+++ /dev/null
-dnl AMD K6-2 mpn_rshift -- mpn right shift.
-dnl
-dnl K6-2: 1.75 cycles/limb
-
-
-dnl Copyright (C) 1999, 2000 Free Software Foundation, Inc.
-dnl
-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
-dnl modify it under the terms of the GNU Lesser General Public License as
-dnl published by the Free Software Foundation; either version 2.1 of the
-dnl License, or (at your option) any later version.
-dnl
-dnl The GNU MP Library is distributed in the hope that it will be useful,
-dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
-dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-dnl Lesser General Public License for more details.
-dnl
-dnl You should have received a copy of the GNU Lesser General Public
-dnl License along with the GNU MP Library; see the file COPYING.LIB. If
-dnl not, write to the Free Software Foundation, Inc., 59 Temple Place -
-dnl Suite 330, Boston, MA 02111-1307, USA.
-
-
-include(`../config.m4')
-
-
-C mp_limb_t mpn_rshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
-C unsigned shift);
-C
-
-defframe(PARAM_SHIFT,16)
-defframe(PARAM_SIZE, 12)
-defframe(PARAM_SRC, 8)
-defframe(PARAM_DST, 4)
-deflit(`FRAME',0)
-
-dnl Minimum 9, because the unrolled loop can't handle less.
-dnl
-deflit(UNROLL_THRESHOLD, 9)
-
- .text
- ALIGN(32)
-
-PROLOGUE(mpn_rshift)
-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
-
- shrdl( %cl, %edx, %eax) C return value
-
- shrl %cl, %edx
-
- movl %edx, (%ebx) C dst limb
- popl %ebx
-
- ret
-
-
-C -----------------------------------------------------------------------------
- ALIGN(16) C avoid offset 0x1f
-L(two_or_more):
- C eax size-1
- C ebx src
- C ecx shift
- C edx
-
- movl (%ebx), %edx C src low limb
- negl %ecx
-
- addl $32, %ecx
- movd PARAM_SHIFT, %mm6
-
- shll %cl, %edx
- cmpl $UNROLL_THRESHOLD-1, %eax
-
- jae L(unroll)
-
-
- C eax size-1
- C ebx src
- C ecx 32-shift
- C edx retval
- C
- C mm6 shift
-
- movl PARAM_DST, %ecx
- leal (%ebx,%eax,4), %ebx
-
- leal -4(%ecx,%eax,4), %ecx
- negl %eax
-
- C This loop runs at about 3 cycles/limb, which is the amount of
- C decoding, and this is despite every second access being unaligned.
-
-L(simple):
- C eax counter, -(size-1) to -1
- C ebx &src[size-1]
- C ecx &dst[size-1]
- C edx retval
- C
- C mm0 scratch
- C mm6 shift
-
-Zdisp( movq, 0,(%ebx,%eax,4), %mm0)
- incl %eax
-
- psrlq %mm6, %mm0
-
-Zdisp( movd, %mm0, 0,(%ecx,%eax,4))
- jnz L(simple)
-
-
- movq %mm0, (%ecx)
- movl %edx, %eax
-
- popl %ebx
-
- femms
- ret
-
-
-C -----------------------------------------------------------------------------
- ALIGN(16)
-L(unroll):
- C eax size-1
- C ebx src
- C ecx 32-shift
- C edx retval
- C
- C mm6 shift
-
- addl $32, %ecx
- subl $7, %eax C size-8
-
- movd %ecx, %mm7
- movl PARAM_DST, %ecx
-
- movq (%ebx), %mm2 C src low qword
- leal (%ebx,%eax,4), %ebx C src end - 32
-
- testb $4, %cl
- leal (%ecx,%eax,4), %ecx C dst end - 32
-
- notl %eax C -(size-7)
- jz L(dst_aligned)
-
- psrlq %mm6, %mm2
- incl %eax
-
-Zdisp( movd, %mm2, 0,(%ecx,%eax,4)) C dst low limb
- movq 4(%ebx,%eax,4), %mm2 C new src low qword
-L(dst_aligned):
-
- movq 12(%ebx,%eax,4), %mm0 C src second lowest qword
- nop C avoid bad cache line crossing
-
-
- C This loop is the important bit, the rest is just support for it.
- C Four src limbs are held at the start, and four more will be read.
- C Four dst limbs will be written. This schedule seems necessary for
- C full speed.
- C
- C The use of -(size-7) lets the loop stop when %eax becomes >= 0 and
- C and leaves 0 to 3 which can be tested with test $1 and $2.
-
-L(top):
- C eax counter, -(size-7) step by +4 until >=0
- C ebx src end - 32
- C ecx dst end - 32
- C edx retval
- C
- C mm0 src next qword
- C mm1 scratch
- C mm2 src prev qword
- C mm6 shift
- C mm7 64-shift
-
- psrlq %mm6, %mm2
- addl $4, %eax
-
- movq %mm0, %mm1
- psllq %mm7, %mm0
-
- por %mm0, %mm2
- movq 4(%ebx,%eax,4), %mm0
-
- psrlq %mm6, %mm1
- movq %mm2, -12(%ecx,%eax,4)
-
- movq %mm0, %mm2
- psllq %mm7, %mm0
-
- por %mm0, %mm1
- movq 12(%ebx,%eax,4), %mm0
-
- movq %mm1, -4(%ecx,%eax,4)
- ja L(top) C jump if no carry and not zero
-
-
-
- C Now have the four limbs in mm2 (low) and mm0 (high), and %eax is 0
- C to 3 representing respectively 3 to 0 further limbs.
-
- testl $2, %eax C testl to avoid bad cache line crossings
- jnz L(finish_nottwo)
-
- C Two or three extra limbs: rshift mm2, OR it with lshifted mm0, mm0
- C becomes new mm2 and a new mm0 is loaded.
-
- psrlq %mm6, %mm2
- movq %mm0, %mm1
-
- psllq %mm7, %mm0
- addl $2, %eax
-
- por %mm0, %mm2
- movq 12(%ebx,%eax,4), %mm0
-
- movq %mm2, -4(%ecx,%eax,4)
- movq %mm1, %mm2
-L(finish_nottwo):
-
-
- testb $1, %al
- psrlq %mm6, %mm2
-
- movq %mm0, %mm1
- psllq %mm7, %mm0
-
- por %mm0, %mm2
- psrlq %mm6, %mm1
-
- movq %mm2, 4(%ecx,%eax,4)
- jnz L(finish_even)
-
-
- C one further extra limb to process
-
- movd 32-4(%ebx), %mm0 C src[size-1], most significant limb
- popl %ebx
-
- movq %mm0, %mm2
- psllq %mm7, %mm0
-
- por %mm0, %mm1
- psrlq %mm6, %mm2
-
- movq %mm1, 32-12(%ecx) C dst[size-3,size-2]
- movd %mm2, 32-4(%ecx) C dst[size-1]
-
- movl %edx, %eax C retval
-
- femms
- ret
-
-
- nop C avoid bad cache line crossing
-L(finish_even):
- C no further extra limbs
-
- movq %mm1, 32-8(%ecx) C dst[size-2,size-1]
- movl %edx, %eax C retval
-
- popl %ebx
-
- femms
- ret
-
-EPILOGUE()
projects / ghc-hetmet.git / blobdiff