X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbigint.pl;h=bd1d91f82293343aab7f112bfcddef0cff253344;hb=a4fc7abc9c5502fa20253f620ede1e956c44caed;hp=adeb17f28a93700503b220ee53a06377e7a4b5ee;hpb=9d116dd7c895b17badf4ad422ae44da0c4df7bc2;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/bigint.pl b/lib/bigint.pl
index adeb17f..bd1d91f 100644
--- a/lib/bigint.pl
+++ b/lib/bigint.pl
@@ -1,5 +1,13 @@
 package bigint;
-
+#
+# This library is no longer being maintained, and is included for backward
+# compatibility with Perl 4 programs which may require it.
+#
+# In particular, this should not be used as an example of modern Perl
+# programming techniques.
+#
+# Suggested alternative:  Math::BigInt
+#
 # arbitrary size integer math package
 #
 # by Mark Biggar
@@ -12,7 +20,7 @@ package bigint;
 #   '+0'                            canonical zero value
 #   '   -123 123 123'               canonical value '-123123123'
 #   '1 23 456 7890'                 canonical value '+1234567890'
-# Output values always always in canonical form
+# Output values always in canonical form
 #
 # Actual math is done in an internal format consisting of an array
 #   whose first element is the sign (/^[+-]$/) and whose remaining 
@@ -34,6 +42,12 @@ package bigint;
 #   bnorm(BINT) return BINT             normalization
 #
 
+# overcome a floating point problem on certain osnames (posix-bc, os390)
+BEGIN {
+    my $x = 100000.0;
+    my $use_mult = int($x*1e-5)*1e5 == $x ? 1 : 0;
+}
+
 $zero = 0;
 
 
@@ -204,8 +218,14 @@ sub main'bmul { #(num_str, num_str) return num_str
 	    ($car, $cty) = (0, $[);
 	    for $y (@y) {
 		$prod = $x * $y + $prod[$cty] + $car;
-		$prod[$cty++] =
-		    $prod - ($car = int($prod * 1e-5)) * 1e5;
+                if ($use_mult) {
+		    $prod[$cty++] =
+		        $prod - ($car = int($prod * 1e-5)) * 1e5;
+                }
+                else {
+		    $prod[$cty++] =
+		        $prod - ($car = int($prod / 1e5)) * 1e5;
+                }
 	    }
 	    $prod[$cty] += $car if $car;
 	    $x = shift @prod;
@@ -231,12 +251,22 @@ sub main'bdiv { #(dividend: num_str, divisor: num_str) return num_str
     if (($dd = int(1e5/($y[$#y]+1))) != 1) {
 	for $x (@x) {
 	    $x = $x * $dd + $car;
+            if ($use_mult) {
 	    $x -= ($car = int($x * 1e-5)) * 1e5;
+            }
+            else {
+	    $x -= ($car = int($x / 1e5)) * 1e5;
+            }
 	}
 	push(@x, $car); $car = 0;
 	for $y (@y) {
 	    $y = $y * $dd + $car;
+            if ($use_mult) {
 	    $y -= ($car = int($y * 1e-5)) * 1e5;
+            }
+            else {
+	    $y -= ($car = int($y / 1e5)) * 1e5;
+            }
 	}
     }
     else {
@@ -251,7 +281,12 @@ sub main'bdiv { #(dividend: num_str, divisor: num_str) return num_str
 	    ($car, $bar) = (0,0);
 	    for ($y = $[, $x = $#x-$#y+$[-1; $y <= $#y; ++$y,++$x) {
 		$prd = $q * $y[$y] + $car;
+                if ($use_mult) {
 		$prd -= ($car = int($prd * 1e-5)) * 1e5;
+                }
+                else {
+		$prd -= ($car = int($prd / 1e5)) * 1e5;
+                }
 		$x[$x] += 1e5 if ($bar = (($x[$x] -= $prd + $bar) < 0));
 	    }
 	    if ($x[$#x] < $car + $bar) {