack */
char *top;
} UcxStack;
/**
* Metadata for each UCX stack element.
*/
struct ucx_stack_metadata {
/**
* Location of the previous element (<code>NULL</code> if this is the first)
*/
char *prev;
/** Size of this element */
size_t size;
};
/**
* Initializes UcxStack structure with memory.
*
* @param stack a pointer to an uninitialized stack structure
* @param space the memory area that shall be managed
* @param size size of the memory area
* @return a new UcxStack structure
*/
void ucx_stack_init(UcxStack *stack, char* space, size_t size);
/**
* Allocates stack memory.
*
* @param stack a pointer to the stack
* @param n amount of memory to allocate
* @return a pointer to the allocated memory
* @see ucx_allocator_malloc()
*/
void *ucx_stack_malloc(UcxStack *stack, size_t n);
/**
* Alias for #ucx_stack_malloc().
* @param stack a pointer to the stack
* @param n amount of memory to allocate
* @return a pointer to the allocated memory
* @see ucx_stack_malloc
*/
#define ucx_stack_push(stack, n) ucx_stack_malloc(stack, n)
/**
* Allocates an array of stack memory
*
* The content of the allocated memory is set to zero.
*
* @param stack a pointer to the stack
* @param nelem amount of elements to allocate
* @param elsize amount of memory per element
* @return a pointer to the allocated memory
* @see ucx_allocator_calloc()
*/
void *ucx_stack_calloc(UcxStack *stack, size_t nelem, size_t elsize);
/**
* Alias for #ucx_stack_calloc().
*
* @param stack a pointer to the stack
* @param n amount of elements to allocate
* @param elsize amount of memory per element
* @return a pointer to the allocated memory
* @see ucx_stack_calloc
*/
#define ucx_stack_pusharr(stack,n,elsize) ucx_stack_calloc(stack,n,elssize)
/**
* Reallocates memory on the stack.
*
* Shrinking memory is always safe. Extending memory can be very expensive.
*
* @param stack the stack
* @param ptr a pointer to the memory that shall be reallocated
* @param n the new size of the memory
* @return a pointer to the new location of the memory
* @see ucx_allocator_realloc()
*/
void *ucx_stack_realloc(UcxStack *stack, void *ptr, size_t n);
/**
* Frees memory on the stack.
*
* Freeing stack memory behaves in a special way.
*
* If the element, that should be freed, is the top most element of the stack,
* it is removed from the stack. Otherwise it is marked as freed. Marked
* elements are removed, when they become the top most elements of the stack.
*
* @param stack a pointer to the stack
* @param ptr a pointer to the memory that shall be freed
*/
void ucx_stack_free(UcxStack *stack, void *ptr);
/**
* Returns the size of the top most element.
* @param stack a pointer to the stack
* @return the size of the top most element
*/
#define ucx_stack_topsize(stack) ((stack)->top ? ((struct ucx_stack_metadata*)\
(stack)->top - 1)->size : 0)
/**
* Removes the top most element from the stack and copies the content to <code>
* dest</code>, if specified.
*
* Use #ucx_stack_topsize()# to get the amount of memory that must be available
* at the location of <code>dest</code>.
*
* @param stack a pointer to the stack
* @param dest the location where the contents shall be written to, or <code>
* NULL</code>, if the element shall only be removed.
* @see ucx_stack_free
* @see ucx_stack_popn
*/
#define ucx_stack_pop(stack, dest) ucx_stack_popn(stack, dest, (size_t)-1)
/**
* Removes the top most element from the stack and copies the content to <code>
* dest</code>.
*
* In contrast to #ucx_stack_pop() the <code>dest</code> pointer <code>MUST
* NOT</code> be <code>NULL</code>.
*
* @param stack a pointer to the stack
* @param dest the location where the contents shall be written to
* @param n copies at most n elements to <code>dest</code>
* @see ucx_stack_pop
*/
void ucx_stack_popn(UcxStack *stack, void *dest, size_t n);
/**
* Returns the remaining available memory on the specified stack.
*
* @param stack a pointer to the stack
* @return the remaining available memory
*/
size_t ucx_stack_avail(UcxStack *stack);
/**
* Checks, if the stack is empty.
*
* @param stack a pointer to the stack
* @return nonzero, if the stack is empty, zero otherwise
*/
#define ucx_stack_empty(stack) (!(stack)->top)
/**
* Computes a recommended size for the stack memory area. Note, that
* reallocations have not been taken into account, so you might need to reserve
* twice as much memory to allow many reallocations.
*
* @param size the approximate payload
* @param elems the approximate count of element allocations
* @return a recommended size for the stack space based on the information
* provided
*/
#define ucx_stack_dim(size, elems) (size+sizeof(struct ucx_stack_metadata) * \
(elems + 1))
#ifdef __cplusplus
}
#endif
#endif /* UCX_STACK_H */