dnl AMD K6 mpn_lshift -- mpn left shift.
dnl Copyright 1999, 2000, 2002 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 K6: 3.0 cycles/limb
C mp_limb_t mpn_lshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
C unsigned shift)
;
C
C The loop runs at 3 cycles/limb, limited by decoding
and by having 3 mmx
C instructions.
This is despite every second fetch being unaligned.
defframe(PARAM_SHIFT,16)
defframe(PARAM_SIZE, 12)
defframe(PARAM_SRC, 8)
defframe(PARAM_DST, 4)
TEXT
ALIGN(32)
PROLOGUE(mpn_lshift)
deflit(`FRAME
',0)
C The 1 limb case can be done without the
push %ebx, but it
's then
C still the same speed. The
push is left as a free helping hand
for
C the two_or_more
code.
movl PARAM_SIZE, %
eax
pushl %ebx FRAME_pushl()
movl PARAM_SRC, %ebx
decl %
eax
movl PARAM_SHIFT, %
ecx
jnz L(two_or_more)
movl (%ebx), %
edx C src limb
movl PARAM_DST, %ebx
shldl( %cl, %
edx, %
eax) C return value
shll %cl, %
edx
movl %
edx, (%ebx) C dst limb
popl %ebx
ret
ALIGN(16) C avoid offset 0x1f
nop C avoid bad cache
line crossing
L(two_or_more):
C
eax size-1
C ebx src
C
ecx shift
C
edx
movl (%ebx,%
eax,4), %
edx C src high limb
negl %
ecx
movd PARAM_SHIFT, %mm6
addl $32, %
ecx C 32-shift
shrl %cl, %
edx
movd %
ecx, %mm7
movl PARAM_DST, %
ecx
L(top):
C
eax counter, size-1 to 1
C ebx src
C
ecx dst
C
edx retval
C
C mm0 scratch
C mm6 shift
C mm7 32-shift
movq -4(%ebx,%
eax,4), %mm0
decl %
eax
psrlq %mm7, %mm0
movd %mm0, 4(%
ecx,%
eax,4)
jnz L(top)
movd (%ebx), %mm0
popl %ebx
psllq %mm6, %mm0
movl %
edx, %
eax
movd %mm0, (%
ecx)
emms
ret
EPILOGUE()
