usr/src/lib/libdwarf/common/pro_encode_nm.c

   1 /*
   2
   3   Copyright (C) 2000,2004 Silicon Graphics, Inc.  All Rights Reserved.
   4
   5   This program is free software; you can redistribute it and/or modify it
   6   under the terms of version 2.1 of the GNU Lesser General Public License
   7   as published by the Free Software Foundation.
   8
   9   This program is distributed in the hope that it would be useful, but
  10   WITHOUT ANY WARRANTY; without even the implied warranty of
  11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12
  13   Further, this software is distributed without any warranty that it is
  14   free of the rightful claim of any third person regarding infringement
  15   or the like.  Any license provided herein, whether implied or
  16   otherwise, applies only to this software file.  Patent licenses, if
  17   any, provided herein do not apply to combinations of this program with
  18   other software, or any other product whatsoever.
  19
  20   You should have received a copy of the GNU Lesser General Public
  21   License along with this program; if not, write the Free Software
  22   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301,
  23   USA.
  24
  25   Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
  26   Mountain View, CA 94043, or:
  27
  28   http://www.sgi.com
  29
  30   For further information regarding this notice, see:
  31
  32   http://oss.sgi.com/projects/GenInfo/NoticeExplan
  33
  34 */
  35
  36
  37
  38 #include "config.h"
  39 #include "libdwarfdefs.h"
  40 #include <string.h>
  41 #include "pro_incl.h"
  42
  43 #define MORE_BYTES      0x80
  44 #define DATA_MASK       0x7f
  45 #define DIGIT_WIDTH     7
  46 #define SIGN_BIT        0x40
  47
  48
  49 /*-------------------------------------------------------------
  50         Encode val as a leb128. This encodes it as an unsigned
  51         number.
  52 ---------------------------------------------------------------*/
  53 /* return DW_DLV_ERROR or DW_DLV_OK.
  54 ** space to write leb number is provided by caller, with caller
  55 ** passing length.
  56 ** number of bytes used returned thru nbytes arg
  57 */
  58 int
  59 _dwarf_pro_encode_leb128_nm(Dwarf_Unsigned val, int *nbytes,
  60                             char *space, int splen)
  61 {
  62     char *a;
  63     char *end = space + splen;
  64
  65     a = space;
  66     do {
  67         unsigned char uc;
  68
  69         if (a >= end) {
  70             return DW_DLV_ERROR;
  71         }
  72         uc = val & DATA_MASK;
  73         val >>= DIGIT_WIDTH;
  74         if (val != 0) {
  75             uc |= MORE_BYTES;
  76         }
  77         *a = uc;
  78         a++;
  79     } while (val);
  80     *nbytes = a - space;
  81     return DW_DLV_OK;
  82 }
  83
  84 /* return DW_DLV_ERROR or DW_DLV_OK.
  85 ** space to write leb number is provided by caller, with caller
  86 ** passing length.
  87 ** number of bytes used returned thru nbytes arg
  88 ** encodes a signed number.
  89 */
  90 int
  91 _dwarf_pro_encode_signed_leb128_nm(Dwarf_Signed value, int *nbytes,
  92                                    char *space, int splen)
  93 {
  94     char *str;
  95     Dwarf_Signed sign = -(value < 0);
  96     int more = 1;
  97     char *end = space + splen;
  98
  99     str = space;
 100
 101     do {
 102         unsigned char byte = value & DATA_MASK;
 103
 104         value >>= DIGIT_WIDTH;
 105
 106         if (str >= end) {
 107             return DW_DLV_ERROR;
 108         }
 109         /*
 110          * Remaining chunks would just contain the sign bit, and this chunk
 111          * has already captured at least one sign bit.
 112          */
 113         if (value == sign && ((byte & SIGN_BIT) == (sign & SIGN_BIT))) {
 114             more = 0;
 115         } else {
 116             byte |= MORE_BYTES;
 117         }
 118         *str = byte;
 119         str++;
 120     } while (more);
 121     *nbytes = str - space;
 122     return DW_DLV_OK;
 123 }