wsutil/sign_ext.h

   1 /** @file
   2  *
   3  * Wireshark - Network traffic analyzer
   4  * By Gerald Combs <gerald@wireshark.org>
   5  * Copyright 1998 Gerald Combs
   6  *
   7  * SPDX-License-Identifier: GPL-2.0-or-later
   8  */
   9
  10 #ifndef __WSUTIL_SIGN_EXT_H__
  11 #define __WSUTIL_SIGN_EXT_H__
  12
  13 #include <inttypes.h>
  14
  15 #include <glib.h>
  16
  17 #include <wsutil/ws_assert.h>
  18
  19 /* sign extension routines */
  20
  21 static inline uint32_t
  22 ws_sign_ext32(uint32_t val, int no_of_bits)
  23 {
  24         ws_assert (no_of_bits >= 0 && no_of_bits <= 32);
  25
  26         if ((no_of_bits == 0) || (no_of_bits == 32))
  27                 return val;
  28
  29         /*
  30          * Don't shift signed values left; that's not valid in C99, at
  31          * least, if the value is negative or if the shift count is
  32          * the number of bits in the value - 1, and we might get
  33          * compile-time or run-time complaints about that.
  34          */
  35         if (val & (1U << (no_of_bits-1)))
  36                 val |= (0xFFFFFFFFU << no_of_bits);
  37
  38         return val;
  39 }
  40
  41 static inline uint64_t
  42 ws_sign_ext64(uint64_t val, int no_of_bits)
  43 {
  44         ws_assert (no_of_bits >= 0 && no_of_bits <= 64);
  45
  46         if ((no_of_bits == 0) || (no_of_bits == 64))
  47                 return val;
  48
  49         /*
  50          * Don't shift signed values left; that's not valid in C99, at
  51          * least, if the value is negative or if the shift count is
  52          * the number of bits in the value - 1, and we might get
  53          * compile-time or run-time complaints about that.
  54          */
  55         if (val & (UINT64_C(1) << (no_of_bits-1)))
  56                 val |= (UINT64_C(0xFFFFFFFFFFFFFFFF) << no_of_bits);
  57
  58         return val;
  59 }
  60
  61 /*
  62 static inline uint64_t
  63 ws_sign_ext64(uint64_t val, int no_of_bits)
  64 {
  65         int64_t sval = (val << (64 - no_of_bits));
  66
  67         return (uint64_t) (sval >> (64 - no_of_bits));
  68 }
  69 */
  70
  71 #endif /* __WSUTIL_SIGN_EXT_H__ */