dnl  SPARC64 mpn_gcd_1.

dnl  Based on the K7 gcd_1.asm, by Kevin Ryde.  Rehacked for SPARC by Torbjörn

dnl  Granlund.

dnl  Copyright 2000-2002, 2005, 2009, 2011-2013 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		  cycles/bit (approx)

C UltraSPARC 1&2:	 5.1

C UltraSPARC 3:		 5.0

C UltraSPARC T1:	11.4

C UltraSPARC T3:	10

C UltraSPARC T4:	 6

C Numbers measured with: speed -CD -s32-64 -t32 mpn_gcd_1

C ctz_table[n] is the number of trailing zeros on n, or MAXSHIFT if n==0.

deflit(MAXSHIFT, 7)

deflit(MASK, eval((m4_lshift(1,MAXSHIFT))-1))

	RODATA

	TYPE(ctz_table,object)

ctz_table:

	.byte	MAXSHIFT

forloop(i,1,MASK,

`	.byte	m4_count_trailing_zeros(i)

')

	SIZE(ctz_table,.-ctz_table)

C Threshold of when to call bmod when U is one limb.  Should be about

C (time_in_cycles(bmod_1,1) + call_overhead) / (cycles/bit).

define(`BMOD_THRES_LOG2', 14)

C INPUT PARAMETERS

define(`up',    `%i0')

define(`n',     `%i1')

define(`v0',    `%i2')

ASM_START()

	REGISTER(%g2,#scratch)

	REGISTER(%g3,#scratch)

PROLOGUE(mpn_gcd_1)

	save	%sp, -192, %sp

	ldx	[up+0], %g1		C U low limb

	mov	-1, %i4

	or	v0, %g1, %g2		C x | y

L(twos):

	inc	%i4

	andcc	%g2, 1, %g0

	bz,a	%xcc, L(twos)

	 srlx	%g2, 1, %g2

L(divide_strip_y):

	andcc	v0, 1, %g0

	bz,a	%xcc, L(divide_strip_y)

	 srlx	v0, 1, v0

	cmp	n, 1			C if n > 1 we need

	bnz	%xcc, L(bmod)		C to call bmod_1

	 nop

C Both U and V are single limbs, reduce with bmod if u0 >> v0.

	srlx	%g1, BMOD_THRES_LOG2, %g2

	cmp	%g2, v0

	bleu	%xcc, L(noreduce)

	 mov	%g1, %o0

L(bmod):

	mov	up, %o0

	mov	n, %o1

	mov	v0, %o2

	call	mpn_modexact_1c_odd

	 mov	0, %o3

L(noreduce):

	LEA64(ctz_table, i5, g4)

	cmp	%o0, 0

	bnz	%xcc, L(mid)

	 and	%o0, MASK, %g3		C

	return	%i7+8

	 sllx	%o2, %o4, %o0		C CAUTION: v0 alias for o2

	ALIGN(16)

L(top):	movcc	%xcc, %l4, v0		C v = min(u,v)

	movcc	%xcc, %l2, %o0		C u = |v - u]

L(mid):	ldub	[%i5+%g3], %g5		C

	brz,a,pn %g3, L(shift_alot)	C

	 srlx	%o0, MAXSHIFT, %o0

	srlx	%o0, %g5, %l4		C new u, odd

	subcc	v0, %l4, %l2		C v - u, set flags for branch and movcc

	sub	%l4, v0, %o0		C u - v

	bnz,pt	%xcc, L(top)		C

	 and	%l2, MASK, %g3		C extract low MAXSHIFT bits from (v-u)

	return	%i7+8

	 sllx	%o2, %o4, %o0		C CAUTION: v0 alias for o2

L(shift_alot):

	b	L(mid)

	 and	%o0, MASK, %g3		C

EPILOGUE()