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