| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 2 | /* mpihelp-sub.c - MPI helper functions |
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| 3 | * Copyright (C) 1994, 1996 Free Software Foundation, Inc. |
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| 4 | * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. |
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| 5 | * |
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| 6 | * This file is part of GnuPG. |
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| 7 | * |
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| 8 | * Note: This code is heavily based on the GNU MP Library. |
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| 9 | * Actually it's the same code with only minor changes in the |
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| 10 | * way the data is stored; this is to support the abstraction |
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| 11 | * of an optional secure memory allocation which may be used |
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| 12 | * to avoid revealing of sensitive data due to paging etc. |
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| 13 | * The GNU MP Library itself is published under the LGPL; |
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| 14 | * however I decided to publish this code under the plain GPL. |
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| 15 | */ |
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| 16 | |
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| 17 | #include "mpi-internal.h" |
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| 18 | |
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| 19 | /**************** |
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| 20 | * Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE. |
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| 21 | * There are no restrictions on the relative sizes of |
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| 22 | * the two arguments. |
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| 23 | * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2. |
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| 24 | */ |
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| 25 | int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size) |
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| 26 | { |
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| 27 | mpi_size_t i; |
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| 28 | mpi_limb_t op1_word, op2_word; |
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| 29 | |
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| 30 | for (i = size - 1; i >= 0; i--) { |
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| 31 | op1_word = op1_ptr[i]; |
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| 32 | op2_word = op2_ptr[i]; |
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| 33 | if (op1_word != op2_word) |
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| 34 | goto diff; |
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| 35 | } |
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| 36 | return 0; |
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| 37 | |
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| 38 | diff: |
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| 39 | /* This can *not* be simplified to |
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| 40 | * op2_word - op2_word |
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| 41 | * since that expression might give signed overflow. */ |
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| 42 | return (op1_word > op2_word) ? 1 : -1; |
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| 43 | } |
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| 44 | |
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