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mruby-bigint (mul_karatsuba): avoid copying operand u and v

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This commit is contained in:
Yukihiro "Matz" Matsumoto
2024-09-29 23:32:44 +09:00
parent 0023cbdb3d
commit fcc1832efc
1 changed files with 5 additions and 13 deletions
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mrbgems/mruby-bigint/core/bigint.c
+5 -13
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@@ -401,19 +401,13 @@ mul_karatsuba(mrb_state *mrb, mpz_t *ww, mpz_t *u, mpz_t *v, int depth)
/* Split u, v into low/high */
mpz_t u0, u1, v0, v1;
mpz_init(mrb, &u0); mpz_init(mrb, &u1);
mpz_init(mrb, &v0); mpz_init(mrb, &v1);
u0.sn = u1.sn = v0.sn = v1.sn = 1;
mpz_realloc(mrb, &u0, n);
mpz_realloc(mrb, &u1, u->sz - n);
mpz_realloc(mrb, &v0, n);
mpz_realloc(mrb, &v1, v->sz - n);
memcpy(u0.p, u->p, n * sizeof(mp_limb));
memcpy(u1.p, u->p + n, (u->sz - n) * sizeof(mp_limb));
memcpy(v0.p, v->p, n * sizeof(mp_limb));
memcpy(v1.p, v->p + n, (v->sz - n) * sizeof(mp_limb));
/* u/v share memory with low/high mpz */
u0.sz = n; u0.p = u->p;
u1.sz = u->sz - n; u1.p = u->p + n;
v0.sz = n; v0.p = v->p;
v1.sz = v->sz - n; v1.p = v->p + n;
/* u1*v1 (high part) */
mpz_t z2;
@@ -444,8 +438,6 @@ mul_karatsuba(mrb_state *mrb, mpz_t *ww, mpz_t *u, mpz_t *v, int depth)
mpz_add(mrb, ww, ww, &z0);
// Clean-Up Memory
mpz_clear(mrb, &u0); mpz_clear(mrb, &u1);
mpz_clear(mrb, &v0); mpz_clear(mrb, &v1);
mpz_clear(mrb, &z0); mpz_clear(mrb, &z1); mpz_clear(mrb, &z2);
mpz_clear(mrb, &u0u1); mpz_clear(mrb, &v0v1);
}