ref: 42c7c41a0e836e244d1b1fb14c395968da6c01f8
dir: /libmp/mpmodop.c/
#include "os.h" #include <mp.h> /* operands need to have m->top+1 digits of space and satisfy 0 ≤ a ≤ m-1 */ static mpint* modarg(mpint *a, mpint *m) { if(a->size <= m->top || a->sign < 0 || mpmagcmp(a, m) >= 0){ a = mpcopy(a); mpmod(a, m, a); mpbits(a, Dbits*(m->top+1)); a->top = m->top; } else if(a->top < m->top){ memset(&a->p[a->top], 0, (m->top - a->top)*Dbytes); } return a; } void mpmodadd(mpint *b1, mpint *b2, mpint *m, mpint *sum) { mpint *a, *b; mpdigit d; int i, j; a = modarg(b1, m); b = modarg(b2, m); sum->flags |= (a->flags | b->flags) & MPtimesafe; mpbits(sum, Dbits*2*(m->top+1)); mpvecadd(a->p, m->top, b->p, m->top, sum->p); mpvecsub(sum->p, m->top+1, m->p, m->top, sum->p+m->top+1); d = sum->p[2*m->top+1]; for(i = 0, j = m->top+1; i < m->top; i++, j++) sum->p[i] = (sum->p[i] & d) | (sum->p[j] & ~d); sum->top = m->top; sum->sign = 1; mpnorm(sum); if(a != b1) mpfree(a); if(b != b2) mpfree(b); } void mpmodsub(mpint *b1, mpint *b2, mpint *m, mpint *diff) { mpint *a, *b; mpdigit d; int i, j; a = modarg(b1, m); b = modarg(b2, m); diff->flags |= (a->flags | b->flags) & MPtimesafe; mpbits(diff, Dbits*2*(m->top+1)); a->p[m->top] = 0; mpvecsub(a->p, m->top+1, b->p, m->top, diff->p); mpvecadd(diff->p, m->top, m->p, m->top, diff->p+m->top+1); d = ~diff->p[m->top]; for(i = 0, j = m->top+1; i < m->top; i++, j++) diff->p[i] = (diff->p[i] & d) | (diff->p[j] & ~d); diff->top = m->top; diff->sign = 1; mpnorm(diff); if(a != b1) mpfree(a); if(b != b2) mpfree(b); } void mpmodmul(mpint *b1, mpint *b2, mpint *m, mpint *prod) { mpint *a, *b; a = modarg(b1, m); b = modarg(b2, m); mpmul(a, b, prod); mpmod(prod, m, prod); if(a != b1) mpfree(a); if(b != b2) mpfree(b); }