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* fnv1a.c : routines to create checksums derived from FNV-1a
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* ====================================================================
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* ====================================================================
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#define APR_WANT_BYTEFUNC
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#include "private/svn_subr_private.h"
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* See http://www.isthe.com/chongo/tech/comp/fnv/ for more info on FNV-1
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/* FNV-1 32 bit constants taken from
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* http://www.isthe.com/chongo/tech/comp/fnv/
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#define FNV1_PRIME_32 0x01000193
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#define FNV1_BASE_32 2166136261U
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/* FNV-1a core implementation returning a 32 bit checksum over the first
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* LEN bytes in INPUT. HASH is the checksum over preceding data (if any).
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fnv1a_32(apr_uint32_t hash, const void *input, apr_size_t len)
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const unsigned char *data = input;
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const unsigned char *end = data + len;
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for (; data != end; ++data)
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hash *= FNV1_PRIME_32;
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/* Number of interleaved FVN-1a checksums we calculate for the modified
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/* FNV-1a core implementation updating 4 interleaved checksums in HASHES
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* over the first LEN bytes in INPUT. This will only process multiples
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* of 4 and return the number of bytes processed. LEN - ReturnValue < 4.
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fnv1a_32x4(apr_uint32_t hashes[SCALING], const void *input, apr_size_t len)
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/* calculate SCALING interleaved FNV-1a hashes while the input
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const unsigned char *data = input;
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const unsigned char *end = data + len;
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for (; data + SCALING <= end; data += SCALING)
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hashes[0] *= FNV1_PRIME_32;
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hashes[1] *= FNV1_PRIME_32;
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hashes[2] *= FNV1_PRIME_32;
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hashes[3] *= FNV1_PRIME_32;
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return data - (const unsigned char *)input;
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/* Combine interleaved HASHES plus LEN bytes from INPUT into a single
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* 32 bit hash value and return that. LEN must be < 4.
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finalize_fnv1a_32x4(apr_uint32_t hashes[SCALING],
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char final_data[sizeof(apr_uint32_t) * SCALING + SCALING - 1];
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assert(len < SCALING);
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for (i = 0; i < SCALING; ++i)
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hashes[i] = htonl(hashes[i]);
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/* run FNV-1a over the interleaved checksums plus the remaining
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(odd-lotted) input data */
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memcpy(final_data, hashes, sizeof(apr_uint32_t) * SCALING);
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memcpy(final_data + sizeof(apr_uint32_t) * SCALING, input, len);
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return fnv1a_32(FNV1_BASE_32,
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sizeof(apr_uint32_t) * SCALING + len);
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svn__fnv1a_32(const void *input, apr_size_t len)
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return fnv1a_32(FNV1_BASE_32, input, len);
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svn__fnv1a_32x4(const void *input, apr_size_t len)
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apr_uint32_t hashes[SCALING]
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= { FNV1_BASE_32, FNV1_BASE_32, FNV1_BASE_32, FNV1_BASE_32 };
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apr_size_t processed = fnv1a_32x4(hashes, input, len);
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return finalize_fnv1a_32x4(hashes,
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(const char *)input + processed,
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svn__fnv1a_32x4_raw(apr_uint32_t hashes[4],
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apr_size_t processed;
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for (i = 0; i < SCALING; ++i)
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hashes[i] = FNV1_BASE_32;
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/* Process full 16 byte chunks. */
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processed = fnv1a_32x4(hashes, input, len);
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/* Fold the remainder (if any) into the first hash. */
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hashes[0] = fnv1a_32(hashes[0], (const char *)input + processed,
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struct svn_fnv1a_32__context_t
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svn_fnv1a_32__context_t *
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svn_fnv1a_32__context_create(apr_pool_t *pool)
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svn_fnv1a_32__context_t *context = apr_palloc(pool, sizeof(*context));
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context->hash = FNV1_BASE_32;
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svn_fnv1a_32__update(svn_fnv1a_32__context_t *context,
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context->hash = fnv1a_32(context->hash, data, len);
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svn_fnv1a_32__finalize(svn_fnv1a_32__context_t *context)
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return context->hash;
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struct svn_fnv1a_32x4__context_t
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apr_uint32_t hashes[SCALING];
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char buffer[SCALING];
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svn_fnv1a_32x4__context_t *
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svn_fnv1a_32x4__context_create(apr_pool_t *pool)
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svn_fnv1a_32x4__context_t *context = apr_palloc(pool, sizeof(*context));
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context->hashes[0] = FNV1_BASE_32;
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context->hashes[1] = FNV1_BASE_32;
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context->hashes[2] = FNV1_BASE_32;
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context->hashes[3] = FNV1_BASE_32;
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context->buffered = 0;
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svn_fnv1a_32x4__update(svn_fnv1a_32x4__context_t *context,
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apr_size_t processed;
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if (context->buffered)
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apr_size_t to_copy = SCALING - context->buffered;
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memcpy(context->buffer + context->buffered, data, len);
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context->buffered += len;
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memcpy(context->buffer + context->buffered, data, to_copy);
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data = (const char *)data + to_copy;
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fnv1a_32x4(context->hashes, context->buffer, SCALING);
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context->buffered = 0;
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processed = fnv1a_32x4(context->hashes, data, len);
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if (processed != len)
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context->buffered = len - processed;
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memcpy(context->buffer,
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(const char*)data + processed,
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svn_fnv1a_32x4__finalize(svn_fnv1a_32x4__context_t *context)
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return finalize_fnv1a_32x4(context->hashes,