/**
 * @file md5.h
 *
 * Copyright (c) 2021 Semidrive Semiconductor.
 * All rights reserved.
 *
 * Description:compute the md5 of a data stream
 */

#ifndef __MD5_H
#define __MD5_H

#if defined(__cplusplus)
extern "C" {
#endif

#include <compiler.h>

#define MD5_LEN 16

struct MD5Context {
    unsigned int buf[4];
    unsigned int bits[2];
    union {
        unsigned char in[64];
        unsigned int in32[16];
    };
};

/**
 * @brief Initialize the MD5 context.
 *
 * This function initializes the MD5 context by setting the initial values of
 * the buffer and bit count. The buffer values are set to the predefined
 * constants of the MD5 algorithm, and the bit count is set to zero.
 *
 * @param ctx Pointer to the MD5 context structure to be initialized.
 */
void MD5Init(struct MD5Context *ctx);

/**
 * @brief Update the MD5 context with new data.
 *
 * This function updates the MD5 context with the given data buffer.
 * It processes the data in chunks of 64 bytes, updating the context's bit count
 * and calling the MD5Transform function as necessary.
 *
 * @param ctx Pointer to the MD5 context structure.
 * @param buf Pointer to the input data buffer.
 * @param len Length of the input data buffer in bytes.
 */
void MD5Update(struct MD5Context *ctx, unsigned char const *buf, unsigned len);

/**
 * @brief Finalize the MD5 hash computation.
 *
 * This function finalizes the MD5 hash computation by padding the remaining
 * data, appending the bit count, and performing the final MD5 transformation.
 * The resulting hash is stored in the provided digest buffer.
 *
 * @param digest Pointer to the buffer where the 16-byte MD5 digest will be
 * stored.
 * @param ctx Pointer to the MD5 context structure containing the current state
 * of the hash computation.
 */
void MD5Final(unsigned char digest[16], struct MD5Context *ctx);

/**
 * @brief Calculate the MD5 hash of the input data.
 *
 * This function takes an input buffer and its length, and calculates the MD5
 * hash of the data. The resulting 16-byte MD5 hash is stored in the output
 * buffer.
 *
 * @param input Pointer to the input data buffer.
 * @param len Length of the input data buffer in bytes.
 * @param output Pointer to the buffer where the 16-byte MD5 hash will be
 * stored.
 */
void md5(const unsigned char *input, const int len, unsigned char output[16]);

#if defined(__cplusplus)
}
#endif

#endif