From: Andy Polyakov <appro@openssl.org>
Date: Thu, 4 Apr 2013 13:54:08 +0000 (+0200)
Subject: dest4-sparcv9.pl: add clarification comment.
X-Git-Tag: master-post-reformat~1358
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=7f97d57236c8407a163a4e9f43a65c0dd691a057

dest4-sparcv9.pl: add clarification comment.
---

diff --git a/crypto/des/asm/dest4-sparcv9.pl b/crypto/des/asm/dest4-sparcv9.pl
index 5936a658e5..f9d9711811 100644
--- a/crypto/des/asm/dest4-sparcv9.pl
+++ b/crypto/des/asm/dest4-sparcv9.pl
@@ -282,7 +282,15 @@ des_t4_cbc_decrypt:
 	st		%f3, [$ivec + 4]
 .type	des_t4_cbc_decrypt,#function
 .size	des_t4_cbc_decrypt,.-des_t4_cbc_decrypt
+___
+
+# One might wonder why does one have back-to-back des_iip/des_ip
+# pairs between EDE passes. Indeed, aren't they inverse of each other?
+# They almost are. Outcome of the pair is 32-bit words being swapped
+# in target register. Consider pair of des_iip/des_ip as a way to
+# perform the due swap, it's actually fastest way in this case.
 
+$code.=<<___;
 .globl	des_t4_ede3_cbc_encrypt
 .align	32
 des_t4_ede3_cbc_encrypt: