akr	2013-07-23 01:36:36 +0900 (Tue, 23 Jul 2013)

  New Revision: 42119

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=42119

  Log:
    * bignum.c (bigdivrem_mulsub): Extracted from bigdivrem1.
      (bigdivrem1): Use bary_add.

  Modified files:
    trunk/ChangeLog
    trunk/bignum.c

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 42118)
+++ ChangeLog	(revision 42119)
@@ -1,3 +1,8 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Tue Jul 23 01:34:45 2013  Tanaka Akira  <akr@f...>
+
+	* bignum.c (bigdivrem_mulsub): Extracted from bigdivrem1.
+	  (bigdivrem1): Use bary_add.
+
 Mon Jul 22 18:39:52 2013  Masaki Matsushita  <glass.saga@g...>
 
 	* string.c (rb_str_enumerate_chars): specify array capa
Index: bignum.c
===================================================================
--- bignum.c	(revision 42118)
+++ bignum.c	(revision 42119)
@@ -5100,14 +5100,40 @@ struct big_div_struct { https://github.com/ruby/ruby/blob/trunk/bignum.c#L5100
     volatile VALUE stop;
 };
 
+static BDIGIT_DBL_SIGNED
+bigdivrem_mulsub(BDIGIT *zds, size_t zn, BDIGIT x, BDIGIT *yds, size_t yn)
+{
+    size_t i;
+    BDIGIT_DBL t2;
+    BDIGIT_DBL_SIGNED num;
+
+    assert(zn == yn + 1);
+
+    num = 0;
+    t2 = 0;
+    i = 0;
+
+    do {
+        BDIGIT_DBL ee;
+        t2 += (BDIGIT_DBL)yds[i] * x;
+        ee = num - BIGLO(t2);
+        num = (BDIGIT_DBL)zds[i] + ee;
+        if (ee) zds[i] = BIGLO(num);
+        num = BIGDN(num);
+        t2 = BIGDN(t2);
+    } while (++i < yn);
+    num += zds[i] - t2; /* borrow from high digit; don't update */
+    return num;
+}
+
 static void *
 bigdivrem1(void *ptr)
 {
     struct big_div_struct *bds = (struct big_div_struct*)ptr;
     long ny = bds->ny;
-    long i, j;
+    long j;
+    long nyzero = bds->nyzero;
     BDIGIT *yds = bds->yds, *zds = bds->zds;
-    BDIGIT_DBL t2;
     BDIGIT_DBL_SIGNED num;
     BDIGIT q;
 
@@ -5120,26 +5146,15 @@ bigdivrem1(void *ptr) https://github.com/ruby/ruby/blob/trunk/bignum.c#L5146
 	if (zds[j] == yds[ny-1]) q = BDIGMAX;
 	else q = (BDIGIT)((BIGUP(zds[j]) + zds[j-1])/yds[ny-1]);
 	if (q) {
-            i = bds->nyzero; num = 0; t2 = 0;
-	    do {			/* multiply and subtract */
-		BDIGIT_DBL ee;
-		t2 += (BDIGIT_DBL)yds[i] * q;
-		ee = num - BIGLO(t2);
-		num = (BDIGIT_DBL)zds[j - ny + i] + ee;
-		if (ee) zds[j - ny + i] = BIGLO(num);
-		num = BIGDN(num);
-		t2 = BIGDN(t2);
-	    } while (++i < ny);
-	    num += zds[j - ny + i] - t2;/* borrow from high digit; don't update */
-	    while (num) {		/* "add back" required */
-		i = 0; num = 0; q--;
-		do {
-		    BDIGIT_DBL ee = num + yds[i];
-		    num = (BDIGIT_DBL)zds[j - ny + i] + ee;
-		    if (ee) zds[j - ny + i] = BIGLO(num);
-		    num = BIGDN(num);
-		} while (++i < ny);
-		num--;
+            num = bigdivrem_mulsub(zds+j-(ny-nyzero), ny-nyzero+1,
+                                   q,
+                                   yds+nyzero, ny-nyzero);
+	    while (num) { /* "add back" required */
+		q--;
+                num = bary_add(zds+j-(ny-nyzero), ny-nyzero,
+                               zds+j-(ny-nyzero), ny-nyzero,
+                               yds+nyzero, ny-nyzero);
+                num--;
 	    }
 	}
 	zds[j] = q;

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