191 lines
3.6 KiB
NASM
191 lines
3.6 KiB
NASM
dnl x86 mpn_divexact_1 -- mpn by limb exact division.
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dnl Copyright 2001, 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 cycles/limb
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C P54 30.0
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C P55 29.0
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C P6 13.0 odd divisor, 12.0 even (strangely)
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C K6 14.0
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C K7 12.0
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C P4 42.0
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C mp_limb_t mpn_divexact_1 (mp_ptr dst, mp_srcptr src, mp_size_t size,
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C mp_limb_t divisor);
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C
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defframe(PARAM_DIVISOR,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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dnl re-use parameter space
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define(VAR_INVERSE,`PARAM_SRC')
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TEXT
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ALIGN(16)
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PROLOGUE(mpn_divexact_1)
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deflit(`FRAME',0)
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movl PARAM_DIVISOR, %eax
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pushl %ebp FRAME_pushl()
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movl PARAM_SIZE, %ebp
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pushl %edi FRAME_pushl()
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pushl %ebx FRAME_pushl()
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movl $-1, %ecx C shift count
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pushl %esi FRAME_pushl()
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L(strip_twos):
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incl %ecx
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shrl %eax
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jnc L(strip_twos)
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leal 1(%eax,%eax), %ebx C d without twos
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andl $127, %eax C d/2, 7 bits
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ifdef(`PIC',`
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call L(movl_eip_edx)
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addl $_GLOBAL_OFFSET_TABLE_, %edx
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movl modlimb_invert_table@GOT(%edx), %edx
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movzbl (%eax,%edx), %eax C inv 8 bits
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',`
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dnl non-PIC
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movzbl modlimb_invert_table(%eax), %eax C inv 8 bits
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')
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leal (%eax,%eax), %edx C 2*inv
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movl %ebx, PARAM_DIVISOR C d without twos
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imull %eax, %eax C inv*inv
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movl PARAM_SRC, %esi
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movl PARAM_DST, %edi
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imull %ebx, %eax C inv*inv*d
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subl %eax, %edx C inv = 2*inv - inv*inv*d
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leal (%edx,%edx), %eax C 2*inv
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imull %edx, %edx C inv*inv
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leal (%esi,%ebp,4), %esi C src end
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leal (%edi,%ebp,4), %edi C dst end
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negl %ebp C -size
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imull %ebx, %edx C inv*inv*d
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subl %edx, %eax C inv = 2*inv - inv*inv*d
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ASSERT(e,` C expect d*inv == 1 mod 2^BITS_PER_MP_LIMB
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pushl %eax FRAME_pushl()
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imull PARAM_DIVISOR, %eax
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cmpl $1, %eax
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popl %eax FRAME_popl()')
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movl %eax, VAR_INVERSE
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movl (%esi,%ebp,4), %eax C src[0]
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xorl %ebx, %ebx
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xorl %edx, %edx
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incl %ebp
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jz L(one)
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movl (%esi,%ebp,4), %edx C src[1]
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shrdl( %cl, %edx, %eax)
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movl VAR_INVERSE, %edx
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jmp L(entry)
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ALIGN(8)
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nop C k6 code alignment
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nop
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L(top):
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C eax q
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C ebx carry bit, 0 or -1
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C ecx shift
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C edx carry limb
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C esi src end
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C edi dst end
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C ebp counter, limbs, negative
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movl -4(%esi,%ebp,4), %eax
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subl %ebx, %edx C accumulate carry bit
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movl (%esi,%ebp,4), %ebx
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shrdl( %cl, %ebx, %eax)
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subl %edx, %eax C apply carry limb
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movl VAR_INVERSE, %edx
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sbbl %ebx, %ebx
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L(entry):
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imull %edx, %eax
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movl %eax, -4(%edi,%ebp,4)
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movl PARAM_DIVISOR, %edx
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mull %edx
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incl %ebp
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jnz L(top)
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movl -4(%esi), %eax C src high limb
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L(one):
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shrl %cl, %eax
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popl %esi FRAME_popl()
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addl %ebx, %eax C apply carry bit
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popl %ebx FRAME_popl()
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subl %edx, %eax C apply carry limb
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imull VAR_INVERSE, %eax
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movl %eax, -4(%edi)
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popl %edi
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popl %ebp
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ret
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ifdef(`PIC',`
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L(movl_eip_edx):
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movl (%esp), %edx
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ret_internal
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')
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EPILOGUE()
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