xref: /illumos-gate/usr/src/lib/libdwarf/common/pro_encode_nm.c (revision 4d9fdb46)

/*

  Copyright (C) 2000,2004 Silicon Graphics, Inc.  All Rights Reserved.
  Portions Copyright 2011 David Anderson.  All Rights Reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of version 2.1 of the GNU Lesser General Public License
  as published by the Free Software Foundation.

  This program is distributed in the hope that it would be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

  Further, this software is distributed without any warranty that it is
  free of the rightful claim of any third person regarding infringement
  or the like.  Any license provided herein, whether implied or
  otherwise, applies only to this software file.  Patent licenses, if
  any, provided herein do not apply to combinations of this program with
  other software, or any other product whatsoever.

  You should have received a copy of the GNU Lesser General Public
  License along with this program; if not, write the Free Software
  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301,
  USA.

*/

#include "config.h"
#include "libdwarfdefs.h"
#include <string.h>
#include "dwarf.h"
#include "libdwarf.h"
#include "pro_encode_nm.h"

#define MORE_BYTES      0x80
#define DATA_MASK       0x7f
#define DIGIT_WIDTH     7
#define SIGN_BIT        0x40


/*  Encode val as a leb128. This encodes it as an unsigned
    number. */
/*  Return DW_DLV_ERROR or DW_DLV_OK.
    space to write leb number is provided by caller, with caller
    passing length.
    number of bytes used returned thru nbytes arg */
int
_dwarf_pro_encode_leb128_nm(Dwarf_Unsigned val, int *nbytes,
    char *space, int splen)
{
    char *a;
    char *end = space + splen;

    a = space;
    do {
        unsigned char uc;

        if (a >= end) {
            return DW_DLV_ERROR;
        }
        uc = val & DATA_MASK;
        val >>= DIGIT_WIDTH;
        if (val != 0) {
            uc |= MORE_BYTES;
        }
        *a = uc;
        a++;
    } while (val);
    *nbytes = (int)(a - space);
    return DW_DLV_OK;
}

/* return DW_DLV_ERROR or DW_DLV_OK.
** space to write leb number is provided by caller, with caller
** passing length.
** number of bytes used returned thru nbytes arg
** encodes a signed number.
*/
int
_dwarf_pro_encode_signed_leb128_nm(Dwarf_Signed value, int *nbytes,
    char *space, int splen)
{
    char *str;
    Dwarf_Signed sign = -(value < 0);
    int more = 1;
    char *end = space + splen;

    str = space;

    do {
        unsigned char byte = value & DATA_MASK;

        value >>= DIGIT_WIDTH;

        if (str >= end) {
            return DW_DLV_ERROR;
        }
        /*  Remaining chunks would just contain the sign bit, and this chunk
            has already captured at least one sign bit.  */
        if (value == sign && ((byte & SIGN_BIT) == (sign & SIGN_BIT))) {
            more = 0;
        } else {
            byte |= MORE_BYTES;
        }
        *str = byte;
        str++;
    } while (more);
    *nbytes = (int)(str - space);
    return DW_DLV_OK;
}