master 8518b14: Tweak GMP usage for (HI LO US PS) timestamps

[Paul Eggert]

branch: master
commit 8518b14a76ba7531a71df97994fe8a197a429d4a
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>

    Tweak GMP usage for (HI LO US PS) timestamps
    
    * src/timefns.c (decode_time_components): Cut down on the number
    of calls to GMP functions when generating old-style (HI LO US PS)
    timestamps.
---
 src/timefns.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/timefns.c b/src/timefns.c
index 46f9193..b301c58 100644
--- a/src/timefns.c
+++ b/src/timefns.c
@@ -739,9 +739,10 @@ decode_time_components (enum timeform form,
   /* Normalize out-of-range lower-order components by carrying
      each overflow into the next higher-order component.  */
   us += ps / 1000000 - (ps % 1000000 < 0);
-  mpz_set_intmax (mpz[0], us / 1000000 - (us % 1000000 < 0));
-  mpz_add (mpz[0], mpz[0], *bignum_integer (&mpz[1], low));
-  mpz_addmul_ui (mpz[0], *bignum_integer (&mpz[1], high), 1 << LO_TIME_BITS);
+  mpz_t *s = &mpz[1];
+  mpz_set_intmax (*s, us / 1000000 - (us % 1000000 < 0));
+  mpz_add (*s, *s, *bignum_integer (&mpz[0], low));
+  mpz_addmul_ui (*s, *bignum_integer (&mpz[0], high), 1 << LO_TIME_BITS);
   ps = ps % 1000000 + 1000000 * (ps % 1000000 < 0);
   us = us % 1000000 + 1000000 * (us % 1000000 < 0);
 
@@ -751,21 +752,29 @@ decode_time_components (enum timeform form,
        {
        case TIMEFORM_HI_LO:
          /* Floats and nil were handled above, so it was an integer.  */
+         mpz_swap (mpz[0], *s);
          result->hz = make_fixnum (1);
          break;
 
        case TIMEFORM_HI_LO_US:
-         mpz_mul_ui (mpz[0], mpz[0], 1000000);
-         mpz_add_ui (mpz[0], mpz[0], us);
+         mpz_set_ui (mpz[0], us);
+         mpz_addmul_ui (mpz[0], *s, 1000000);
          result->hz = make_fixnum (1000000);
          break;
 
        case TIMEFORM_HI_LO_US_PS:
-         mpz_mul_ui (mpz[0], mpz[0], 1000000);
-         mpz_add_ui (mpz[0], mpz[0], us);
-         mpz_mul_ui (mpz[0], mpz[0], 1000000);
-         mpz_add_ui (mpz[0], mpz[0], ps);
-         result->hz = trillion;
+         {
+           #if FASTER_TIMEFNS && TRILLION <= ULONG_MAX
+             unsigned long i = us;
+             mpz_set_ui (mpz[0], i * 1000000 + ps);
+             mpz_addmul_ui (mpz[0], *s, TRILLION);
+           #else
+             intmax_t i = us;
+             mpz_set_intmax (mpz[0], i * 1000000 + ps);
+             mpz_addmul (mpz[0], *s, ztrillion);
+           #endif
+           result->hz = trillion;
+         }
          break;
 
        default:
@@ -774,7 +783,7 @@ decode_time_components (enum timeform form,
       result->ticks = make_integer_mpz ();
     }
   else
-    *dresult = mpz_get_d (mpz[0]) + (us * 1e6L + ps) / 1e12L;
+    *dresult = mpz_get_d (*s) + (us * 1e6L + ps) / 1e12L;
 
   return 0;
 }