1 files changed, 120 insertions, 0 deletions
diff --git a/mpi/alpha/mpih-rshift.S b/mpi/alpha/mpih-rshift.S
new file mode 100644
index 000000000..e93315ae2
--- /dev/null
+++ b/mpi/alpha/mpih-rshift.S
@@ -0,0 +1,120 @@
+/* alpha    rshift
+ *	Copyright (C) 1994, 1995 Free Software Foundation, Inc.
+ *	Copyright (C) 1998 Free Software Foundation, Inc.
+ *
+ * This file is part of GNUPG.
+ *
+ * GNUPG is free software; you can redistribute it and/or modify
+ * it under the terms of 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.
+ *
+ * GNUPG 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 a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ *	 The GNU MP Library itself is published under the LGPL;
+ *	 however I decided to publish this code under the plain GPL.
+ */
+
+
+
+
+/*******************
+ * mpi_limb_t
+ * mpihelp_rshift( mpi_ptr_t wp,	(r16)
+ *		   mpi_ptr_t up,	(r17)
+ *		   mpi_size_t usize,	(r18)
+ *		   unsigned cnt)	(r19)
+ *
+ * This code runs at 4.8 cycles/limb on the 21064.  With infinite unrolling,
+ * it would take 4 cycles/limb.  It should be possible to get down to 3
+ * cycles/limb since both ldq and stq can be paired with the other used
+ * instructions.  But there are many restrictions in the 21064 pipeline that
+ * makes it hard, if not impossible, to get down to 3 cycles/limb:
+ *
+ * 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
+ * 2. Only aligned instruction pairs can be paired.
+ * 3. The store buffer or silo might not be able to deal with the bandwidth.
+ */
+
+	.set	noreorder
+	.set	noat
+.text
+	.align	3
+	.globl	mpihelp_rshift
+	.ent	mpihelp_rshift
+mpihelp_rshift:
+	.frame	$30,0,$26,0
+
+	ldq	$4,0($17)	# load first limb
+	addq	$17,8,$17
+	subq	$31,$19,$7
+	subq	$18,1,$18
+	and	$18,4-1,$20	# number of limbs in first loop
+	sll	$4,$7,$0	# compute function result
+
+	beq	$20,.R0
+	subq	$18,$20,$18
+
+	.align	3
+.Roop0:
+	ldq	$3,0($17)
+	addq	$16,8,$16
+	addq	$17,8,$17
+	subq	$20,1,$20
+	srl	$4,$19,$5
+	sll	$3,$7,$6
+	bis	$3,$3,$4
+	bis	$5,$6,$8
+	stq	$8,-8($16)
+	bne	$20,.Roop0
+
+.R0:	beq	$18,.Rend
+
+	.align	3
+.Roop:	ldq	$3,0($17)
+	addq	$16,32,$16
+	subq	$18,4,$18
+	srl	$4,$19,$5
+	sll	$3,$7,$6
+
+	ldq	$4,8($17)
+	srl	$3,$19,$1
+	bis	$5,$6,$8
+	stq	$8,-32($16)
+	sll	$4,$7,$2
+
+	ldq	$3,16($17)
+	srl	$4,$19,$5
+	bis	$1,$2,$8
+	stq	$8,-24($16)
+	sll	$3,$7,$6
+
+	ldq	$4,24($17)
+	srl	$3,$19,$1
+	bis	$5,$6,$8
+	stq	$8,-16($16)
+	sll	$4,$7,$2
+
+	addq	$17,32,$17
+	bis	$1,$2,$8
+	stq	$8,-8($16)
+
+	bgt	$18,.Roop
+
+.Rend:	srl	$4,$19,$8
+	stq	$8,0($16)
+	ret	$31,($26),1
+	.end	mpihelp_rshift
+