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| Rev | Author | Line No. | Line |
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| 10 | reyssat | 1 | /* Copyright (C) 1998-2003 XIAO, Gang of Universite de Nice - Sophia Antipolis |
| 2 | * |
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| 3 | * This program is free software; you can redistribute it and/or modify |
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| 4 | * it under the terms of the GNU General Public License as published by |
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| 5 | * the Free Software Foundation; either version 2 of the License, or |
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| 6 | * (at your option) any later version. |
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| 7 | * |
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| 8 | * This program is distributed in the hope that it will be useful, |
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| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 11 | * GNU General Public License for more details. |
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| 12 | * |
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| 13 | * You should have received a copy of the GNU General Public License |
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| 14 | * along with this program; if not, write to the Free Software |
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| 15 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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| 16 | */ |
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| 17 | |||
| 18 | /* This program generates cyclic code from a polynomial |
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| 19 | * defined over a prime field. |
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| 20 | * It does not check whether the polynomial is primitive or irreducible. |
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| 7676 | bpr | 21 | * Accepted parameter: 3 words. |
| 10 | reyssat | 22 | * Word 1: field characteristics, limited to 2,3,5,7. |
| 23 | * Word 2: The polynomial coefficients (except the leading one, from |
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| 7676 | bpr | 24 | lower degree to higher) |
| 10 | reyssat | 25 | * Word 3: The starting status (starting from the first bit). |
| 26 | */ |
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| 27 | |||
| 28 | #include "../wims.h" |
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| 29 | |||
| 30 | #define MAX_DEGREE 256 |
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| 31 | #define MAX_LENGTH 1024000 |
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| 32 | |||
| 33 | int ch,degree,length; |
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| 34 | char poly[MAX_DEGREE], chain[MAX_DEGREE]; |
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| 35 | |||
| 36 | void errorquit(char *msg) |
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| 37 | { |
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| 38 | fprintf(stderr,"%s\n",msg); exit(1); |
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| 39 | } |
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| 40 | |||
| 7676 | bpr | 41 | /* Points to the end of the word */ |
| 10 | reyssat | 42 | char *find_word_end(char *p) |
| 43 | { |
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| 44 | int i; |
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| 45 | for(i=0;!isspace(*p) && *p!=0 && i<MAX_LINELEN; p++,i++); |
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| 46 | return p; |
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| 47 | } |
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| 48 | |||
| 7676 | bpr | 49 | /* Strips leading spaces */ |
| 10 | reyssat | 50 | char *find_word_start(char *p) |
| 51 | { |
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| 52 | int i; |
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| 53 | for(i=0; isspace(*p) && i<MAX_LINELEN; p++,i++); |
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| 54 | return p; |
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| 55 | } |
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| 56 | |||
| 57 | int main(int argc, char *argv[]) |
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| 58 | { |
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| 59 | char *parm, *p1, *p2, c1, c2; |
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| 60 | char pbuf[1024]; |
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| 61 | int i,j,k; |
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| 62 | double dt; |
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| 7676 | bpr | 63 | |
| 10 | reyssat | 64 | parm=getenv("wims_exec_parm"); |
| 65 | if(parm==NULL || *parm==0) errorquit("no_parameter"); |
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| 66 | snprintf(pbuf,sizeof(pbuf),"%s",parm); |
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| 67 | p1=find_word_start(pbuf); p2=find_word_end(p1); |
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| 68 | if(*p2!=0) *p2++=0; |
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| 69 | ch=atoi(p1); p1=find_word_start(p2); |
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| 70 | if(ch!=2 && ch!=3 && ch!=5 && ch!=7) errorquit("bad_characteristics"); |
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| 71 | p2=find_word_end(p1); if(*p2!=0) *p2++=0; |
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| 72 | p2=find_word_start(p2); *find_word_end(p2)=0; |
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| 73 | degree=strlen(p1); |
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| 74 | if(degree!=strlen(p2)) errorquit("unequal_degrees"); |
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| 75 | if(degree>MAX_DEGREE) errorquit("degree_too_high"); |
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| 76 | dt=pow(ch,degree); |
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| 77 | if(dt>=(double) MAX_LENGTH) errorquit("length_overflow"); |
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| 78 | length=dt-1-degree; |
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| 79 | for(i=0;i<degree;i++) { |
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| 7676 | bpr | 80 | c1=*(p1+i); c2=*(p2+i); |
| 81 | if(!isdigit(c1) || c1>=ch+'0') errorquit("bad_polynomial"); |
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| 82 | if(!isdigit(c2) || c2>=ch+'0') errorquit("bad_chain"); |
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| 83 | poly[i]=ch-(c1-'0'); chain[i]=c2-'0'; |
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| 10 | reyssat | 84 | } |
| 85 | for(i=0;i<length;i++) { |
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| 7676 | bpr | 86 | for(j=k=0;j<degree;k+=poly[j]*chain[j],j++); |
| 87 | k%=ch; printf("%d",k); |
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| 88 | memmove(chain,chain+1,degree-1); chain[degree-1]=k; |
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| 10 | reyssat | 89 | } |
| 90 | return 0; |
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| 91 | } |