diff options
Diffstat (limited to 'src/shared/libosmocore/include/osmocom/core/conv.h')
| -rw-r--r-- | src/shared/libosmocore/include/osmocom/core/conv.h | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/src/shared/libosmocore/include/osmocom/core/conv.h b/src/shared/libosmocore/include/osmocom/core/conv.h new file mode 100644 index 00000000..e5b2a975 --- /dev/null +++ b/src/shared/libosmocore/include/osmocom/core/conv.h @@ -0,0 +1,146 @@ +/* + * conv.h + * + * Copyright (C) 2011 Sylvain Munaut <tnt@246tNt.com> + * + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +/*! \defgroup conv Convolutional encoding and decoding routines + * @{ + */ + +/*! \file conv.h + * \file Osmocom convolutional encoder and decoder + */ + +#ifndef __OSMO_CONV_H__ +#define __OSMO_CONV_H__ + +#include <stdint.h> + +#include <osmocom/core/bits.h> + +/*! \brief possibe termination types + * + * The termination type will determine which state the encoder/decoder + * can start/end with. This is mostly taken care of in the high level API + * call. So if you use the low level API, you must take care of making the + * proper calls yourself. + */ +enum osmo_conv_term { + CONV_TERM_FLUSH = 0, /*!< \brief Flush encoder state */ + CONV_TERM_TRUNCATION, /*!< \brief Direct truncation */ + CONV_TERM_TAIL_BITING, /*!< \brief Tail biting */ +}; + +/*! \brief structure describing a given convolutional code + * + * The only required fields are N,K and the next_output/next_state arrays. The + * other can be left to default value of zero depending on what the code does. + * If 'len' is left at 0 then only the low level API can be used. + */ +struct osmo_conv_code { + int N; /*!< \brief Inverse of code rate */ + int K; /*!< \brief Constraint length */ + int len; /*!< \brief # of data bits */ + + enum osmo_conv_term term; /*!< \brief Termination type */ + + const uint8_t (*next_output)[2];/*!< \brief Next output array */ + const uint8_t (*next_state)[2]; /*!< \brief Next state array */ + + const uint8_t *next_term_output;/*!< \brief Flush termination output */ + const uint8_t *next_term_state; /*!< \brief Flush termination state */ + + const int *puncture; /*!< \brief Punctured bits indexes */ +}; + + +/* Common */ + +int osmo_conv_get_input_length(const struct osmo_conv_code *code, int len); +int osmo_conv_get_output_length(const struct osmo_conv_code *code, int len); + + +/* Encoding */ + + /* Low level API */ + +/*! \brief convolutional encoder state */ +struct osmo_conv_encoder { + const struct osmo_conv_code *code; /*!< \brief for which code? */ + int i_idx; /*!< \brief Next input bit index */ + int p_idx; /*!< \brief Current puncture index */ + uint8_t state; /*!< \brief Current state */ +}; + +void osmo_conv_encode_init(struct osmo_conv_encoder *encoder, + const struct osmo_conv_code *code); +void osmo_conv_encode_load_state(struct osmo_conv_encoder *encoder, + const ubit_t *input); +int osmo_conv_encode_raw(struct osmo_conv_encoder *encoder, + const ubit_t *input, ubit_t *output, int n); +int osmo_conv_encode_flush(struct osmo_conv_encoder *encoder, ubit_t *output); + + /* All-in-one */ +int osmo_conv_encode(const struct osmo_conv_code *code, + const ubit_t *input, ubit_t *output); + + +/* Decoding */ + + /* Low level API */ + +/*! \brief convolutional decoder state */ +struct osmo_conv_decoder { + const struct osmo_conv_code *code; /*!< \brief for which code? */ + + int n_states; /*!< \brief number of states */ + + int len; /*!< \brief Max o_idx (excl. termination) */ + + int o_idx; /*!< \brief output index */ + int p_idx; /*!< \brief puncture index */ + + unsigned int *ae; /*!< \brief accumulated error */ + unsigned int *ae_next; /*!< \brief next accumulated error (tmp in scan) */ + uint8_t *state_history; /*!< \brief state history [len][n_states] */ +}; + +void osmo_conv_decode_init(struct osmo_conv_decoder *decoder, + const struct osmo_conv_code *code, + int len, int start_state); +void osmo_conv_decode_reset(struct osmo_conv_decoder *decoder, int start_state); +void osmo_conv_decode_rewind(struct osmo_conv_decoder *decoder); +void osmo_conv_decode_deinit(struct osmo_conv_decoder *decoder); + +int osmo_conv_decode_scan(struct osmo_conv_decoder *decoder, + const sbit_t *input, int n); +int osmo_conv_decode_flush(struct osmo_conv_decoder *decoder, + const sbit_t *input); +int osmo_conv_decode_get_output(struct osmo_conv_decoder *decoder, + ubit_t *output, int has_flush, int end_state); + + /* All-in-one */ +int osmo_conv_decode(const struct osmo_conv_code *code, + const sbit_t *input, ubit_t *output); + + +/*! @} */ + +#endif /* __OSMO_CONV_H__ */ |