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108 lines
4.2 KiB
Plaintext
108 lines
4.2 KiB
Plaintext
// User include file for libfec
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// Copyright 2004, 2014 Phil Karn, KA9Q
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// May be used under the terms of the GNU Lesser General Public License (LGPL)
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#ifndef _FEC_H_
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#define _FEC_H_
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// r=1/2 k=7 convolutional encoder polynomials
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// The NASA-DSN convention is to use V27POLYA inverted, then V27POLYB
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// The CCSDS/NASA-GSFC convention is to use V27POLYB, then V27POLYA inverted
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#define V27POLYA 0x6d
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#define V27POLYB 0x4f
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void *create_viterbi27(int len);
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int init_viterbi27(void *vp,int starting_state);
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int update_viterbi27_blk(void *vp,unsigned char sym[],int npairs);
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int chainback_viterbi27(void *vp, unsigned char *data,unsigned int nbits,unsigned int endstate);
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void delete_viterbi27(void *vp);
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// r=1/2 k=9 convolutional encoder polynomials
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#define V29POLYA 0x1af
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#define V29POLYB 0x11d
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void *create_viterbi29(int len);
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int init_viterbi29(void *vp,int starting_state);
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int update_viterbi29_blk(void *vp,unsigned char syms[],int nbits);
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int chainback_viterbi29(void *vp, unsigned char *data,unsigned int nbits,unsigned int endstate);
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void delete_viterbi29(void *vp);
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// r=1/3 k=9 convolutional encoder polynomials
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#define V39POLYA 0x1ed
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#define V39POLYB 0x19b
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#define V39POLYC 0x127
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void *create_viterbi39(int len);
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int init_viterbi39(void *vp,int starting_state);
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int update_viterbi39_blk(void *vp,unsigned char syms[],int nbits);
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int chainback_viterbi39(void *vp, unsigned char *data,unsigned int nbits,unsigned int endstate);
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void delete_viterbi39(void *vp);
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// r=1/6 k=15 Cassini convolutional encoder polynomials without symbol inversion
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// dfree = 56
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// These bits may be left-right flipped from some textbook representations;
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// here I have the bits entering the shift register from the right (low) end
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// Some other spacecraft use the same code, but with the polynomials in a different order.
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// E.g., Mars Pathfinder and STEREO swap POLYC and POLYD. All use alternate symbol inversion.
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#define V615POLYA 042631
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#define V615POLYB 047245
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#define V615POLYC 056507
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#define V615POLYD 073363
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#define V615POLYE 077267
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#define V615POLYF 064537
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void *create_viterbi615(int len);
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int init_viterbi615(void *vp,int starting_state);
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int update_viterbi615_blk(void *vp,unsigned char *syms,int nbits);
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int chainback_viterbi615(void *vp, unsigned char *data,unsigned int nbits,unsigned int endstate);
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void delete_viterbi615(void *vp);
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// r=1/2 k=24 MCQLI-24 r=1/2 k=24 convolutional code for ISEE-3/ICE, launched 1978
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// Obviously this code was originally intended for sequential decoding, but here's
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// a monster Viterbi decoder for this code!
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// The ref gives the polynomials as 073353367 and 053353367 (octal)
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// Shortened from MCQLI-48
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#define V224POLY1 073665667
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#define V224POLY2 073665665
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#define G1FLIP 0
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#define G2FLIP 1 // Invert the second symbol
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void *create_viterbi224(int len);
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int init_viterbi224(void *p,int starting_state);
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int update_viterbi224_blk(void *p,const unsigned char *syms,int nbits);
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int chainback_viterbi224(void *p,unsigned char *data,unsigned int nbits,unsigned int endstate);
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void delete_viterbi224(void *p);
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// General purpose RS codec, 8-bit symbols
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void encode_rs_char(void *rs,unsigned char *data,unsigned char *parity);
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int decode_rs_char(void *rs,unsigned char *data,int *eras_pos,
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int no_eras);
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void *init_rs_char(int symsize,int gfpoly,
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int fcr,int prim,int nroots,
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int pad);
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void free_rs_char(void *rs);
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// General purpose RS codec, integer symbols
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void encode_rs_int(void *rs,int *data,int *parity);
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int decode_rs_int(void *rs,int *data,int *eras_pos,int no_eras);
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void *init_rs_int(int symsize,int gfpoly,int fcr,
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int prim,int nroots,int pad);
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void free_rs_int(void *rs);
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// CCSDS standard (255,223) RS codec with conventional (*not* dual-basis) representation
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void encode_rs_8(unsigned char *data,unsigned char *parity,int pad);
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int decode_rs_8(unsigned char *data,int *eras_pos,int no_eras,int pad);
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// CCSDS standard (255,223) RS codec with dual-basis symbol representation
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void encode_rs_ccsds(unsigned char *data,unsigned char *parity,int pad);
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int decode_rs_ccsds(unsigned char *data,int *eras_pos,int no_eras,int pad);
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// Tables to map from conventional->dual (Taltab) and dual->conventional (Tal1tab) bases
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extern unsigned char Taltab[],Tal1tab[];
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#endif /* _FEC_H_ */
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