diff options
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | bignum.c | 19 |
2 files changed, 23 insertions, 1 deletions
@@ -1,3 +1,8 @@ +Tue Jul 23 20:14:55 2013 Tanaka Akira <akr@fsij.org> + + * bignum.c (bary_divmod): Add special cases for x < y easily detected + and nx == 2 && ny == 2. + Tue Jul 23 19:48:38 2013 Koichi Sasada <ko1@atdot.net> * thread_(pthread|win32).h: rename rb_thread_cond_t to @@ -5266,12 +5266,29 @@ bary_divmod(BDIGIT *qds, size_t nq, BDIGIT *rds, size_t nr, BDIGIT *xds, size_t return; } - if (ny == 1) { + if (nx < ny || (nx == ny && xds[nx - 1] < yds[ny - 1])) { + MEMCPY(rds, xds, BDIGIT, nx); + BDIGITS_ZERO(rds+nx, nr-nx); + BDIGITS_ZERO(qds, nq); + } + else if (ny == 1) { MEMCPY(qds, xds, BDIGIT, nx); BDIGITS_ZERO(qds+nx, nq-nx); rds[0] = bigdivrem_single(qds, xds, nx, yds[0]); BDIGITS_ZERO(rds+1, nr-1); } + else if (nx == 2 && ny == 2) { + BDIGIT_DBL x = xds[0] | BIGUP(xds[1]); + BDIGIT_DBL y = yds[0] | BIGUP(yds[1]); + BDIGIT_DBL q = x / y; + BDIGIT_DBL r = x % y; + qds[0] = BIGLO(q); + qds[1] = BIGLO(BIGDN(q)); + BDIGITS_ZERO(qds+2, nq-2); + rds[0] = BIGLO(r); + rds[1] = BIGLO(BIGDN(r)); + BDIGITS_ZERO(rds+2, nr-2); + } else { int extra_words; long j; |