Lesson 35 - Get Compute Auth Token Working
This commit is contained in:
Norman Lansing
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#ifndef AWS_COMPRESSION_HUFFMAN_H
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#define AWS_COMPRESSION_HUFFMAN_H
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/**
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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* SPDX-License-Identifier: Apache-2.0.
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*/
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#include <aws/compression/compression.h>
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#include <aws/common/byte_buf.h>
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AWS_PUSH_SANE_WARNING_LEVEL
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/**
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* Represents an encoded code
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*/
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struct aws_huffman_code {
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/**
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* The value of the code
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* \note The pattern is stored in the least significant bits
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*/
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uint32_t pattern;
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/** The number of bits in pattern to use */
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uint8_t num_bits;
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};
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/**
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* Function used to encode a single symbol to an aws_huffman_code
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*
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* \param[in] symbol The symbol to encode
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* \param[in] userdata Optional userdata (aws_huffman_symbol_coder.userdata)
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*
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* \returns The code representing the symbol. If this symbol is not recognized,
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* return a code with num_bits set to 0.
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*/
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typedef struct aws_huffman_code(aws_huffman_symbol_encoder_fn)(uint8_t symbol, void *userdata);
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/**
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* Function used to decode a code into a symbol
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*
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* \param[in] bits The bits to attept to decode a symbol from
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* \param[out] symbol The symbol found. Do not write to if no valid symbol
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* found \param[in] userdata Optional userdata
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* (aws_huffman_symbol_coder.userdata)
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*
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* \returns The number of bits read from bits
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*/
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typedef uint8_t(aws_huffman_symbol_decoder_fn)(uint32_t bits, uint8_t *symbol, void *userdata);
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/**
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* Structure used to define how symbols are encoded and decoded
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*/
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struct aws_huffman_symbol_coder {
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aws_huffman_symbol_encoder_fn *encode;
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aws_huffman_symbol_decoder_fn *decode;
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void *userdata;
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};
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/**
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* Structure used for persistent encoding.
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* Allows for reading from or writing to incomplete buffers.
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*/
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struct aws_huffman_encoder {
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/* Params */
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struct aws_huffman_symbol_coder *coder;
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uint8_t eos_padding;
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/* State */
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struct aws_huffman_code overflow_bits;
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};
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/**
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* Structure used for persistent decoding.
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* Allows for reading from or writing to incomplete buffers.
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*/
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struct aws_huffman_decoder {
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/* Param */
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struct aws_huffman_symbol_coder *coder;
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bool allow_growth;
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/* State */
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uint64_t working_bits;
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uint8_t num_bits;
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};
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AWS_EXTERN_C_BEGIN
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/**
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* Initialize a encoder object with a symbol coder.
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*/
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AWS_COMPRESSION_API
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void aws_huffman_encoder_init(struct aws_huffman_encoder *encoder, struct aws_huffman_symbol_coder *coder);
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/**
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* Resets a decoder for use with a new binary stream
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*/
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AWS_COMPRESSION_API
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void aws_huffman_encoder_reset(struct aws_huffman_encoder *encoder);
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/**
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* Initialize a decoder object with a symbol coder.
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*/
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AWS_COMPRESSION_API
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void aws_huffman_decoder_init(struct aws_huffman_decoder *decoder, struct aws_huffman_symbol_coder *coder);
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/**
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* Resets a decoder for use with a new binary stream
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*/
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AWS_COMPRESSION_API
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void aws_huffman_decoder_reset(struct aws_huffman_decoder *decoder);
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/**
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* Get the byte length of to_encode post-encoding.
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*
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* \param[in] encoder The encoder object to use
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* \param[in] to_encode The symbol buffer to encode
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*
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* \return The length of the encoded string.
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*/
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AWS_COMPRESSION_API
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size_t aws_huffman_get_encoded_length(struct aws_huffman_encoder *encoder, struct aws_byte_cursor to_encode);
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/**
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* Encode a symbol buffer into the output buffer.
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*
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* \param[in] encoder The encoder object to use
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* \param[in] to_encode The symbol buffer to encode
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* \param[in] output The buffer to write encoded bytes to
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*
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* \return AWS_OP_SUCCESS if encoding is successful, AWS_OP_ERR otherwise
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*/
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AWS_COMPRESSION_API
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int aws_huffman_encode(
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struct aws_huffman_encoder *encoder,
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struct aws_byte_cursor *to_encode,
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struct aws_byte_buf *output);
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/**
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* Decodes a byte buffer into the provided symbol array.
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*
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* \param[in] decoder The decoder object to use
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* \param[in] to_decode The encoded byte buffer to read from
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* \param[in] output The buffer to write decoded symbols to.
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* If decoder is set to allow growth, capacity will be increased when necessary.
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*
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* \return AWS_OP_SUCCESS if encoding is successful, AWS_OP_ERR otherwise
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*/
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AWS_COMPRESSION_API
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int aws_huffman_decode(
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struct aws_huffman_decoder *decoder,
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struct aws_byte_cursor *to_decode,
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struct aws_byte_buf *output);
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/**
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* Set whether or not to increase capacity when the output buffer fills up while decoding.
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* This is false by default.
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*/
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AWS_COMPRESSION_API
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void aws_huffman_decoder_allow_growth(struct aws_huffman_decoder *decoder, bool allow_growth);
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AWS_EXTERN_C_END
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AWS_POP_SANE_WARNING_LEVEL
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#endif /* AWS_COMPRESSION_HUFFMAN_H */
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