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93 lines
2.6 KiB
ArmAsm
93 lines
2.6 KiB
ArmAsm
/* mc68020 __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
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* store difference in a third limb vector.
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*
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* Copyright (C) 1992, 1994, 1996, 1998,
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* 2001 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*
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* Note: This code is heavily based on the GNU MP Library.
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* Actually it's the same code with only minor changes in the
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* way the data is stored; this is to support the abstraction
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* of an optional secure memory allocation which may be used
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* to avoid revealing of sensitive data due to paging etc.
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* The GNU MP Library itself is published under the LGPL;
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* however I decided to publish this code under the plain GPL.
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*/
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#include "sysdep.h"
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#include "asm-syntax.h"
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/*******************
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* mpi_limb_t
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* mpihelp_sub_n( mpi_ptr_t res_ptr, (sp + 4)
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* mpi_ptr_t s1_ptr, (sp + 8)
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* mpi_ptr_t s2_ptr, (sp + 16)
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* mpi_size_t size) (sp + 12)
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*/
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TEXT
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ALIGN
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GLOBL C_SYMBOL_NAME(mpihelp_sub_n)
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C_SYMBOL_NAME(mpihelp_sub_n:)
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PROLOG(mpihelp_sub_n)
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/* Save used registers on the stack. */
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movel R(d2),MEM_PREDEC(sp)
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movel R(a2),MEM_PREDEC(sp)
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/* Copy the arguments to registers. Better use movem? */
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movel MEM_DISP(sp,12),R(a2)
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movel MEM_DISP(sp,16),R(a0)
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movel MEM_DISP(sp,20),R(a1)
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movel MEM_DISP(sp,24),R(d2)
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eorw #1,R(d2)
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lsrl #1,R(d2)
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bcc L(L1)
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subql #1,R(d2) /* clears cy as side effect */
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L(Loop:)
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movel MEM_POSTINC(a0),R(d0)
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movel MEM_POSTINC(a1),R(d1)
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subxl R(d1),R(d0)
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movel R(d0),MEM_POSTINC(a2)
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L(L1:) movel MEM_POSTINC(a0),R(d0)
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movel MEM_POSTINC(a1),R(d1)
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subxl R(d1),R(d0)
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movel R(d0),MEM_POSTINC(a2)
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dbf R(d2),L(Loop) /* loop until 16 lsb of %4 == -1 */
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subxl R(d0),R(d0) /* d0 <= -cy; save cy as 0 or -1 in d0 */
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subl #0x10000,R(d2)
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bcs L(L2)
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addl R(d0),R(d0) /* restore cy */
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bra L(Loop)
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L(L2:)
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negl R(d0)
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/* Restore used registers from stack frame. */
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movel MEM_POSTINC(sp),R(a2)
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movel MEM_POSTINC(sp),R(d2)
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rts
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EPILOG(mpihelp_sub_n)
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