diff options
Diffstat (limited to 'rts/gmp/mpn/x86/k7/diveby3.asm')
| -rw-r--r-- | rts/gmp/mpn/x86/k7/diveby3.asm | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/rts/gmp/mpn/x86/k7/diveby3.asm b/rts/gmp/mpn/x86/k7/diveby3.asm new file mode 100644 index 0000000000..57684958a5 --- /dev/null +++ b/rts/gmp/mpn/x86/k7/diveby3.asm @@ -0,0 +1,131 @@ +dnl AMD K7 mpn_divexact_by3 -- mpn division by 3, expecting no remainder. +dnl +dnl K7: 8.0 cycles/limb + + +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. + + +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 floor(b*2/3) where b=2^32 +deflit(ONE_THIRD_CEIL, 0x55555556) +deflit(TWO_THIRDS_FLOOR, 0xAAAAAAAA) + + .text + ALIGN(32) + +PROLOGUE(mpn_divexact_by3c) +deflit(`FRAME',0) + + movl PARAM_SRC, %ecx + pushl %ebx defframe_pushl(SAVE_EBX) + + movl PARAM_CARRY, %ebx + pushl %ebp defframe_pushl(SAVE_EBP) + + movl PARAM_SIZE, %ebp + pushl %edi defframe_pushl(SAVE_EDI) + + movl (%ecx), %eax C src low limb + pushl %esi defframe_pushl(SAVE_ESI) + + movl PARAM_DST, %edi + movl $TWO_THIRDS_FLOOR, %esi + leal -4(%ecx,%ebp,4), %ecx C &src[size-1] + + subl %ebx, %eax + + setc %bl + decl %ebp + jz L(last) + + leal (%edi,%ebp,4), %edi C &dst[size-1] + negl %ebp + + + ALIGN(16) +L(top): + C eax src limb, carry subtracted + C ebx carry limb (0 or 1) + C ecx &src[size-1] + C edx scratch + C esi TWO_THIRDS_FLOOR + C edi &dst[size-1] + C ebp counter, limbs, negative + + imull $INVERSE_3, %eax, %edx + + movl 4(%ecx,%ebp,4), %eax C next src limb + cmpl $ONE_THIRD_CEIL, %edx + + sbbl $-1, %ebx C +1 if result>=ceil(b/3) + cmpl %edx, %esi + + sbbl %ebx, %eax C and further 1 if result>=ceil(b*2/3) + movl %edx, (%edi,%ebp,4) + incl %ebp + + setc %bl C new carry + jnz L(top) + + + +L(last): + C eax src limb, carry subtracted + C ebx carry limb (0 or 1) + C ecx &src[size-1] + C edx scratch + C esi multiplier + C edi &dst[size-1] + C ebp + + imull $INVERSE_3, %eax + + cmpl $ONE_THIRD_CEIL, %eax + movl %eax, (%edi) + movl SAVE_EBP, %ebp + + sbbl $-1, %ebx C +1 if eax>=ceil(b/3) + cmpl %eax, %esi + movl $0, %eax + + adcl %ebx, %eax C further +1 if eax>=ceil(b*2/3) + movl SAVE_EDI, %edi + movl SAVE_ESI, %esi + + movl SAVE_EBX, %ebx + addl $FRAME, %esp + + ret + +EPILOGUE() |