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#ifndef _MH_SHA256_H_
#define _MH_SHA256_H_

/**
 *  @file mh_sha256.h
 *  @brief mh_sha256 function prototypes and structures
 *
 *  Interface for mh_sha256 functions
 *
 * <b> mh_sha256  Init-Update..Update-Finalize </b>
 *
 * This file defines the interface to optimized functions used in mh_sha256.
 * The definition of multi-hash SHA256(mh_sha256, for short) is: Pad the buffer
 * in SHA256 style until the total length is a multiple of 4*16*16
 * (words-width * parallel-segments * block-size); Hash the buffer in
 * parallel, generating digests of 4*16*8 (words-width*parallel-segments*
 * digest-size); Treat the set of digests as another data buffer, and
 * generate a final SHA256 digest for it.
 *
 *
 * Example
 * \code
 * uint32_t mh_sha256_digest[SHA256_DIGEST_WORDS];
 * struct mh_sha256_ctx *ctx;
 *
 * ctx = malloc(sizeof(struct mh_sha256_ctx));
 * mh_sha256_init(ctx);
 * mh_sha256_update(ctx, buff, block_len);
 * mh_sha256_finalize(ctx, mh_sha256_digest);
 * \endcode
 */

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif


// External Interface Definition
#define HASH_SEGS					16
#define SHA256_BLOCK_SIZE				64
#define MH_SHA256_BLOCK_SIZE   (HASH_SEGS * SHA256_BLOCK_SIZE)
#define SHA256_DIGEST_WORDS				 8
#define AVX512_ALIGNED					64

/** @brief Holds info describing a single mh_sha256
 *
 * It is better to use heap to allocate this data structure to avoid stack overflow.
 *
*/
struct mh_sha256_ctx {
	uint32_t  mh_sha256_digest[SHA256_DIGEST_WORDS]; //!< the digest of multi-hash SHA256

	uint64_t  total_length;
	//!<  Parameters for update feature, describe the lengths of input buffers in bytes
	uint8_t   partial_block_buffer [MH_SHA256_BLOCK_SIZE * 2];
	//!<  Padding the tail of input data for SHA256
	uint8_t   mh_sha256_interim_digests[sizeof(uint32_t) * SHA256_DIGEST_WORDS * HASH_SEGS];
	//!<  Storing the SHA256 interim digests of  all 16 segments. Each time, it will be copied to stack for 64-byte alignment purpose.
	uint8_t   frame_buffer[MH_SHA256_BLOCK_SIZE + AVX512_ALIGNED];
	//!<  Re-structure sha256 block data from different segments to fit big endian. Use AVX512_ALIGNED for 64-byte alignment purpose.
};

/**
 *  @enum mh_sha256_ctx_error
 *  @brief CTX error flags
 */
enum mh_sha256_ctx_error{
	MH_SHA256_CTX_ERROR_NONE			=  0, //!< MH_SHA256_CTX_ERROR_NONE
	MH_SHA256_CTX_ERROR_NULL			= -1, //!< MH_SHA256_CTX_ERROR_NULL
};


/*******************************************************************
 * mh_sha256 API function prototypes
 ******************************************************************/

/**
 * @brief Initialize the mh_sha256_ctx structure.
 *
 * @param  ctx Structure holding mh_sha256 info
 * @returns int Return 0 if the function runs without errors
 */
int mh_sha256_init (struct mh_sha256_ctx* ctx);

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * This function determines what instruction sets are enabled and selects the
 * appropriate version at runtime.
 *
 * @param  ctx Structure holding mh_sha256 info
 * @param  buffer Pointer to buffer to be processed
 * @param  len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 */
int mh_sha256_update (struct mh_sha256_ctx * ctx, const void* buffer, uint32_t len);

/**
 * @brief Finalize the message digests for multi-hash sha256.
 *
 * Place the message digest in mh_sha256_digest which must have enough space
 * for the outputs.
 * This function determines what instruction sets are enabled and selects the
 * appropriate version at runtime.
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 */
int mh_sha256_finalize (struct mh_sha256_ctx* ctx, void* mh_sha256_digest);

/*******************************************************************
 * multi-types of mh_sha256 internal API
 *
 * XXXX		The multi-binary version
 * XXXX_base	The C code version which used to display the algorithm
 * XXXX_sse	The version uses a ASM function optimized for SSE
 * XXXX_avx	The version uses a ASM function optimized for AVX
 * XXXX_avx2	The version uses a ASM function optimized for AVX2
 * XXXX_avx512	The version uses a ASM function optimized for AVX512
 *
 ******************************************************************/

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * Base update() function that does not require SIMD support.
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   buffer Pointer to buffer to be processed
 * @param   len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_update_base (struct mh_sha256_ctx* ctx, const void* buffer, uint32_t len);

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * @requires SSE
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   buffer Pointer to buffer to be processed
 * @param   len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_update_sse (struct mh_sha256_ctx * ctx,
						const void* buffer, uint32_t len);

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * @requires AVX
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   buffer Pointer to buffer to be processed
 * @param   len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_update_avx (struct mh_sha256_ctx * ctx,
						const void* buffer, uint32_t len);

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * @requires AVX2
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   buffer Pointer to buffer to be processed
 * @param   len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_update_avx2 (struct mh_sha256_ctx * ctx,
						const void* buffer, uint32_t len);

/**
 * @brief Multi-hash sha256 update.
 *
 * Can be called repeatedly to update hashes with new input data.
 * @requires AVX512
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   buffer Pointer to buffer to be processed
 * @param   len Length of buffer (in bytes) to be processed
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_update_avx512 (struct mh_sha256_ctx * ctx,
						const void* buffer, uint32_t len);


/**
  * @brief Finalize the message digests for multi-hash sha256.
 *
 * Place the message digests in mh_sha256_digest,
 * which must have enough space for the outputs.
 * Base Finalize() function that does not require SIMD support.
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_finalize_base (struct mh_sha256_ctx* ctx,
						void* mh_sha256_digest);

/**
 * @brief Finalize the message digests for combined multi-hash and murmur.
 *
 * Place the message digest in mh_sha256_digest which must have enough space
 * for the outputs.
 *
 * @requires SSE
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_finalize_sse (struct mh_sha256_ctx* ctx,
						void* mh_sha256_digest);

/**
 * @brief Finalize the message digests for combined multi-hash and murmur.
 *
 * Place the message digest in mh_sha256_digest which must have enough space
 * for the outputs.
 *
 * @requires AVX
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_finalize_avx (struct mh_sha256_ctx* ctx,
						void* mh_sha256_digest);

/**
 * @brief Finalize the message digests for combined multi-hash and murmur.
 *
 * Place the message digest in mh_sha256_digest which must have enough space
 * for the outputs.
 *
 * @requires AVX2
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_finalize_avx2 (struct mh_sha256_ctx* ctx,
						void* mh_sha256_digest);

/**
 * @brief Finalize the message digests for combined multi-hash and murmur.
 *
 * Place the message digest in mh_sha256_digest which must have enough space
 * for the outputs.
 *
 * @requires AVX512
 *
 * @param   ctx Structure holding mh_sha256 info
 * @param   mh_sha256_digest The digest of mh_sha256
 * @returns int Return 0 if the function runs without errors
 *
 */
int mh_sha256_finalize_avx512 (struct mh_sha256_ctx* ctx,
						void* mh_sha256_digest);

#ifdef __cplusplus
}
#endif

#endif