mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-24 07:31:32 +00:00
137 lines
3.7 KiB
C
137 lines
3.7 KiB
C
/* Utilities for reading leb128 values.
|
|
Copyright (C) 2012-2017 Free Software Foundation, Inc.
|
|
|
|
This file is part of the libiberty library.
|
|
Libiberty is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2 of the License, or (at your option) any later version.
|
|
|
|
Libiberty is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with libiberty; see the file COPYING.LIB. If not, write
|
|
to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
|
|
Boston, MA 02110-1301, USA. */
|
|
|
|
/* The functions defined here can be speed critical.
|
|
Since they are all pretty small we keep things simple and just define
|
|
them all as "static inline".
|
|
|
|
WARNING: This file is used by GDB which is stuck at C90. :-(
|
|
Though it can use stdint.h, inttypes.h.
|
|
Therefore if you want to add support for "long long" you need
|
|
to wrap it in #ifdef CC_HAS_LONG_LONG. */
|
|
|
|
#ifndef LEB128_H
|
|
#define LEB128_H
|
|
|
|
/* Get a definition for inline. */
|
|
#include "ansidecl.h"
|
|
|
|
/* Get a definition for NULL, size_t. */
|
|
#include <stddef.h>
|
|
|
|
#ifdef HAVE_STDINT_H
|
|
#include <stdint.h>
|
|
#endif
|
|
#ifdef HAVE_INTTYPES_H
|
|
#include <inttypes.h>
|
|
#endif
|
|
|
|
/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
|
|
by R, and return the number of bytes read.
|
|
If we read off the end of the buffer, zero is returned,
|
|
and nothing is stored in R.
|
|
|
|
Note: The result is an int instead of a pointer to the next byte to be
|
|
read to avoid const-vs-non-const problems. */
|
|
|
|
static inline size_t
|
|
read_uleb128_to_uint64 (const unsigned char *buf, const unsigned char *buf_end,
|
|
uint64_t *r)
|
|
{
|
|
const unsigned char *p = buf;
|
|
unsigned int shift = 0;
|
|
uint64_t result = 0;
|
|
unsigned char byte;
|
|
|
|
while (1)
|
|
{
|
|
if (p >= buf_end)
|
|
return 0;
|
|
|
|
byte = *p++;
|
|
result |= ((uint64_t) (byte & 0x7f)) << shift;
|
|
if ((byte & 0x80) == 0)
|
|
break;
|
|
shift += 7;
|
|
}
|
|
|
|
*r = result;
|
|
return p - buf;
|
|
}
|
|
|
|
/* Decode the signed LEB128 constant at BUF into the variable pointed to
|
|
by R, and return the number of bytes read.
|
|
If we read off the end of the buffer, zero is returned,
|
|
and nothing is stored in R.
|
|
|
|
Note: The result is an int instead of a pointer to the next byte to be
|
|
read to avoid const-vs-non-const problems. */
|
|
|
|
static inline size_t
|
|
read_sleb128_to_int64 (const unsigned char *buf, const unsigned char *buf_end,
|
|
int64_t *r)
|
|
{
|
|
const unsigned char *p = buf;
|
|
unsigned int shift = 0;
|
|
int64_t result = 0;
|
|
unsigned char byte;
|
|
|
|
while (1)
|
|
{
|
|
if (p >= buf_end)
|
|
return 0;
|
|
|
|
byte = *p++;
|
|
result |= ((uint64_t) (byte & 0x7f)) << shift;
|
|
shift += 7;
|
|
if ((byte & 0x80) == 0)
|
|
break;
|
|
}
|
|
if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
|
|
result |= -(((uint64_t) 1) << shift);
|
|
|
|
*r = result;
|
|
return p - buf;
|
|
}
|
|
|
|
/* Return the number of bytes to read to skip past an LEB128 number in BUF.
|
|
If the end isn't found before reaching BUF_END, return zero.
|
|
|
|
Note: The result is an int instead of a pointer to the next byte to be
|
|
read to avoid const-vs-non-const problems. */
|
|
|
|
static inline size_t
|
|
skip_leb128 (const unsigned char *buf, const unsigned char *buf_end)
|
|
{
|
|
const unsigned char *p = buf;
|
|
unsigned char byte;
|
|
|
|
while (1)
|
|
{
|
|
if (p == buf_end)
|
|
return 0;
|
|
|
|
byte = *p++;
|
|
if ((byte & 0x80) == 0)
|
|
return p - buf;
|
|
}
|
|
}
|
|
|
|
#endif /* LEB128_H */
|