Rename ffmpeg-4.2-fit to ffmpeg-4-fit

trunk/3rdparty/ffmpeg-4-fit/libavutil/hash.h

@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2013 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * @ingroup lavu_hash_generic
+ * Generic hashing API
+ */
+
+#ifndef AVUTIL_HASH_H
+#define AVUTIL_HASH_H
+
+#include <stdint.h>
+
+#include "version.h"
+
+/**
+ * @defgroup lavu_hash Hash Functions
+ * @ingroup lavu_crypto
+ * Hash functions useful in multimedia.
+ *
+ * Hash functions are widely used in multimedia, from error checking and
+ * concealment to internal regression testing. libavutil has efficient
+ * implementations of a variety of hash functions that may be useful for
+ * FFmpeg and other multimedia applications.
+ *
+ * @{
+ *
+ * @defgroup lavu_hash_generic Generic Hashing API
+ * An abstraction layer for all hash functions supported by libavutil.
+ *
+ * If your application needs to support a wide range of different hash
+ * functions, then the Generic Hashing API is for you. It provides a generic,
+ * reusable API for @ref lavu_hash "all hash functions" implemented in libavutil.
+ * If you just need to use one particular hash function, use the @ref lavu_hash
+ * "individual hash" directly.
+ *
+ * @section Sample Code
+ *
+ * A basic template for using the Generic Hashing API follows:
+ *
+ * @code
+ * struct AVHashContext *ctx = NULL;
+ * const char *hash_name = NULL;
+ * uint8_t *output_buf = NULL;
+ *
+ * // Select from a string returned by av_hash_names()
+ * hash_name = ...;
+ *
+ * // Allocate a hash context
+ * ret = av_hash_alloc(&ctx, hash_name);
+ * if (ret < 0)
+ *     return ret;
+ *
+ * // Initialize the hash context
+ * av_hash_init(ctx);
+ *
+ * // Update the hash context with data
+ * while (data_left) {
+ *     av_hash_update(ctx, data, size);
+ * }
+ *
+ * // Now we have no more data, so it is time to finalize the hash and get the
+ * // output. But we need to first allocate an output buffer. Note that you can
+ * // use any memory allocation function, including malloc(), not just
+ * // av_malloc().
+ * output_buf = av_malloc(av_hash_get_size(ctx));
+ * if (!output_buf)
+ *     return AVERROR(ENOMEM);
+ *
+ * // Finalize the hash context.
+ * // You can use any of the av_hash_final*() functions provided, for other
+ * // output formats. If you do so, be sure to adjust the memory allocation
+ * // above. See the function documentation below for the exact amount of extra
+ * // memory needed.
+ * av_hash_final(ctx, output_buffer);
+ *
+ * // Free the context
+ * av_hash_freep(&ctx);
+ * @endcode
+ *
+ * @section Hash Function-Specific Information
+ * If the CRC32 hash is selected, the #AV_CRC_32_IEEE polynomial will be
+ * used.
+ *
+ * If the Murmur3 hash is selected, the default seed will be used. See @ref
+ * lavu_murmur3_seedinfo "Murmur3" for more information.
+ *
+ * @{
+ */
+
+/**
+ * @example ffhash.c
+ * This example is a simple command line application that takes one or more
+ * arguments. It demonstrates a typical use of the hashing API with allocation,
+ * initialization, updating, and finalizing.
+ */
+
+struct AVHashContext;
+
+/**
+ * Allocate a hash context for the algorithm specified by name.
+ *
+ * @return  >= 0 for success, a negative error code for failure
+ *
+ * @note The context is not initialized after a call to this function; you must
+ * call av_hash_init() to do so.
+ */
+int av_hash_alloc(struct AVHashContext **ctx, const char *name);
+
+/**
+ * Get the names of available hash algorithms.
+ *
+ * This function can be used to enumerate the algorithms.
+ *
+ * @param[in] i  Index of the hash algorithm, starting from 0
+ * @return       Pointer to a static string or `NULL` if `i` is out of range
+ */
+const char *av_hash_names(int i);
+
+/**
+ * Get the name of the algorithm corresponding to the given hash context.
+ */
+const char *av_hash_get_name(const struct AVHashContext *ctx);
+
+/**
+ * Maximum value that av_hash_get_size() will currently return.
+ *
+ * You can use this if you absolutely want or need to use static allocation for
+ * the output buffer and are fine with not supporting hashes newly added to
+ * libavutil without recompilation.
+ *
+ * @warning
+ * Adding new hashes with larger sizes, and increasing the macro while doing
+ * so, will not be considered an ABI change. To prevent your code from
+ * overflowing a buffer, either dynamically allocate the output buffer with
+ * av_hash_get_size(), or limit your use of the Hashing API to hashes that are
+ * already in FFmpeg during the time of compilation.
+ */
+#define AV_HASH_MAX_SIZE 64
+
+/**
+ * Get the size of the resulting hash value in bytes.
+ *
+ * The maximum value this function will currently return is available as macro
+ * #AV_HASH_MAX_SIZE.
+ *
+ * @param[in]     ctx Hash context
+ * @return            Size of the hash value in bytes
+ */
+int av_hash_get_size(const struct AVHashContext *ctx);
+
+/**
+ * Initialize or reset a hash context.
+ *
+ * @param[in,out] ctx Hash context
+ */
+void av_hash_init(struct AVHashContext *ctx);
+
+/**
+ * Update a hash context with additional data.
+ *
+ * @param[in,out] ctx Hash context
+ * @param[in]     src Data to be added to the hash context
+ * @param[in]     len Size of the additional data
+ */
+#if FF_API_CRYPTO_SIZE_T
+void av_hash_update(struct AVHashContext *ctx, const uint8_t *src, int len);
+#else
+void av_hash_update(struct AVHashContext *ctx, const uint8_t *src, size_t len);
+#endif
+
+/**
+ * Finalize a hash context and compute the actual hash value.
+ *
+ * The minimum size of `dst` buffer is given by av_hash_get_size() or
+ * #AV_HASH_MAX_SIZE. The use of the latter macro is discouraged.
+ *
+ * It is not safe to update or finalize a hash context again, if it has already
+ * been finalized.
+ *
+ * @param[in,out] ctx Hash context
+ * @param[out]    dst Where the final hash value will be stored
+ *
+ * @see av_hash_final_bin() provides an alternative API
+ */
+void av_hash_final(struct AVHashContext *ctx, uint8_t *dst);
+
+/**
+ * Finalize a hash context and store the actual hash value in a buffer.
+ *
+ * It is not safe to update or finalize a hash context again, if it has already
+ * been finalized.
+ *
+ * If `size` is smaller than the hash size (given by av_hash_get_size()), the
+ * hash is truncated; if size is larger, the buffer is padded with 0.
+ *
+ * @param[in,out] ctx  Hash context
+ * @param[out]    dst  Where the final hash value will be stored
+ * @param[in]     size Number of bytes to write to `dst`
+ */
+void av_hash_final_bin(struct AVHashContext *ctx, uint8_t *dst, int size);
+
+/**
+ * Finalize a hash context and store the hexadecimal representation of the
+ * actual hash value as a string.
+ *
+ * It is not safe to update or finalize a hash context again, if it has already
+ * been finalized.
+ *
+ * The string is always 0-terminated.
+ *
+ * If `size` is smaller than `2 * hash_size + 1`, where `hash_size` is the
+ * value returned by av_hash_get_size(), the string will be truncated.
+ *
+ * @param[in,out] ctx  Hash context
+ * @param[out]    dst  Where the string will be stored
+ * @param[in]     size Maximum number of bytes to write to `dst`
+ */
+void av_hash_final_hex(struct AVHashContext *ctx, uint8_t *dst, int size);
+
+/**
+ * Finalize a hash context and store the Base64 representation of the
+ * actual hash value as a string.
+ *
+ * It is not safe to update or finalize a hash context again, if it has already
+ * been finalized.
+ *
+ * The string is always 0-terminated.
+ *
+ * If `size` is smaller than AV_BASE64_SIZE(hash_size), where `hash_size` is
+ * the value returned by av_hash_get_size(), the string will be truncated.
+ *
+ * @param[in,out] ctx  Hash context
+ * @param[out]    dst  Where the final hash value will be stored
+ * @param[in]     size Maximum number of bytes to write to `dst`
+ */
+void av_hash_final_b64(struct AVHashContext *ctx, uint8_t *dst, int size);
+
+/**
+ * Free hash context and set hash context pointer to `NULL`.
+ *
+ * @param[in,out] ctx  Pointer to hash context
+ */
+void av_hash_freep(struct AVHashContext **ctx);
+
+/**
+ * @}
+ * @}
+ */
+
+#endif /* AVUTIL_HASH_H */