diff options
Diffstat (limited to 'rts/gmp/mpn/x86/diveby3.asm')
| -rw-r--r-- | rts/gmp/mpn/x86/diveby3.asm | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/rts/gmp/mpn/x86/diveby3.asm b/rts/gmp/mpn/x86/diveby3.asm new file mode 100644 index 0000000000..df879da9e1 --- /dev/null +++ b/rts/gmp/mpn/x86/diveby3.asm @@ -0,0 +1,115 @@ +dnl x86 mpn_divexact_by3 -- mpn division by 3, expecting no remainder. + + +dnl Copyright (C) 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. + + +dnl The following all have their own optimized versions of this routine, +dnl but for reference the code here runs as follows. +dnl +dnl cycles/limb +dnl P54 18.0 +dnl P55 17.0 +dnl P6 14.5 +dnl K6 14.0 +dnl K7 10.0 + + +include(`../config.m4') + + +C mp_limb_t mpn_divexact_by3c (mp_ptr dst, mp_srcptr src, mp_size_t size, +C mp_limb_t carry); + +defframe(PARAM_CARRY,16) +defframe(PARAM_SIZE, 12) +defframe(PARAM_SRC, 8) +defframe(PARAM_DST, 4) + +dnl multiplicative inverse of 3, modulo 2^32 +deflit(INVERSE_3, 0xAAAAAAAB) + +dnl ceil(b/3) and ceil(b*2/3) where b=2^32 +deflit(ONE_THIRD_CEIL, 0x55555556) +deflit(TWO_THIRDS_CEIL, 0xAAAAAAAB) + + .text + ALIGN(8) + +PROLOGUE(mpn_divexact_by3c) +deflit(`FRAME',0) + + movl PARAM_SRC, %ecx + pushl %ebp FRAME_pushl() + + movl PARAM_SIZE, %ebp + pushl %edi FRAME_pushl() + + movl PARAM_DST, %edi + pushl %esi FRAME_pushl() + + movl $INVERSE_3, %esi + pushl %ebx FRAME_pushl() + + leal (%ecx,%ebp,4), %ecx + movl PARAM_CARRY, %ebx + + leal (%edi,%ebp,4), %edi + negl %ebp + + + ALIGN(8) +L(top): + C eax scratch, low product + C ebx carry limb (0 to 3) + C ecx &src[size] + C edx scratch, high product + C esi multiplier + C edi &dst[size] + C ebp counter, limbs, negative + + movl (%ecx,%ebp,4), %eax + + subl %ebx, %eax + + setc %bl + + imull %esi + + cmpl $ONE_THIRD_CEIL, %eax + movl %eax, (%edi,%ebp,4) + + sbbl $-1, %ebx C +1 if eax>=ceil(b/3) + cmpl $TWO_THIRDS_CEIL, %eax + + sbbl $-1, %ebx C +1 if eax>=ceil(b*2/3) + incl %ebp + + jnz L(top) + + + movl %ebx, %eax + popl %ebx + popl %esi + popl %edi + popl %ebp + ret + +EPILOGUE() |