/* PowerPC-32 lshift
 * Copyright (C) 1995, 1996, 1997, 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "sysdep.h"
#include "asm-syntax.h"


#ifndef USE_PPC_PATCHES

/*******************
 * mpi_limb_t
 * mpihelp_lshift( mpi_ptr_t wp,	(r3)
 *		   mpi_ptr_t up,	(r4)
 *		   mpi_size_t usize,	(r5)
 *		   unsigned cnt)	(r6)
 */

	.toc
.csect	.text[PR]
	.align	2
	.globl	mpihelp_lshift
	.globl	.mpihelp_lshift
	.csect	mpihelp_lshift[DS]
mpihelp_lshift:
	.long	.mpihelp_lshift,  TOC[tc0],	  0
	.csect	.text[PR]
.mpihelp_lshift:
	mtctr	5		# copy size into CTR
	slwi	0,5,2
	add	7,3,0		# make r7 point at end of res
	add	4,4,0		# make r4 point at end of s1
	subfic	8,6,32
	lwzu	11,-4(4)	# load first s1 limb
	srw	3,11,8		# compute function return value
	bdz	Lend1

Loop:	lwzu	10,-4(4)
	slw	9,11,6
	srw	12,10,8
	or	9,9,12
	stwu	9,-4(7)
	bdz	Lend2
	lwzu	11,-4(4)
	slw	9,10,6
	srw	12,11,8
	or	9,9,12
	stwu	9,-4(7)
	bdnz	Loop

Lend1:	slw	0,11,6
	stw	0,-4(7)
	blr

Lend2:	slw	0,10,6
	stw	0,-4(7)
	blr

#else
        
/* mp_limb_t mpn_lshift (mp_ptr wp, mp_srcptr up, mp_size_t usize,
			unsigned int cnt)  */

EALIGN(mpihelp_lshift,3,0)
       mtctr   %r5	       # copy size into CTR
       cmplwi  %cr0,%r5,16     # is size < 16
       slwi    %r0,%r5,2
       add     %r7,%r3,%r0     # make r7 point at end of res
       add     %r4,%r4,%r0     # make r4 point at end of s1
       lwzu    %r11,-4(%r4)    # load first s1 limb
       subfic  %r8,%r6,32
       srw     %r3,%r11,%r8    # compute function return value
       bge     %cr0,L(big)     # branch if size >= 16

       bdz     L(end1)

0:     lwzu    %r10,-4(%r4)
       slw     %r9,%r11,%r6
       srw     %r12,%r10,%r8
       or      %r9,%r9,%r12
       stwu    %r9,-4(%r7)
       bdz     L(end2)
       lwzu    %r11,-4(%r4)
       slw     %r9,%r10,%r6
       srw     %r12,%r11,%r8
       or      %r9,%r9,%r12
       stwu    %r9,-4(%r7)
       bdnz    0b

L(end1):slw    %r0,%r11,%r6
       stw     %r0,-4(%r7)
       blr


/* Guaranteed not to succeed.  */
L(boom): tweq	 %r0,%r0

/* We imitate a case statement, by using (yuk!) fixed-length code chunks,
   of size 4*12 bytes.	We have to do this (or something) to make this PIC.  */
L(big):        mflr    %r9
       bltl-   %cr0,L(boom)    # Never taken, only used to set LR.
       slwi    %r10,%r6,4
       mflr    %r12
       add     %r10,%r12,%r10
       slwi    %r8,%r6,5
       add     %r10,%r8,%r10
       mtctr   %r10
       addi    %r5,%r5,-1
       mtlr    %r9
       bctr

L(end2):slw    %r0,%r10,%r6
       stw     %r0,-4(%r7)
       blr

#define DO_LSHIFT(n) \
       mtctr   %r5;						       \
0:     lwzu    %r10,-4(%r4);					       \
       slwi    %r9,%r11,n;					       \
       inslwi  %r9,%r10,n,32-n; 				       \
       stwu    %r9,-4(%r7);					       \
       bdz-    L(end2); 					       \
       lwzu    %r11,-4(%r4);					       \
       slwi    %r9,%r10,n;					       \
       inslwi  %r9,%r11,n,32-n; 				       \
       stwu    %r9,-4(%r7);					       \
       bdnz    0b;						       \
       b       L(end1)

       DO_LSHIFT(1)
       DO_LSHIFT(2)
       DO_LSHIFT(3)
       DO_LSHIFT(4)
       DO_LSHIFT(5)
       DO_LSHIFT(6)
       DO_LSHIFT(7)
       DO_LSHIFT(8)
       DO_LSHIFT(9)
       DO_LSHIFT(10)
       DO_LSHIFT(11)
       DO_LSHIFT(12)
       DO_LSHIFT(13)
       DO_LSHIFT(14)
       DO_LSHIFT(15)
       DO_LSHIFT(16)
       DO_LSHIFT(17)
       DO_LSHIFT(18)
       DO_LSHIFT(19)
       DO_LSHIFT(20)
       DO_LSHIFT(21)
       DO_LSHIFT(22)
       DO_LSHIFT(23)
       DO_LSHIFT(24)
       DO_LSHIFT(25)
       DO_LSHIFT(26)
       DO_LSHIFT(27)
       DO_LSHIFT(28)
       DO_LSHIFT(29)
       DO_LSHIFT(30)
       DO_LSHIFT(31)

END(mpihelp_lshift)
#endif
