125 lines
3.4 KiB
C
125 lines
3.4 KiB
C
/* Utilities for reading leb128 values.
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Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the libiberty library.
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Libiberty is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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Libiberty 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 GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with libiberty; see the file COPYING.LIB. If not, write
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to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
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Boston, MA 02110-1301, USA. */
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/* The functions defined here can be speed critical.
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Since they are all pretty small we keep things simple and just define
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them all as "static inline". */
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#ifndef LEB128_H
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#define LEB128_H
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/* Get a definition for inline. */
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#include "ansidecl.h"
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/* Get a definition for NULL, size_t. */
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#include <stddef.h>
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/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
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by R, and return the number of bytes read.
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If we read off the end of the buffer, zero is returned,
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and nothing is stored in R.
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Note: The result is an int instead of a pointer to the next byte to be
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read to avoid const-vs-non-const problems. */
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static inline size_t
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read_uleb128_to_ull (const unsigned char *buf, const unsigned char *buf_end,
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unsigned long long *r)
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{
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const unsigned char *p = buf;
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unsigned int shift = 0;
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unsigned long long result = 0;
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unsigned char byte;
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while (1)
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{
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if (p >= buf_end)
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return 0;
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byte = *p++;
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result |= ((unsigned long long) (byte & 0x7f)) << shift;
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if ((byte & 0x80) == 0)
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break;
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shift += 7;
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}
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*r = result;
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return p - buf;
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}
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/* Decode the signed LEB128 constant at BUF into the variable pointed to
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by R, and return the number of bytes read.
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If we read off the end of the buffer, zero is returned,
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and nothing is stored in R.
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Note: The result is an int instead of a pointer to the next byte to be
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read to avoid const-vs-non-const problems. */
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static inline size_t
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read_sleb128_to_ll (const unsigned char *buf, const unsigned char *buf_end,
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long long *r)
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{
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const unsigned char *p = buf;
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unsigned int shift = 0;
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long long result = 0;
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unsigned char byte;
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while (1)
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{
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if (p >= buf_end)
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return 0;
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byte = *p++;
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result |= ((unsigned long long) (byte & 0x7f)) << shift;
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shift += 7;
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if ((byte & 0x80) == 0)
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break;
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}
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if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
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result |= -(((unsigned long long) 1) << shift);
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*r = result;
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return p - buf;
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}
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/* Return the number of bytes to read to skip past an LEB128 number in BUF.
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If the end isn't found before reaching BUF_END, return zero.
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Note: The result is an int instead of a pointer to the next byte to be
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read to avoid const-vs-non-const problems. */
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static inline size_t
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skip_leb128 (const unsigned char *buf, const unsigned char *buf_end)
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{
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const unsigned char *p = buf;
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unsigned char byte;
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while (1)
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{
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if (p == buf_end)
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return 0;
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byte = *p++;
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if ((byte & 0x80) == 0)
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return p - buf;
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}
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}
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#endif /* LEB128_H */
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