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80 lines
1.4 KiB
C
80 lines
1.4 KiB
C
/* j/3/rub.c
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**
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*/
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#include "all.h"
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/* functions
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*/
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u3_noun
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u3qe_rub(u3_atom a,
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u3_atom b)
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{
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u3_atom c, d, e;
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u3_atom w, x, y, z;
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u3_atom p, q;
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u3_atom m = u3qa_add(a, u3r_met(0, b));
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// Compute c and d.
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{
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x = u3k(a);
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while ( 0 == u3qc_cut(0, x, 1, b) ) {
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u3_atom y = u3qa_inc(x);
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// Sanity check: crash if decoding more bits than available
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if ( c3y == u3qa_gth(x, m)) {
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// fprintf(stderr, "[%%rub-hard %d %d %d]\r\n", a, x, m);
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return u3m_bail(c3__exit);
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}
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u3z(x);
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x = y;
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}
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if ( c3y == u3r_sing(x, a) ) {
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u3z(x);
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return u3nc(1, 0);
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}
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c = u3qa_sub(x, a);
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d = u3qa_inc(x);
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u3z(x);
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}
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// Compute e, p, q.
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{
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x = u3qa_dec(c);
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y = u3qc_bex(x);
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z = u3qc_cut(0, d, x, b);
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e = u3qa_add(y, z);
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u3z(y); u3z(z);
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w = u3qa_add(c, c);
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y = u3qa_add(w, e);
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z = u3qa_add(d, x);
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p = u3qa_add(w, e);
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q = u3qc_cut(0, z, e, b);
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u3z(w); u3z(x); u3z(y); u3z(z);
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return u3nc(p, q);
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}
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}
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u3_noun
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u3we_rub(u3_noun cor)
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{
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u3_noun a, b;
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if ( (c3n == u3r_mean(cor, u3x_sam_2, &a, u3x_sam_3, &b, 0)) ||
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(c3n == u3ud(a)) ||
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(c3n == u3ud(b)) )
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{
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return u3m_bail(c3__fail);
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} else {
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return u3qe_rub(a, b);
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}
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}
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