text: /*
  ** $Id: lobject.c,v 2.55 2011/11/30 19:30:16 roberto Exp $
  ** Some generic functions over Lua objects
  ** See Copyright Notice in lua.h
  */
  
  #include <stdarg.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #define lobject_c
  #define LUA_CORE
  
  #include "lua.h"
  
  #include "lctype.h"
  #include "ldebug.h"
  #include "ldo.h"
  #include "lmem.h"
  #include "lobject.h"
  #include "lstate.h"
  #include "lstring.h"
  #include "lvm.h"
  
  
  
  LUAI_DDEF const TValue luaO_nilobject_ = {NILCONSTANT};
  
  
  /*
  ** converts an integer to a "floating point byte", represented as
  ** (eeeeexxx), where the real value is (1xxx) * 2^(eeeee - 1) if
  ** eeeee != 0 and (xxx) otherwise.
  */
  int luaO_int2fb (unsigned int x) {
    int e = 0;  /* exponent */
    if (x < 8) return x;
    while (x >= 0x10) {
      x = (x+1) >> 1;
      e++;
    }
    return ((e+1) << 3) | (cast_int(x) - 8);
  }
  
  
  /* converts back */
  int luaO_fb2int (int x) {
    int e = (x >> 3) & 0x1f;
    if (e == 0) return x;
    else return ((x & 7) + 8) << (e - 1);
  }
  
  
  int luaO_ceillog2 (unsigned int x) {
    static const lu_byte log_2[256] = {
      0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
      6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
      7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
      7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
      8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
      8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
      8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
      8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8
    };
    int l = 0;
    x--;
    while (x >= 256) { l += 8; x >>= 8; }
    return l + log_2[x];
  }
  
  
  lua_Number luaO_arith (int op, lua_Number v1, lua_Number v2) {
    switch (op) {
      case LUA_OPADD: return luai_numadd(NULL, v1, v2);
      case LUA_OPSUB: return luai_numsub(NULL, v1, v2);
      case LUA_OPMUL: return luai_nummul(NULL, v1, v2);
      case LUA_OPDIV: return luai_numdiv(NULL, v1, v2);
      case LUA_OPMOD: return luai_nummod(NULL, v1, v2);
      case LUA_OPPOW: return luai_numpow(NULL, v1, v2);
      case LUA_OPUNM: return luai_numunm(NULL, v1);
      default: lua_assert(0); return 0;
    }
  }
  
  
  int luaO_hexavalue (int c) {
    if (lisdigit(c)) return c - '0';
    else return ltolower(c) - 'a' + 10;
  }
  
  
  #if !defined(lua_strx2number)
  
  #include <math.h>
  
  
  static int isneg (const char **s) {
    if (**s == '-') { (*s)++; return 1; }
    else if (**s == '+') (*s)++;
    return 0;
  }
  
  
  static lua_Number readhexa (const char **s, lua_Number r, int *count) {
    for (; lisxdigit(cast_uchar(**s)); (*s)++) {  /* read integer part */
      r = (r * 16.0) + cast_num(luaO_hexavalue(cast_uchar(**s)));
      (*count)++;
    }
    return r;
  }
  
  
  /*
  ** convert an hexadecimal numeric string to a number, following
  ** C99 specification for 'strtod'
  */
  static lua_Number lua_strx2number (const char *s, char **endptr) {
    lua_Number r = 0.0;
    int e = 0, i = 0;
    int neg = 0;  /* 1 if number is negative */
    *endptr = cast(char *, s);  /* nothing is valid yet */
    while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
    neg = isneg(&s);  /* check signal */
    if (!(*s == '0' && (*(s + 1) == 'x' || *(s + 1) == 'X')))  /* check '0x' */
      return 0.0;  /* invalid format (no '0x') */
    s += 2;  /* skip '0x' */
    r = readhexa(&s, r, &i);  /* read integer part */
    if (*s == '.') {
      s++;  /* skip dot */
      r = readhexa(&s, r, &e);  /* read fractional part */
    }
    if (i == 0 && e == 0)
      return 0.0;  /* invalid format (no digit) */
    e *= -4;  /* each fractional digit divides value by 2^-4 */
    *endptr = cast(char *, s);  /* valid up to here */
    if (*s == 'p' || *s == 'P') {  /* exponent part? */
      int exp1 = 0;
      int neg1;
      s++;  /* skip 'p' */
      neg1 = isneg(&s);  /* signal */
      if (!lisdigit(cast_uchar(*s)))
        goto ret;  /* must have at least one digit */
      while (lisdigit(cast_uchar(*s)))  /* read exponent */
        exp1 = exp1 * 10 + *(s++) - '0';
      if (neg1) exp1 = -exp1;
      e += exp1;
    }
    *endptr = cast(char *, s);  /* valid up to here */
   ret:
    if (neg) r = -r;
    return ldexp(r, e);
  }
  
  #endif
  
  
  int luaO_str2d (const char *s, size_t len, lua_Number *result) {
    char *endptr;
    if (strpbrk(s, "nN"))  /* reject 'inf' and 'nan' */
      return 0;
    else if (strpbrk(s, "xX"))  /* hexa? */
      *result = lua_strx2number(s, &endptr);
    else
      *result = lua_str2number(s, &endptr);
    if (endptr == s) return 0;  /* nothing recognized */
    while (lisspace(cast_uchar(*endptr))) endptr++;
    return (endptr == s + len);  /* OK if no trailing characters */
  }
  
  
  
  static void pushstr (lua_State *L, const char *str, size_t l) {
    setsvalue2s(L, L->top, luaS_newlstr(L, str, l));
    incr_top(L);
  }
  
  
  /* this function handles only `%d', `%c', %f, %p, and `%s' formats */
  const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
    int n = 0;
    for (;;) {
      const char *e = strchr(fmt, '%');
      if (e == NULL) break;
      setsvalue2s(L, L->top, luaS_newlstr(L, fmt, e-fmt));
      incr_top(L);
      switch (*(e+1)) {
        case 's': {
          const char *s = va_arg(argp, char *);
          if (s == NULL) s = "(null)";
          pushstr(L, s, strlen(s));
          break;
        }
        case 'c': {
          char buff;
          buff = cast(char, va_arg(argp, int));
          pushstr(L, &buff, 1);
          break;
        }
        case 'd': {
          setnvalue(L->top, cast_num(va_arg(argp, int)));
          incr_top(L);
          break;
        }
        case 'f': {
          setnvalue(L->top, cast_num(va_arg(argp, l_uacNumber)));
          incr_top(L);
          break;
        }
        case 'p': {
          char buff[4*sizeof(void *) + 8]; /* should be enough space for a `%p' */
          int l = sprintf(buff, "%p", va_arg(argp, void *));
          pushstr(L, buff, l);
          break;
        }
        case '%': {
          pushstr(L, "%", 1);
          break;
        }
        default: {
          luaG_runerror(L,
              "invalid option " LUA_QL("%%%c") " to " LUA_QL("lua_pushfstring"),
              *(e + 1));
        }
      }
      n += 2;
      fmt = e+2;
    }
    pushstr(L, fmt, strlen(fmt));
    if (n > 0) luaV_concat(L, n + 1);
    return svalue(L->top - 1);
  }
  
  
  const char *luaO_pushfstring (lua_State *L, const char *fmt, ...) {
    const char *msg;
    va_list argp;
    va_start(argp, fmt);
    msg = luaO_pushvfstring(L, fmt, argp);
    va_end(argp);
    return msg;
  }
  
  
  /* number of chars of a literal string without the ending \0 */
  #define LL(x)	(sizeof(x)/sizeof(char) - 1)
  
  #define RETS	"..."
  #define PRE	"[string \""
  #define POS	"\"]"
  
  #define addstr(a,b,l)	( memcpy(a,b,(l) * sizeof(char)), a += (l) )
  
  void luaO_chunkid (char *out, const char *source, size_t bufflen) {
    size_t l = strlen(source);
    if (*source == '=') {  /* 'literal' source */
      if (l <= bufflen)  /* small enough? */
        memcpy(out, source + 1, l * sizeof(char));
      else {  /* truncate it */
        addstr(out, source + 1, bufflen - 1);
        *out = '\0';
      }
    }
    else if (*source == '@') {  /* file name */
      if (l <= bufflen)  /* small enough? */
        memcpy(out, source + 1, l * sizeof(char));
      else {  /* add '...' before rest of name */
        addstr(out, RETS, LL(RETS));
        bufflen -= LL(RETS);
        memcpy(out, source + 1 + l - bufflen, bufflen * sizeof(char));
      }
    }
    else {  /* string; format as [string "source"] */
      const char *nl = strchr(source, '\n');  /* find first new line (if any) */
      addstr(out, PRE, LL(PRE));  /* add prefix */
      bufflen -= LL(PRE RETS POS) + 1;  /* save space for prefix+suffix+'\0' */
      if (l < bufflen && nl == NULL) {  /* small one-line source? */
        addstr(out, source, l);  /* keep it */
      }
      else {
        if (nl != NULL) l = nl - source;  /* stop at first newline */
        if (l > bufflen) l = bufflen;
        addstr(out, source, l);
        addstr(out, RETS, LL(RETS));
      }
      memcpy(out, POS, (LL(POS) + 1) * sizeof(char));
    }
  }
  
  