286 lines
5.3 KiB
NASM
286 lines
5.3 KiB
NASM
dnl AMD K6-2 mpn_lshift -- mpn left shift.
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dnl Copyright 1999, 2000, 2002 Free Software Foundation, Inc.
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dnl
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dnl This file is part of the GNU MP Library.
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dnl
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dnl The GNU MP Library is free software; you can redistribute it and/or
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dnl modify it under the terms of the GNU Lesser General Public License as
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dnl published by the Free Software Foundation; either version 2.1 of the
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dnl License, or (at your option) any later version.
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dnl
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dnl The GNU MP Library is distributed in the hope that it will be useful,
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dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
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dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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dnl Lesser General Public License for more details.
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dnl
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dnl You should have received a copy of the GNU Lesser General Public
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dnl License along with the GNU MP Library; see the file COPYING.LIB. If
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dnl not, write to the Free Software Foundation, Inc., 51 Franklin Street,
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dnl Fifth Floor, Boston, MA 02110-1301, USA.
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include(`../config.m4')
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C K6-2: 1.75 cycles/limb
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C mp_limb_t mpn_lshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
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C unsigned shift);
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C
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defframe(PARAM_SHIFT,16)
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defframe(PARAM_SIZE, 12)
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defframe(PARAM_SRC, 8)
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defframe(PARAM_DST, 4)
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deflit(`FRAME',0)
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dnl used after src has been fetched
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define(VAR_RETVAL,`PARAM_SRC')
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dnl minimum 9, because unrolled loop can't handle less
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deflit(UNROLL_THRESHOLD, 9)
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TEXT
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ALIGN(32)
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PROLOGUE(mpn_lshift)
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deflit(`FRAME',0)
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C The 1 limb case can be done without the push %ebx, but it's then
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C still the same speed. The push is left as a free helping hand for
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C the two_or_more code.
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movl PARAM_SIZE, %eax
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pushl %ebx FRAME_pushl()
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movl PARAM_SRC, %ebx
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decl %eax
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movl PARAM_SHIFT, %ecx
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jnz L(two_or_more)
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movl (%ebx), %edx C src limb
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movl PARAM_DST, %ebx
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shldl( %cl, %edx, %eax) C return value
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shll %cl, %edx
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movl %edx, (%ebx) C dst limb
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popl %ebx
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ret
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C -----------------------------------------------------------------------------
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ALIGN(16) C avoid offset 0x1f
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L(two_or_more):
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C eax size-1
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C ebx src
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C ecx shift
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C edx
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movl (%ebx,%eax,4), %edx C src high limb
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negl %ecx
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movd PARAM_SHIFT, %mm6
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addl $32, %ecx C 32-shift
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shrl %cl, %edx
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cmpl $UNROLL_THRESHOLD-1, %eax
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movl %edx, VAR_RETVAL
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jae L(unroll)
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movd %ecx, %mm7
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movl %eax, %ecx
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movl PARAM_DST, %eax
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L(simple):
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C eax dst
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C ebx src
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C ecx counter, size-1 to 1
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C edx retval
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C
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C mm0 scratch
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C mm6 shift
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C mm7 32-shift
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movq -4(%ebx,%ecx,4), %mm0
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psrlq %mm7, %mm0
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Zdisp( movd, %mm0, 0,(%eax,%ecx,4))
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loop L(simple)
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movd (%ebx), %mm0
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popl %ebx
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psllq %mm6, %mm0
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movd %mm0, (%eax)
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movl %edx, %eax
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femms
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ret
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C -----------------------------------------------------------------------------
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ALIGN(16)
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L(unroll):
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C eax size-1
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C ebx src
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C ecx 32-shift
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C edx retval (but instead VAR_RETVAL is used)
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C
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C mm6 shift
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addl $32, %ecx
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movl PARAM_DST, %edx
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movd %ecx, %mm7
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subl $7, %eax C size-8
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leal (%edx,%eax,4), %ecx C alignment of dst
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movq 32-8(%ebx,%eax,4), %mm2 C src high qword
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testb $4, %cl
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jz L(dst_aligned)
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psllq %mm6, %mm2
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psrlq $32, %mm2
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decl %eax
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movd %mm2, 32(%edx,%eax,4) C dst high limb
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movq 32-8(%ebx,%eax,4), %mm2 C new src high qword
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L(dst_aligned):
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movq 32-16(%ebx,%eax,4), %mm0 C src second highest qword
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C This loop is the important bit, the rest is just support for it.
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C Four src limbs are held at the start, and four more will be read.
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C Four dst limbs will be written. This schedule seems necessary for
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C full speed.
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C
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C The use of size-8 lets the loop stop when %eax goes negative and
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C leaves -4 to -1 which can be tested with test $1 and $2.
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L(top):
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C eax counter, size-8 step by -4 until <0
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C ebx src
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C ecx
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C edx dst
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C
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C mm0 src next qword
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C mm1 scratch
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C mm2 src prev qword
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C mm6 shift
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C mm7 64-shift
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psllq %mm6, %mm2
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subl $4, %eax
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movq %mm0, %mm1
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psrlq %mm7, %mm0
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por %mm0, %mm2
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movq 24(%ebx,%eax,4), %mm0
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psllq %mm6, %mm1
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movq %mm2, 40(%edx,%eax,4)
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movq %mm0, %mm2
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psrlq %mm7, %mm0
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por %mm0, %mm1
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movq 16(%ebx,%eax,4), %mm0
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movq %mm1, 32(%edx,%eax,4)
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jnc L(top)
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C Now have four limbs in mm2 (prev) and mm0 (next), plus eax mod 4.
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C
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C 8(%ebx) is the next source, and 24(%edx) is the next destination.
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C %eax is between -4 and -1, representing respectively 0 to 3 extra
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C limbs that must be read.
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testl $2, %eax C testl to avoid bad cache line crossing
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jz L(finish_nottwo)
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C Two more limbs: lshift mm2, OR it with rshifted mm0, mm0 becomes
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C new mm2 and a new mm0 is loaded.
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psllq %mm6, %mm2
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movq %mm0, %mm1
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psrlq %mm7, %mm0
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subl $2, %eax
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por %mm0, %mm2
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movq 16(%ebx,%eax,4), %mm0
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movq %mm2, 32(%edx,%eax,4)
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movq %mm1, %mm2
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L(finish_nottwo):
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C lshift mm2, OR with rshifted mm0, mm1 becomes lshifted mm0
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testb $1, %al
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psllq %mm6, %mm2
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movq %mm0, %mm1
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psrlq %mm7, %mm0
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por %mm0, %mm2
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psllq %mm6, %mm1
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movq %mm2, 24(%edx,%eax,4)
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jz L(finish_even)
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C Size is odd, so mm1 and one extra limb to process.
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movd (%ebx), %mm0 C src[0]
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popl %ebx
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deflit(`FRAME',0)
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movq %mm0, %mm2
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psllq $32, %mm0
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psrlq %mm7, %mm0
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psllq %mm6, %mm2
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por %mm0, %mm1
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movq %mm1, 4(%edx) C dst[1,2]
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movd %mm2, (%edx) C dst[0]
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movl VAR_RETVAL, %eax
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femms
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ret
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nop C avoid bad cache line crossing
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L(finish_even):
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deflit(`FRAME',4)
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C Size is even, so only mm1 left to process.
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movq %mm1, (%edx) C dst[0,1]
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movl VAR_RETVAL, %eax
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popl %ebx
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femms
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ret
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EPILOGUE()
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