mirror of
https://github.com/glebd/cocoafob.git
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Balázs Galambosi
112 lines
3.1 KiB
C
112 lines
3.1 KiB
C
/* Copyright (c) 2007 Samuel Tesla
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "encoder.h"
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size_t
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base32_encoder_last_quintent (const size_t bytes)
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{
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size_t quintets = bytes * 8 / 5;
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size_t remainder = bytes % 5;
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return remainder == 0 ? quintets : quintets + 1;
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}
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size_t
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base32_encoder_output_padding_size (const size_t bytes)
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{
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unsigned remainder = bytes % 5;
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return remainder == 0 ? 0 : (5 - remainder) * 8 / 5;
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}
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size_t
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base32_encoder_buffer_size (const size_t bytes)
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{
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return base32_encoder_last_quintent (bytes) +
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base32_encoder_output_padding_size (bytes);
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}
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static size_t
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base32_encoder_encode_bits (size_t position, const uint8_t *buffer)
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{
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size_t offset = position / 8 * 5;
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switch (position % 8)
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{
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case 0:
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return
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((buffer[offset] & 0xF8) >> 3);
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case 1:
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return
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((buffer[offset] & 0x07) << 2) +
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((buffer[offset + 1] & 0xC0) >> 6);
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case 2:
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return
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((buffer[offset + 1] & 0x3E) >> 1);
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case 3:
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return
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((buffer[offset + 1] & 0x01) << 4) +
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((buffer[offset + 2] & 0xF0) >> 4);
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case 4:
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return
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((buffer[offset + 2] & 0x0F) << 1) +
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((buffer[offset + 3] & 0x80) >> 7);
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case 5:
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return
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((buffer[offset + 3] & 0x7C) >> 2);
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case 6:
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return
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((buffer[offset + 3] & 0x03) << 3) +
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((buffer[offset + 4] & 0xE0) >> 5);
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case 7:
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return
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buffer[offset + 4] & 0x1F;
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default:
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return 0;
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}
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}
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static inline uint8_t
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base32_encoder_encode_at_position (size_t position, const uint8_t *buffer)
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{
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const char *table = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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size_t index = base32_encoder_encode_bits (position, buffer);
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return table[index];
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}
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void
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base32_encode (uint8_t *output, const size_t outputLength,
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const uint8_t *input, const size_t inputLength)
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{
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size_t i;
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size_t quintets = base32_encoder_last_quintent(inputLength);
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for (i = 0; i < quintets; i++)
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output[i] = base32_encoder_encode_at_position (i, input);
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for (i = quintets; i < outputLength; i++)
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output[i] = '=';
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}
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