Hi. This is a slightly modified version of my previous patch.
ref: http://gcc.gnu.org/ml/gcc-patches/2012-05/msg00962.html The only change is to make the result of the functions an int instead of a const pointer. This lets them be used in places where the code is using non-const pointers without having to apply ugly casts. Ok to check in? 2012-05-17 Doug Evans <d...@google.com> * leb128.h: New file. Index: leb128.h =================================================================== RCS file: leb128.h diff -N leb128.h --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ leb128.h 17 May 2012 18:23:29 -0000 @@ -0,0 +1,130 @@ +/* Utilities for reading leb128 values. + Copyright (C) 2012 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". */ + +#ifndef LEB128_H +#define LEB128_H + +#include "ansidecl.h" + +/* Get a definition for NULL. */ +#include <stdio.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 int +read_uleb128 (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 int +read_sleb128 (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 int +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 & 128) == 0) + return p - buf; + } +} + +#endif /* LEB128_H */
