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 */
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 */
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 /* This program generates cyclic code from a polynomial
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 /* This program generates cyclic code from a polynomial
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  * defined over a prime field.
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  * defined over a prime field.
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  * It does not check whether the polynomial is primitive or irreducible.
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  * It does not check whether the polynomial is primitive or irreducible.
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  * Accepted parameter: 3 words.
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  * Accepted parameter: 3 words.
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  * Word 1: field characteristics, limited to 2,3,5,7.
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  * Word 1: field characteristics, limited to 2,3,5,7.
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  * Word 2: The polynomial coefficients (except the leading one, from
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  * Word 2: The polynomial coefficients (except the leading one, from
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                                         lower degree to higher)
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     lower degree to higher)
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  * Word 3: The starting status (starting from the first bit).
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  * Word 3: The starting status (starting from the first bit).
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  */
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  */
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#include "../wims.h"
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#include "../wims.h"
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void errorquit(char *msg)
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void errorquit(char *msg)
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{
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{
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    fprintf(stderr,"%s\n",msg); exit(1);
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    fprintf(stderr,"%s\n",msg); exit(1);
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}
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}
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        /* Points to the end of the word */
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/* Points to the end of the word */
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char *find_word_end(char *p)
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char *find_word_end(char *p)
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{
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{
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    int i;
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    int i;
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    for(i=0;!isspace(*p) && *p!=0 && i<MAX_LINELEN; p++,i++);
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    for(i=0;!isspace(*p) && *p!=0 && i<MAX_LINELEN; p++,i++);
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    return p;
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    return p;
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}
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}
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        /* Strips leading spaces */
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/* Strips leading spaces */
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char *find_word_start(char *p)
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char *find_word_start(char *p)
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{
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{
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    int i;
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    int i;
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    for(i=0; isspace(*p) && i<MAX_LINELEN; p++,i++);
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    for(i=0; isspace(*p) && i<MAX_LINELEN; p++,i++);
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    return p;
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    return p;
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{
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{
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    char *parm, *p1, *p2, c1, c2;
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    char *parm, *p1, *p2, c1, c2;
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    char pbuf[1024];
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    char pbuf[1024];
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    int i,j,k;
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    int i,j,k;
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    double dt;
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    double dt;
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    parm=getenv("wims_exec_parm");
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    parm=getenv("wims_exec_parm");
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    if(parm==NULL || *parm==0) errorquit("no_parameter");
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    if(parm==NULL || *parm==0) errorquit("no_parameter");
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    snprintf(pbuf,sizeof(pbuf),"%s",parm);
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    snprintf(pbuf,sizeof(pbuf),"%s",parm);
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    p1=find_word_start(pbuf); p2=find_word_end(p1);
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    p1=find_word_start(pbuf); p2=find_word_end(p1);
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    if(*p2!=0) *p2++=0;
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    if(*p2!=0) *p2++=0;
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    if(degree>MAX_DEGREE) errorquit("degree_too_high");
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    if(degree>MAX_DEGREE) errorquit("degree_too_high");
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    dt=pow(ch,degree);
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    dt=pow(ch,degree);
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    if(dt>=(double) MAX_LENGTH) errorquit("length_overflow");
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    if(dt>=(double) MAX_LENGTH) errorquit("length_overflow");
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    length=dt-1-degree;
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    length=dt-1-degree;
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    for(i=0;i<degree;i++) {
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    for(i=0;i<degree;i++) {
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        c1=*(p1+i); c2=*(p2+i);
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      c1=*(p1+i); c2=*(p2+i);
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        if(!isdigit(c1) || c1>=ch+'0') errorquit("bad_polynomial");
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      if(!isdigit(c1) || c1>=ch+'0') errorquit("bad_polynomial");
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        if(!isdigit(c2) || c2>=ch+'0') errorquit("bad_chain");
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      if(!isdigit(c2) || c2>=ch+'0') errorquit("bad_chain");
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        poly[i]=ch-(c1-'0'); chain[i]=c2-'0';
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      poly[i]=ch-(c1-'0'); chain[i]=c2-'0';
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    }
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    }
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    for(i=0;i<length;i++) {
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    for(i=0;i<length;i++) {
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        for(j=k=0;j<degree;k+=poly[j]*chain[j],j++);
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      for(j=k=0;j<degree;k+=poly[j]*chain[j],j++);
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        k%=ch; printf("%d",k);
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      k%=ch; printf("%d",k);
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        memmove(chain,chain+1,degree-1); chain[degree-1]=k;
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      memmove(chain,chain+1,degree-1); chain[degree-1]=k;
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    }
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    }
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    return 0;
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    return 0;
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}
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}
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