text: /***********************************************************************/
  /*                                                                     */
  /*                           Objective Caml                            */
  /*                                                                     */
  /*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
  /*                                                                     */
  /*  Copyright 2002 Institut National de Recherche en Informatique et   */
  /*  en Automatique.  All rights reserved.  This file is distributed    */
  /*  under the terms of the GNU Library General Public License, with    */
  /*  the special exception on linking described in file ../LICENSE.     */
  /*                                                                     */
  /***********************************************************************/
  
  /* $Id: int64_emul.h 10217 2010-03-29 11:29:24Z xleroy $ */
  
  /* Software emulation of 64-bit integer arithmetic, for C compilers
     that do not support it.  */
  
  #ifndef CAML_INT64_EMUL_H
  #define CAML_INT64_EMUL_H
  
  #include <math.h>
  
  #ifdef ARCH_BIG_ENDIAN
  #define I64_literal(hi,lo) { hi, lo }
  #else
  #define I64_literal(hi,lo) { lo, hi }
  #endif
  
  /* Unsigned comparison */
  static int I64_ucompare(uint64 x, uint64 y)
  {
    if (x.h > y.h) return 1;
    if (x.h < y.h) return -1;
    if (x.l > y.l) return 1;
    if (x.l < y.l) return -1;
    return 0;
  }
  
  #define I64_ult(x, y) (I64_ucompare(x, y) < 0)
  
  /* Signed comparison */
  static int I64_compare(int64 x, int64 y)
  {
    if ((int32)x.h > (int32)y.h) return 1;
    if ((int32)x.h < (int32)y.h) return -1;
    if (x.l > y.l) return 1;
    if (x.l < y.l) return -1;
    return 0;
  }
  
  /* Negation */
  static int64 I64_neg(int64 x)
  {
    int64 res;
    res.l = -x.l;
    res.h = ~x.h;
    if (res.l == 0) res.h++;
    return res;
  }
  
  /* Addition */
  static int64 I64_add(int64 x, int64 y)
  {
    int64 res;
    res.l = x.l + y.l;
    res.h = x.h + y.h;
    if (res.l < x.l) res.h++;
    return res;
  }
  
  /* Subtraction */
  static int64 I64_sub(int64 x, int64 y)
  {
    int64 res;
    res.l = x.l - y.l;
    res.h = x.h - y.h;
    if (x.l < y.l) res.h--;
    return res;
  }
  
  /* Multiplication */
  static int64 I64_mul(int64 x, int64 y)
  {
    int64 res;
    uint32 prod00 = (x.l & 0xFFFF) * (y.l & 0xFFFF);
    uint32 prod10 = (x.l >> 16) * (y.l & 0xFFFF);
    uint32 prod01 = (x.l & 0xFFFF) * (y.l >> 16);
    uint32 prod11 = (x.l >> 16) * (y.l >> 16);
    res.l = prod00;
    res.h = prod11 + (prod01 >> 16) + (prod10 >> 16);
    prod01 = prod01 << 16; res.l += prod01; if (res.l < prod01) res.h++;
    prod10 = prod10 << 16; res.l += prod10; if (res.l < prod10) res.h++;
    res.h += x.l * y.h + x.h * y.l;
    return res;
  }
  
  #define I64_is_zero(x) (((x).l | (x).h) == 0)
  #define I64_is_negative(x) ((int32) (x).h < 0)
  #define I64_is_min_int(x) ((x).l == 0 && (x).h == 0x80000000U)
  #define I64_is_minus_one(x) (((x).l & (x).h) == 0xFFFFFFFFU)
  
  /* Bitwise operations */
  static int64 I64_and(int64 x, int64 y)
  {
    int64 res;
    res.l = x.l & y.l;
    res.h = x.h & y.h;
    return res;
  }
  
  static int64 I64_or(int64 x, int64 y)
  {
    int64 res;
    res.l = x.l | y.l;
    res.h = x.h | y.h;
    return res;
  }
  
  static int64 I64_xor(int64 x, int64 y)
  {
    int64 res;
    res.l = x.l ^ y.l;
    res.h = x.h ^ y.h;
    return res;
  }
  
  /* Shifts */
  static int64 I64_lsl(int64 x, int s)
  {
    int64 res;
    s = s & 63;
    if (s == 0) return x;
    if (s < 32) {
      res.l = x.l << s;
      res.h = (x.h << s) | (x.l >> (32 - s));
    } else {
      res.l = 0;
      res.h = x.l << (s - 32);
    }
    return res;
  }
  
  static int64 I64_lsr(int64 x, int s)
  {
    int64 res;
    s = s & 63;
    if (s == 0) return x;
    if (s < 32) {
      res.l = (x.l >> s) | (x.h << (32 - s));
      res.h = x.h >> s;
    } else {
      res.l = x.h >> (s - 32);
      res.h = 0;
    }
    return res;
  }
  
  static int64 I64_asr(int64 x, int s)
  {
    int64 res;
    s = s & 63;
    if (s == 0) return x;
    if (s < 32) {
      res.l = (x.l >> s) | (x.h << (32 - s));
      res.h = (int32) x.h >> s;
    } else {
      res.l = (int32) x.h >> (s - 32);
      res.h = (int32) x.h >> 31;
    }
    return res;
  }
  
  /* Division and modulus */
  
  #define I64_SHL1(x) x.h = (x.h << 1) | (x.l >> 31); x.l <<= 1
  #define I64_SHR1(x) x.l = (x.l >> 1) | (x.h << 31); x.h >>= 1
  
  static void I64_udivmod(uint64 modulus, uint64 divisor,
                          uint64 * quo, uint64 * mod)
  {
    int64 quotient, mask;
    int cmp;
  
    quotient.h = 0; quotient.l = 0;
    mask.h = 0; mask.l = 1;
    while ((int32) divisor.h >= 0) {
      cmp = I64_ucompare(divisor, modulus);
      I64_SHL1(divisor);
      I64_SHL1(mask);
      if (cmp >= 0) break;
    }
    while (mask.l | mask.h) {
      if (I64_ucompare(modulus, divisor) >= 0) {
        quotient.h |= mask.h; quotient.l |= mask.l;
        modulus = I64_sub(modulus, divisor);
      }
      I64_SHR1(mask);
      I64_SHR1(divisor);
    }
    *quo = quotient;
    *mod = modulus;
  }
  
  static int64 I64_div(int64 x, int64 y)
  {
    int64 q, r;
    int32 sign;
  
    sign = x.h ^ y.h;
    if ((int32) x.h < 0) x = I64_neg(x);
    if ((int32) y.h < 0) y = I64_neg(y);
    I64_udivmod(x, y, &q, &r);
    if (sign < 0) q = I64_neg(q);
    return q;
  }
  
  static int64 I64_mod(int64 x, int64 y)
  {
    int64 q, r;
    int32 sign;
  
    sign = x.h;
    if ((int32) x.h < 0) x = I64_neg(x);
    if ((int32) y.h < 0) y = I64_neg(y);
    I64_udivmod(x, y, &q, &r);
    if (sign < 0) r = I64_neg(r);
    return r;
  }
  
  /* Coercions */
  
  static int64 I64_of_int32(int32 x)
  {
    int64 res;
    res.l = x;
    res.h = x >> 31;
    return res;
  }
  
  #define I64_to_int32(x) ((int32) (x).l)
  
  /* Note: we assume sizeof(intnat) = 4 here, which is true otherwise
     autoconfiguration would have selected native 64-bit integers */
  #define I64_of_intnat I64_of_int32
  #define I64_to_intnat I64_to_int32
  
  static double I64_to_double(int64 x)
  {
    double res;
    int32 sign = x.h;
    if (sign < 0) x = I64_neg(x);
    res = ldexp((double) x.h, 32) + x.l;
    if (sign < 0) res = -res;
    return res;
  }
  
  static int64 I64_of_double(double f)
  {
    int64 res;
    double frac, integ;
    int neg;
  
    neg = (f < 0);
    f = fabs(f);
    frac = modf(ldexp(f, -32), &integ);
    res.h = (uint32) integ;
    res.l = (uint32) ldexp(frac, 32);
    if (neg) res = I64_neg(res);
    return res;
  }
  
  #endif /* CAML_INT64_EMUL_H */
  