From 55c3f7b6440b3c49e39941876b9f07e913501675 Mon Sep 17 00:00:00 2001
From: shyouhei <shyouhei@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 15 Aug 2007 21:37:41 +0000
Subject: 	* bignum.c (rb_big_lshift, rb_big_rshift): separated functions
 	  to get rid of infinite recursion.  fixed calculation in edge 	 
 cases.  [ruby-dev:31244] 	* numeric.c (rb_fix_lshift, rb_fix_rshift):
 ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_5@13022 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 bignum.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 91 insertions(+), 7 deletions(-)

(limited to 'bignum.c')

diff --git a/bignum.c b/bignum.c
index 489ae77b2e..17c05c0ceb 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1509,6 +1509,20 @@ rb_big_remainder(x, y)
     return bignorm(z);
 }
 
+static VALUE big_lshift _((VALUE, unsigned int));
+static VALUE big_rshift _((VALUE, unsigned int));
+
+static VALUE big_shift(x, n)
+    VALUE x;
+    int n;
+{
+    if (n < 0)
+	return big_lshift(x, (unsigned int)n);
+    else if (n > 0)
+	return big_rshift(x, (unsigned int)n);
+    return x;
+}
+
 /*
  *  call-seq:
  *     big.divmod(numeric)   => array
@@ -1812,7 +1826,15 @@ rb_big_xor(xx, yy)
     return bignorm(z);
 }
 
-static VALUE rb_big_rshift _((VALUE,VALUE));
+static VALUE
+check_shiftdown(VALUE y, VALUE x)
+{
+    if (!RBIGNUM(x)->len) return INT2FIX(0);
+    if (RBIGNUM(y)->len > SIZEOF_LONG / SIZEOF_BDIGITS) {
+	return RBIGNUM(x)->sign ? INT2FIX(0) : INT2FIX(-1);
+    }
+    return Qnil;
+}
 
 /*
  * call-seq:
@@ -1824,16 +1846,46 @@ static VALUE rb_big_rshift _((VALUE,VALUE));
 VALUE
 rb_big_lshift(x, y)
     VALUE x, y;
+{
+    int shift, neg = 0;
+
+    for (;;) {
+	if (FIXNUM_P(y)) {
+	    shift = FIX2INT(y);
+	    if (shift < 0) {
+		neg = 1;
+		shift = -shift;
+	    }
+	    break;
+	}
+	else if (TYPE(y) == T_BIGNUM) {
+	    if (!RBIGNUM(y)->sign) {
+		VALUE t = check_shiftdown(y, x);
+		if (!NIL_P(t)) return t;
+		neg = 1;
+	    }
+	    shift = big2ulong(y, "long", Qtrue);
+	    break;
+	}
+	y = rb_to_int(y);
+    }
+
+    if (neg) return big_rshift(x, shift);
+    return big_lshift(x, shift);
+}
+
+static VALUE
+big_lshift(x, shift)
+    VALUE x;
+    unsigned int shift;
 {
     BDIGIT *xds, *zds;
-    int shift = NUM2INT(y);
     int s1 = shift/BITSPERDIG;
     int s2 = shift%BITSPERDIG;
     VALUE z;
     BDIGIT_DBL num = 0;
     long len, i;
 
-    if (shift < 0) return rb_big_rshift(x, INT2FIX(-shift));
     len = RBIGNUM(x)->len;
     z = bignew(len+s1+1, RBIGNUM(x)->sign);
     zds = BDIGITS(z);
@@ -1857,12 +1909,46 @@ rb_big_lshift(x, y)
  * Shifts big right _numeric_ positions (left if _numeric_ is negative).
  */
 
-static VALUE
+VALUE
 rb_big_rshift(x, y)
     VALUE x, y;
+{
+    int shift;
+    int neg = 0;
+
+    for (;;) {
+	if (FIXNUM_P(y)) {
+	    shift = FIX2INT(y);
+	    if (shift < 0) {
+		neg = 1;
+		shift = -shift;
+	    }
+	    break;
+	}
+	else if (TYPE(y) == T_BIGNUM) {
+	    if (RBIGNUM(y)->sign) {
+		VALUE t = check_shiftdown(y, x);
+		if (!NIL_P(t)) return t;
+	    }
+	    else {
+		neg = 1;
+	    }
+	    shift = big2ulong(y, "long", Qtrue);
+	    break;
+	}
+	y = rb_to_int(y);
+    }
+
+    if (neg) return big_lshift(x, shift);
+    return big_rshift(x, shift);
+}
+
+static VALUE
+big_rshift(x, shift)
+    VALUE x;
+    unsigned int shift;
 {
     BDIGIT *xds, *zds;
-    int shift = NUM2INT(y);
     long s1 = shift/BITSPERDIG;
     long s2 = shift%BITSPERDIG;
     VALUE z;
@@ -1870,8 +1956,6 @@ rb_big_rshift(x, y)
     long i, j;
     volatile VALUE save_x;
 
-    if (shift < 0) return rb_big_lshift(x, INT2FIX(-shift));
-
     if (s1 > RBIGNUM(x)->len) {
 	if (RBIGNUM(x)->sign)
 	    return INT2FIX(0);
-- 
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