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#ifndef SECP256K1_PREALLOCATED_H
#define SECP256K1_PREALLOCATED_H
#include "secp256k1.h"
#ifdef __cplusplus
extern "C" {
#endif
/* The module provided by this header file is intended for settings in which it
* is not possible or desirable to rely on dynamic memory allocation. It provides
* functions for creating, cloning, and destroying secp256k1 context objects in a
* contiguous fixed-size block of memory provided by the caller.
*
* Context objects created by functions in this module can be used like contexts
* objects created by functions in secp256k1.h, i.e., they can be passed to any
* API function that expects a context object (see secp256k1.h for details). The
* only exception is that context objects created by functions in this module
* must be destroyed using secp256k1_context_preallocated_destroy (in this
* module) instead of secp256k1_context_destroy (in secp256k1.h).
*
* It is guaranteed that functions in this module will not call malloc or its
* friends realloc, calloc, and free.
*/
/** Determine the memory size of a secp256k1 context object to be created in
* caller-provided memory.
*
* The purpose of this function is to determine how much memory must be provided
* to secp256k1_context_preallocated_create.
*
* Returns: the required size of the caller-provided memory block
* In: flags: which parts of the context to initialize.
*/
SECP256K1_API size_t secp256k1_context_preallocated_size(
unsigned int flags
) SECP256K1_WARN_UNUSED_RESULT;
/** Create a secp256k1 context object in caller-provided memory.
*
* The caller must provide a pointer to a rewritable contiguous block of memory
* of size at least secp256k1_context_preallocated_size(flags) bytes, suitably
* aligned to hold an object of any type.
*
* The block of memory is exclusively owned by the created context object during
* the lifetime of this context object, which begins with the call to this
* function and ends when a call to secp256k1_context_preallocated_destroy
* (which destroys the context object again) returns. During the lifetime of the
* context object, the caller is obligated not to access this block of memory,
* i.e., the caller may not read or write the memory, e.g., by copying the memory
* contents to a different location or trying to create a second context object
* in the memory. In simpler words, the prealloc pointer (or any pointer derived
* from it) should not be used during the lifetime of the context object.
*
* Returns: a newly created context object.
* In: prealloc: a pointer to a rewritable contiguous block of memory of
* size at least secp256k1_context_preallocated_size(flags)
* bytes, as detailed above (cannot be NULL)
* flags: which parts of the context to initialize.
*
* See also secp256k1_context_randomize (in secp256k1.h)
* and secp256k1_context_preallocated_destroy.
*/
SECP256K1_API secp256k1_context* secp256k1_context_preallocated_create(
void* prealloc,
unsigned int flags
) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
/** Determine the memory size of a secp256k1 context object to be copied into
* caller-provided memory.
*
* Returns: the required size of the caller-provided memory block.
* In: ctx: an existing context to copy (cannot be NULL)
*/
SECP256K1_API size_t secp256k1_context_preallocated_clone_size(
const secp256k1_context* ctx
) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
/** Copy a secp256k1 context object into caller-provided memory.
*
* The caller must provide a pointer to a rewritable contiguous block of memory
* of size at least secp256k1_context_preallocated_size(flags) bytes, suitably
* aligned to hold an object of any type.
*
* The block of memory is exclusively owned by the created context object during
* the lifetime of this context object, see the description of
* secp256k1_context_preallocated_create for details.
*
* Returns: a newly created context object.
* Args: ctx: an existing context to copy (cannot be NULL)
* In: prealloc: a pointer to a rewritable contiguous block of memory of
* size at least secp256k1_context_preallocated_size(flags)
* bytes, as detailed above (cannot be NULL)
*/
SECP256K1_API secp256k1_context* secp256k1_context_preallocated_clone(
const secp256k1_context* ctx,
void* prealloc
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_WARN_UNUSED_RESULT;
/** Destroy a secp256k1 context object that has been created in
* caller-provided memory.
*
* The context pointer may not be used afterwards.
*
* The context to destroy must have been created using
* secp256k1_context_preallocated_create or secp256k1_context_preallocated_clone.
* If the context has instead been created using secp256k1_context_create or
* secp256k1_context_clone, the behaviour is undefined. In that case,
* secp256k1_context_destroy must be used instead.
*
* If required, it is the responsibility of the caller to deallocate the block
* of memory properly after this function returns, e.g., by calling free on the
* preallocated pointer given to secp256k1_context_preallocated_create or
* secp256k1_context_preallocated_clone.
*
* Args: ctx: an existing context to destroy, constructed using
* secp256k1_context_preallocated_create or
* secp256k1_context_preallocated_clone (cannot be NULL)
*/
SECP256K1_API void secp256k1_context_preallocated_destroy(
secp256k1_context* ctx
);
#ifdef __cplusplus
}
#endif
#endif /* SECP256K1_PREALLOCATED_H */
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