From ce84456ddf4e57c18a84858755b8b90c183a270e Mon Sep 17 00:00:00 2001
From: Richard Levitte
Date: Sat, 26 Mar 2016 00:07:50 +0100
Subject: [PATCH] Math::BigInt does floored divs, BN_div does truncated div,
compensate
According to documentation, perl's Math::BigInt does floored division,
i.e. the bdiv function does 1 / -4 = -1. OpenSSL's BN_div, as well as
bc, do truncated division, i.e. 1 / -4 = 0.
We need to compensate for that difference in test/recipes/bc.pl to
make sure to verify the bntest results under its own conditions, by
dividing the absolute values of the given numbers and fixup the
result's negativity afterwards.
Closes RT#4485
Reviewed-by: Viktor Dukhovni
---
test/recipes/bc.pl | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/test/recipes/bc.pl b/test/recipes/bc.pl
index 29a4a8a84a..f7d4dc681d 100644
--- a/test/recipes/bc.pl
+++ b/test/recipes/bc.pl
@@ -46,7 +46,16 @@ sub __multiplier {
if ($operator eq "*") {
$operand1->bmul($operand2);
} elsif ($operator eq "/") {
+ # Math::BigInt->bdiv() is documented to do floored division,
+ # i.e. 1 / -4 = -1, while bc and OpenSSL BN_div do truncated
+ # division, i.e. 1 / -4 = 0. We need to make the operation
+ # work like OpenSSL's BN_div to be able to verify.
+ my $neg = ($operand1->is_neg()
+ ? !$operand2->is_neg() : $operand2->is_neg());
+ $operand1->babs();
+ $operand2->babs();
$operand1->bdiv($operand2);
+ if ($neg) { $operand1->bneg(); }
} elsif ($operator eq "%") {
# Here's a bit of a quirk...
# With OpenSSL's BN, as well as bc, the result of -10 % 3 is -1
--
2.17.1