Provide many gcd_11.

1 files changed, 79 insertions, 0 deletions

diff --git a/mpn/alpha/ev67/gcd_11.asm b/mpn/alpha/ev67/gcd_11.asm
new file mode 100644
index 000000000..536f55357
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+++ b/mpn/alpha/ev67/gcd_11.asm
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+dnl  Alpha ev67 mpn_gcd_1 -- Nx1 greatest common divisor.
+
+dnl  Copyright 2003, 2004 Free Software Foundation, Inc.
+
+dnl  This file is part of the GNU MP Library.
+dnl
+dnl  The GNU MP Library is free software; you can redistribute it and/or modify
+dnl  it under the terms of either:
+dnl
+dnl    * the GNU Lesser General Public License as published by the Free
+dnl      Software Foundation; either version 3 of the License, or (at your
+dnl      option) any later version.
+dnl
+dnl  or
+dnl
+dnl    * the GNU General Public License as published by the Free Software
+dnl      Foundation; either version 2 of the License, or (at your option) any
+dnl      later version.
+dnl
+dnl  or both in parallel, as here.
+dnl
+dnl  The GNU MP Library is distributed in the hope that it will be useful, but
+dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+dnl  for more details.
+dnl
+dnl  You should have received copies of the GNU General Public License and the
+dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
+dnl  see https://www.gnu.org/licenses/.
+
+include(`../config.m4')
+
+
+C ev67: 3.4 cycles/bitpair for 1x1 part
+
+
+C mp_limb_t mpn_gcd_1 (mp_srcptr xp, mp_size_t xsize, mp_limb_t y);
+C
+C In the 1x1 part, the algorithm is to change x,y to abs(x-y),min(x,y) and
+C strip trailing zeros from abs(x-y) to maintain x and y both odd.
+C
+C The trailing zeros are calculated from just x-y, since in twos-complement
+C there's the same number of trailing zeros on d or -d.  This means the cttz
+C runs in parallel with abs(x-y).
+C
+C The loop takes 5 cycles, and at 0.68 iterations per bit for two N-bit
+C operands with this algorithm gives the measured 3.4 c/l.
+C
+C The slottings shown are for SVR4 style systems, Unicos differs in the
+C initial gp setup and the LEA.
+
+
+ASM_START()
+PROLOGUE(mpn_gcd_11)
+	mov	r16, r0
+	mov	r17, r1
+
+	ALIGN(16)
+L(top):	subq	r0, r1, r7		C l0  d = x - y
+	cmpult	r0, r1, r16		C u0  test x >= y
+
+	subq	r1, r0, r4		C l0  new_x = y - x
+	cttz	r7, r8			C U0  d twos
+
+	cmoveq	r16, r7, r4		C l0  new_x = d if x>=y
+	cmovne	r16, r0, r1		C u0  y = x if x<y
+	unop				C l   \ force cmoveq into l0
+	unop				C u   /
+
+	C				C cmoveq2 L0, cmovne2 U0
+
+	srl	r4, r8, r0		C U0  x = new_x >> twos
+	bne	r7, L(top)		C U1  stop when d==0
+
+
+L(end):	mov	r1, r0			C U0  return y << common_twos
+	ret	r31, (r26), 1		C L0
+EPILOGUE()
+ASM_END()