Annotation of OpenXM_contrib/gmp/mpn/x86/k6/mmx/rshift.asm, Revision 1.1
1.1 ! maekawa 1: dnl AMD K6 mpn_rshift -- mpn right shift.
! 2: dnl
! 3: dnl K6: 3.0 cycles/limb
! 4:
! 5:
! 6: dnl Copyright (C) 1999, 2000 Free Software Foundation, Inc.
! 7: dnl
! 8: dnl This file is part of the GNU MP Library.
! 9: dnl
! 10: dnl The GNU MP Library is free software; you can redistribute it and/or
! 11: dnl modify it under the terms of the GNU Lesser General Public License as
! 12: dnl published by the Free Software Foundation; either version 2.1 of the
! 13: dnl License, or (at your option) any later version.
! 14: dnl
! 15: dnl The GNU MP Library is distributed in the hope that it will be useful,
! 16: dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
! 17: dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
! 18: dnl Lesser General Public License for more details.
! 19: dnl
! 20: dnl You should have received a copy of the GNU Lesser General Public
! 21: dnl License along with the GNU MP Library; see the file COPYING.LIB. If
! 22: dnl not, write to the Free Software Foundation, Inc., 59 Temple Place -
! 23: dnl Suite 330, Boston, MA 02111-1307, USA.
! 24:
! 25:
! 26: include(`../config.m4')
! 27:
! 28:
! 29: C mp_limb_t mpn_rshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
! 30: C unsigned shift);
! 31: C
! 32: C The loop runs at 3 cycles/limb, limited by decoding and by having 3 mmx
! 33: C instructions. This is despite every second fetch being unaligned.
! 34:
! 35:
! 36: defframe(PARAM_SHIFT,16)
! 37: defframe(PARAM_SIZE, 12)
! 38: defframe(PARAM_SRC, 8)
! 39: defframe(PARAM_DST, 4)
! 40: deflit(`FRAME',0)
! 41:
! 42: .text
! 43: ALIGN(32)
! 44:
! 45: PROLOGUE(mpn_rshift)
! 46: deflit(`FRAME',0)
! 47:
! 48: C The 1 limb case can be done without the push %ebx, but it's then
! 49: C still the same speed. The push is left as a free helping hand for
! 50: C the two_or_more code.
! 51:
! 52: movl PARAM_SIZE, %eax
! 53: pushl %ebx FRAME_pushl()
! 54:
! 55: movl PARAM_SRC, %ebx
! 56: decl %eax
! 57:
! 58: movl PARAM_SHIFT, %ecx
! 59: jnz L(two_or_more)
! 60:
! 61: movl (%ebx), %edx C src limb
! 62: movl PARAM_DST, %ebx
! 63:
! 64: shrdl( %cl, %edx, %eax) C return value
! 65:
! 66: shrl %cl, %edx
! 67:
! 68: movl %edx, (%ebx) C dst limb
! 69: popl %ebx
! 70:
! 71: ret
! 72:
! 73:
! 74: ALIGN(16) C avoid offset 0x1f
! 75: L(two_or_more):
! 76: C eax size-1
! 77: C ebx src
! 78: C ecx shift
! 79: C edx
! 80:
! 81: movl (%ebx), %edx C src low limb
! 82: negl %ecx
! 83:
! 84: addl $32, %ecx C 32-shift
! 85: movd PARAM_SHIFT, %mm6
! 86:
! 87: shll %cl, %edx C retval
! 88: movl PARAM_DST, %ecx
! 89:
! 90: leal (%ebx,%eax,4), %ebx
! 91:
! 92: leal -4(%ecx,%eax,4), %ecx
! 93: negl %eax
! 94:
! 95:
! 96: L(simple):
! 97: C eax counter (negative)
! 98: C ebx &src[size-1]
! 99: C ecx &dst[size-1]
! 100: C edx retval
! 101: C
! 102: C mm0 scratch
! 103: C mm6 shift
! 104:
! 105: Zdisp( movq, 0,(%ebx,%eax,4), %mm0)
! 106: incl %eax
! 107:
! 108: psrlq %mm6, %mm0
! 109:
! 110: Zdisp( movd, %mm0, 0,(%ecx,%eax,4))
! 111: jnz L(simple)
! 112:
! 113:
! 114: movq %mm0, (%ecx)
! 115: movl %edx, %eax
! 116:
! 117: popl %ebx
! 118:
! 119: emms
! 120: ret
! 121:
! 122: EPILOGUE()
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