1/* mc68020 __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and 2 * store difference in a third limb vector. 3 * 4 * Copyright (C) 1992, 1994, 1996, 1998, 5 * 2001, 2002 Free Software Foundation, Inc. 6 * 7 * This file is part of Libgcrypt. 8 * 9 * Libgcrypt is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU Lesser General Public License as 11 * published by the Free Software Foundation; either version 2.1 of 12 * the License, or (at your option) any later version. 13 * 14 * Libgcrypt is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 22 * 23 * Note: This code is heavily based on the GNU MP Library. 24 * Actually it's the same code with only minor changes in the 25 * way the data is stored; this is to support the abstraction 26 * of an optional secure memory allocation which may be used 27 * to avoid revealing of sensitive data due to paging etc. 28 */ 29 30#include "sysdep.h" 31#include "asm-syntax.h" 32 33 34/******************* 35 * mpi_limb_t 36 * _gcry_mpih_sub_n( mpi_ptr_t res_ptr, (sp + 4) 37 * mpi_ptr_t s1_ptr, (sp + 8) 38 * mpi_ptr_t s2_ptr, (sp + 16) 39 * mpi_size_t size) (sp + 12) 40 */ 41 42 43 TEXT 44 ALIGN 45 GLOBL C_SYMBOL_NAME(_gcry_mpih_sub_n) 46 47C_SYMBOL_NAME(_gcry_mpih_sub_n:) 48PROLOG(_gcry_mpih_sub_n) 49/* Save used registers on the stack. */ 50 movel R(d2),MEM_PREDEC(sp) 51 movel R(a2),MEM_PREDEC(sp) 52 53/* Copy the arguments to registers. Better use movem? */ 54 movel MEM_DISP(sp,12),R(a2) 55 movel MEM_DISP(sp,16),R(a0) 56 movel MEM_DISP(sp,20),R(a1) 57 movel MEM_DISP(sp,24),R(d2) 58 59 eorw #1,R(d2) 60 lsrl #1,R(d2) 61 bcc L(L1) 62 subql #1,R(d2) /* clears cy as side effect */ 63 64L(Loop:) 65 movel MEM_POSTINC(a0),R(d0) 66 movel MEM_POSTINC(a1),R(d1) 67 subxl R(d1),R(d0) 68 movel R(d0),MEM_POSTINC(a2) 69L(L1:) movel MEM_POSTINC(a0),R(d0) 70 movel MEM_POSTINC(a1),R(d1) 71 subxl R(d1),R(d0) 72 movel R(d0),MEM_POSTINC(a2) 73 74 dbf R(d2),L(Loop) /* loop until 16 lsb of %4 == -1 */ 75 subxl R(d0),R(d0) /* d0 <= -cy; save cy as 0 or -1 in d0 */ 76 subl #0x10000,R(d2) 77 bcs L(L2) 78 addl R(d0),R(d0) /* restore cy */ 79 bra L(Loop) 80 81L(L2:) 82 negl R(d0) 83 84/* Restore used registers from stack frame. */ 85 movel MEM_POSTINC(sp),R(a2) 86 movel MEM_POSTINC(sp),R(d2) 87 88 rts 89EPILOG(_gcry_mpih_sub_n) 90 91 92