From 422219fed26561363afee2639182854fe2021415 Mon Sep 17 00:00:00 2001
From: Mamone Tarsha <maamoun.tk@googlemail.com>
Date: Thu, 22 Jul 2021 13:07:24 +0300
Subject: [PATCH] [S390x] Optimize memxor

---
 s390x/machine.m4 | 17 ++++++++++++++++
 s390x/memxor.asm | 52 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 s390x/memxor.asm

diff --git a/s390x/machine.m4 b/s390x/machine.m4
index 8626cec1..fe49425c 100644
--- a/s390x/machine.m4
+++ b/s390x/machine.m4
@@ -19,3 +19,20 @@ C Free allocated stack space
 C FREE_STACK(SPACE_LEN)
 define(`FREE_STACK',
 `aghi           SP,STANDARD_STACK_FRAME+$1')
+
+C XOR contents of two areas in storage with specific length
+C DST: The destination area of storage
+C SRC: The source area of storage
+C LEN: The length of storage area. LEN <= 256
+C TMP_ADDR: A temporary register that handles the XOR instrcution address
+C All parameters are general registers and cannot be assigned to
+C general register 0
+C XOR_LEN(DST, SRC, LEN, TMP_ADDR)
+define(`XOR_LEN',
+`larl           $4,18f
+    aghi           $3,-1
+    jm             19f
+    ex             $3,0($4)
+    j              19f
+18: xc             0(1,$1),0($2)
+19:')
diff --git a/s390x/memxor.asm b/s390x/memxor.asm
new file mode 100644
index 00000000..699fda49
--- /dev/null
+++ b/s390x/memxor.asm
@@ -0,0 +1,52 @@
+C s390x/memxor.asm
+
+ifelse(`
+   Copyright (C) 2021 Mamone Tarsha
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+')
+
+.file "memxor.asm"
+
+.text
+
+C void * memxor(void *dst, const void *src, size_t n)      
+
+PROLOGUE(nettle_memxor)
+    srlg           %r5,%r4,8
+    clgije         %r5,0,Llen
+L256_loop:
+    xc             0(256,%r2),0(%r3)
+    aghi           %r2,256
+    aghi           %r3,256
+    brctg          %r5,L256_loop
+Llen:
+    risbg          %r5,%r4,56,191,0
+    jz             Ldone
+    XOR_LEN(%r2,%r3,%r5,%r1)
+Ldone:
+    br             RA
+EPILOGUE(nettle_memxor)
-- 
2.47.2