138 lines
3.1 KiB
NASM
138 lines
3.1 KiB
NASM
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dnl AMD K6 mpn_preinv_mod_1 -- mpn by 1 remainder, with pre-inverted divisor.
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dnl Copyright 2000, 2002, 2003 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: 18.0 cycles/limb
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C mp_limb_t mpn_preinv_mod_1 (mp_srcptr src, mp_size_t size, mp_limb_t divisor,
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C mp_limb_t inverse);
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C
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C This code is only 2 c/l faster than a simple divl, but that's 10% so it's
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C considered worthwhile (just).
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defframe(PARAM_INVERSE,16)
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defframe(PARAM_DIVISOR,12)
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defframe(PARAM_SIZE, 8)
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defframe(PARAM_SRC, 4)
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TEXT
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ALIGN(32)
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PROLOGUE(mpn_preinv_mod_1)
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deflit(`FRAME',0)
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ASSERT(ae,`cmpl $1, PARAM_SIZE')
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ASSERT(nz,`testl $0x80000000, PARAM_DIVISOR')
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movl PARAM_SIZE, %ecx
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pushl %ebp FRAME_pushl()
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movl PARAM_SRC, %ebp
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pushl %edi FRAME_pushl()
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movl PARAM_DIVISOR, %eax
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pushl %esi FRAME_pushl()
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movl -4(%ebp,%ecx,4), %esi C src high limb
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pushl %ebx FRAME_pushl()
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movl %edx, %edi C first n2 to cancel
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subl %eax, %esi C first n1 = high-divisor
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decl %ecx
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jz L(done_sbbl)
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L(top):
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C eax scratch
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C ebx n10, nadj, q1
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C ecx counter, size to 1
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C edx scratch
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C esi n2
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C edi old high, for underflow test
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C ebp src
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sbbl %edx, %edi C high n-(q1+1)*d, 0 or -1
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L(entry):
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andl PARAM_DIVISOR, %edi
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L(q1_ff_top):
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movl -4(%ebp,%ecx,4), %ebx
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addl %esi, %edi C possible addback
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movl %ebx, %esi C n10
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sarl $31, %ebx C -n1 = 0 or -1
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movl %edi, %eax C n2
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movl PARAM_INVERSE, %edx
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subl %ebx, %eax C n2+n1
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mull %edx C m*(n2+n1)
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andl PARAM_DIVISOR, %ebx C -n1 & d
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addl %esi, %ebx C nadj = n10 + (-n1&d), ignoring overflow
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addl %ebx, %eax C low m*(n2+n1) + nadj, giving carry flag
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leal 1(%edi), %ebx C n2+1
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adcl %ebx, %edx C 1+high(n2<<32+m*(n2+n1)+nadj) = q1+1
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movl PARAM_DIVISOR, %eax C d
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jz L(q1_ff)
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mull %edx C (q1+1)*d
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subl %eax, %esi C low n-(q1+1)*d
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loop L(top)
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L(done_sbbl):
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sbbl %edx, %edi C high n-(q1+1)*d, 0 or -1
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andl PARAM_DIVISOR, %edi
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L(done_esi_edi):
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popl %ebx
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leal (%esi,%edi), %eax
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popl %esi
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popl %edi
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popl %ebp
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ret
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C Special case for q1=0xFFFFFFFF, giving q=0xFFFFFFFF meaning the low dword
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C of q*d is simply -d and the remainder n-q*d = n10+d. This is rarely
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C reached.
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L(q1_ff):
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movl PARAM_DIVISOR, %edi
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loop L(q1_ff_top)
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jmp L(done_esi_edi)
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EPILOGUE()
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