admin/mruby-mruby
1
0
Fork 0
mirror of https://github.com/mruby/mruby synced 2026-06-08 16:11:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

mruby-bigint (mul_karatsuba) improve performance

Browse Source 
Unnecessary mpz_t u0u1 and v0v1 are removed.
This commit is contained in:
Yukihiro "Matz" Matsumoto
2024-10-05 10:57:42 +09:00
parent 8faf78f1b8
commit be9da7199b
1 changed files with 22 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mrbgems/mruby-bigint/core/bigint.c
+22 -27
View File
@@ -399,35 +399,28 @@ mul_karatsuba(mrb_state *mrb, mpz_t *ww, mpz_t *u, mpz_t *v, int depth)
size_t n = (u->sz > v->sz ? v->sz : u->sz) / 2;
/* Split u, v into low/high */
mpz_t u0, u1, v0, v1;
u0.sn = u1.sn = v0.sn = v1.sn = 1;
u0.sn = 1; u0.sz = n; u0.p = u->p; // u0 references the lower half of u
u1.sn = 1; u1.sz = u->sz - n; u1.p = u->p + n; // u1 references the upper half of u
v0.sn = 1; v0.sz = n; v0.p = v->p; // v0 references the lower half of v
v1.sn = 1; v1.sz = v->sz - n; v1.p = v->p + n; // v1 references the upper half of v
/* 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;
mpz_t z0, z1, z2;
mpz_init(mrb, &z0); // z0 = u0 * v0 (lower part)
mpz_init(mrb, &z1); // z1 = (u0 + u1) * (v0 + v1) (intermediate result)
mpz_init(mrb, &z2); // z2 = u1 * v1 (upper part)
/* u1*v1 (high part) */
mpz_t z2;
mpz_init(mrb, &z2);
mul_karatsuba(mrb, &z2, &u1, &v1, depth + 1);
// Calculate (u0 + u1) and (v0 + v1) using z1 and z2 temporarily
mpz_add(mrb, &z1, &u0, &u1); // temp = u0 + u1
mpz_add(mrb, &z2, &v0, &v1); // z2 = v0 + v1
/* u0*v0 (low part) */
mpz_t z0;
mpz_init(mrb, &z0);
mul_karatsuba(mrb, &z0, &u0, &v0, depth + 1);
mul_karatsuba(mrb, &z1, &z1, &z2, depth + 1); // Calculate (u0 + u1) * (v0 + v1) and store in z1
mul_karatsuba(mrb, &z2, &u1, &v1, depth + 1); // Calculate high product (u1 * v1)
mul_karatsuba(mrb, &z0, &u0, &v0, depth + 1); // Calculate low product (u0 * v0)
/* (u1+u0)*(v1+v0) */
mpz_t u0u1, v0v1, z1;
mpz_init(mrb, &u0u1); mpz_init(mrb, &v0v1); mpz_init(mrb, &z1);
mpz_add(mrb, &u0u1, &u0, &u1);
mpz_add(mrb, &v0v1, &v0, &v1);
mul_karatsuba(mrb, &z1, &u0u1, &v0v1, depth + 1);
mpz_sub(mrb, &z1, &z1, &z0);
mpz_sub(mrb, &z1, &z1, &z2);
// Calculate z1 = z1 - z0 - z2 for intermediate calculations
mpz_sub(mrb, &z1, &z1, &z0); // z1 -= z0
mpz_sub(mrb, &z1, &z1, &z2); // z1 -= u1*v1 (z2 currently holds u1*v1)
/* Bitshift z1/z2 */
mpz_mul_2exp(mrb, &z2, &z2, 2 * n * sizeof(mp_limb) * 8);
@@ -436,10 +429,12 @@ mul_karatsuba(mrb_state *mrb, mpz_t *ww, mpz_t *u, mpz_t *v, int depth)
/* Combine the result*/
mpz_add(mrb, ww, &z2, &z1);
mpz_add(mrb, ww, ww, &z0);
trim(ww);
// Clean-Up Memory
mpz_clear(mrb, &z0); mpz_clear(mrb, &z1); mpz_clear(mrb, &z2);
mpz_clear(mrb, &u0u1); mpz_clear(mrb, &v0v1);
// Free memory allocated for z0, z1, z2, and temp
mpz_clear(mrb, &z0);
mpz_clear(mrb, &z1);
mpz_clear(mrb, &z2);
}
// Multiplication Entry Point */