* bignum.c (rb_big_pow): truncate all zero BDIGITs. [ruby-dev:30733]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12224 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 34 insertions, 20 deletions

diff --git a/bignum.c b/bignum.c
index ba107e9edc..8346433a56 100644
--- a/bignum.c
+++ b/bignum.c
@@ -90,34 +90,48 @@ rb_big_2comp(VALUE x)			/* get 2's complement */
 }
 
 static VALUE
-bignorm(VALUE x)
+bigtrunc(VALUE x)
 {
-    if (FIXNUM_P(x)) {
-	return x;
-    }
-    else if (TYPE(x) == T_BIGNUM) {
-	long len = RBIGNUM(x)->len;
-	BDIGIT *ds = BDIGITS(x);
+    long len = RBIGNUM(x)->len;
+    BDIGIT *ds = BDIGITS(x);
 
-	while (len-- && !ds[len]) ;
-	RBIGNUM(x)->len = ++len;
+    while (len-- && !ds[len]);
+    RBIGNUM(x)->len = ++len;
+    return x;
+}
+
+static VALUE
+bigfixize(VALUE x)
+{
+    long len = RBIGNUM(x)->len;
+    BDIGIT *ds = BDIGITS(x);
 
-	if (len*SIZEOF_BDIGITS <= sizeof(VALUE)) {
-	    SIGNED_VALUE num = 0;
-	    while (len--) {
-		num = BIGUP(num) + ds[len];
+    if (len*SIZEOF_BDIGITS <= sizeof(VALUE)) {
+	SIGNED_VALUE num = 0;
+	while (len--) {
+	    num = BIGUP(num) + ds[len];
+	}
+	if (num >= 0) {
+	    if (RBIGNUM(x)->sign) {
+		if (POSFIXABLE(num)) return LONG2FIX(num);
 	    }
-	    if (num >= 0) {
-		if (RBIGNUM(x)->sign) {
-		    if (POSFIXABLE(num)) return LONG2FIX(num);
-		}
-		else if (NEGFIXABLE(-(long)num)) return LONG2FIX(-(long)num);
+	    else {
+		if (NEGFIXABLE(-(long)num)) return LONG2FIX(-(long)num);
 	    }
 	}
     }
     return x;
 }
 
+static VALUE
+bignorm(VALUE x)
+{
+    if (!FIXNUM_P(x) && TYPE(x) == T_BIGNUM) {
+	x = bigfixize(bigtrunc(x));
+    }
+    return x;
+}
+
 VALUE
 rb_big_norm(VALUE x)
 {
@@ -1563,10 +1577,10 @@ rb_big_pow(VALUE x, VALUE y)
 		do {
 		    yy /= 2;
 		    x = rb_big_mul0(x, x);
-		    if (!BDIGITS(x)[RBIGNUM(x)->len-1]) RBIGNUM(x)->len--;
+		    bigtrunc(x);
 		} while (yy % 2 == 0);
 		z = z ? rb_big_mul0(z, x) : x;
-		if (!BDIGITS(z)[RBIGNUM(z)->len-1]) RBIGNUM(z)->len--;
+		bigtrunc(z);
 	    }
 	    return bignorm(z);
 	}