convert_integer_literal.cpp

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/*******************************************************************\
 
Module: C++ Language Conversion
 
Author: Daniel Kroening, kroening@kroening.com
 
\*******************************************************************/
 
 
#include "convert_integer_literal.h"
 
#include <cctype>
 
#include <util/arith_tools.h>
#include <util/config.h>
#include <util/std_expr.h>
#include <util/string2int.h>
 
exprt convert_integer_literal(const std::string &src)
{
  bool is_unsigned=false, is_imaginary=false;
  unsigned long_cnt=0;
  unsigned width_suffix=0;
  unsigned base=10;
 
  for(unsigned i=0; i<src.size(); i++)
  {
    char ch=src[i];
 
    if(ch=='u' || ch=='U')
      is_unsigned=true;
    else if(ch=='l' || ch=='L')
      long_cnt++;
    else if(ch=='i' || ch=='I')
    {
      // This can be "1i128" in MS mode,
      // and "10i" (imaginary) for GCC.
      // If it's followed by a number, we do MS mode.
      if((i+1)<src.size() && isdigit(src[i+1]))
        width_suffix=unsafe_string2unsigned(src.substr(i+1));
      else
        is_imaginary=true;
    }
    else if(ch=='j' || ch=='J')
      is_imaginary=true;
  }
 
  mp_integer value;
 
  if(src.size()>=2 && src[0]=='0' && tolower(src[1])=='x')
  {
    // hex; strip "0x"
    base=16;
    std::string without_prefix(src, 2, std::string::npos);
    value=string2integer(without_prefix, 16);
  }
  else if(src.size()>=2 && src[0]=='0' && tolower(src[1])=='b')
  {
    // binary; strip "0x"
    // see http://gcc.gnu.org/onlinedocs/gcc/Binary-constants.html
    base=2;
    std::string without_prefix(src, 2, std::string::npos);
    value=string2integer(without_prefix, 2);
  }
  else if(src.size()>=2 && src[0]=='0' && isdigit(src[1]))
  {
    // octal
    base=8;
    value=string2integer(src, 8);
  }
  else
  {
    // The default is base 10.
    value=string2integer(src, 10);
  }
 
  if(width_suffix!=0)
  {
    // this is a Microsoft extension
    irep_idt c_type;
 
    if(width_suffix<=config.ansi_c.int_width)
      c_type=is_unsigned?ID_unsigned_int:ID_signed_int;
    else if(width_suffix<=config.ansi_c.long_int_width)
      c_type=is_unsigned?ID_unsigned_long_int:ID_signed_long_int;
    else
      c_type=is_unsigned?ID_unsigned_long_long_int:ID_signed_long_long_int;
 
    bitvector_typet type(
      is_unsigned ? ID_unsignedbv : ID_signedbv, width_suffix);
    type.set(ID_C_c_type, c_type);
 
    exprt result=from_integer(value, type);
 
    return result;
  }
 
  mp_integer value_abs=value;
 
  if(value<0)
    value_abs.negate();
 
  bool is_hex_or_oct_or_bin=(base==8) || (base==16) || (base==2);
 
  #define FITS(width, signed) \
    ((signed?!is_unsigned:(is_unsigned || is_hex_or_oct_or_bin)) && \
    (power(2, signed?width-1:width)>value_abs))
 
  unsigned width;
  bool is_signed=false;
  irep_idt c_type;
 
  if(FITS(config.ansi_c.int_width, true) && long_cnt==0) // int
  {
    width=config.ansi_c.int_width;
    is_signed=true;
    c_type=ID_signed_int;
  }
  else if(FITS(config.ansi_c.int_width, false) && long_cnt==0) // unsigned int
  {
    width=config.ansi_c.int_width;
    is_signed=false;
    c_type=ID_unsigned_int;
  }
  else if(FITS(config.ansi_c.long_int_width, true) && long_cnt!=2) // long int
  {
    width=config.ansi_c.long_int_width;
    is_signed=true;
    c_type=ID_signed_long_int;
  }
  // unsigned long int
  else if(FITS(config.ansi_c.long_int_width, false) && long_cnt!=2)
  {
    width=config.ansi_c.long_int_width;
    is_signed=false;
    c_type=ID_unsigned_long_int;
  }
  else if(FITS(config.ansi_c.long_long_int_width, true)) // long long int
  {
    width=config.ansi_c.long_long_int_width;
    is_signed=true;
    c_type=ID_signed_long_long_int;
  }
  // unsigned long long int
  else if(FITS(config.ansi_c.long_long_int_width, false))
  {
    width=config.ansi_c.long_long_int_width;
    is_signed=false;
    c_type=ID_unsigned_long_long_int;
  }
  else
  {
    // Way too large. Should consider issuing a warning.
    width=config.ansi_c.long_long_int_width;
 
    if(is_unsigned)
    {
      is_signed=false;
      c_type=ID_unsigned_long_long_int;
    }
    else
      c_type=ID_signed_long_long_int;
  }
 
  bitvector_typet type(is_signed ? ID_signedbv : ID_unsignedbv, width);
  type.set(ID_C_c_type, c_type);
 
  exprt result;
 
  if(is_imaginary)
  {
    result = complex_exprt(
      from_integer(0, type), from_integer(value, type), complex_typet(type));
  }
  else
  {
    result=from_integer(value, type);
    result.set(ID_C_base, base);
  }
 
  return result;
}