text: /*
   * ULP error checking tool for math functions.
   *
   * Copyright (c) 2019, Arm Limited.
   * SPDX-License-Identifier: MIT
   */
  
  #include <ctype.h>
  #include <fenv.h>
  #include <float.h>
  #include <math.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include "mathlib.h"
  
  /* Don't depend on mpfr by default.  */
  #ifndef USE_MPFR
  # define USE_MPFR 0
  #endif
  #if USE_MPFR
  # include <mpfr.h>
  #endif
  
  #ifndef WANT_VMATH
  /* Enable the build of vector math code.  */
  # define WANT_VMATH 1
  #endif
  
  static inline uint64_t
  asuint64 (double f)
  {
    union
    {
      double f;
      uint64_t i;
    } u = {f};
    return u.i;
  }
  
  static inline double
  asdouble (uint64_t i)
  {
    union
    {
      uint64_t i;
      double f;
    } u = {i};
    return u.f;
  }
  
  static inline uint32_t
  asuint (float f)
  {
    union
    {
      float f;
      uint32_t i;
    } u = {f};
    return u.i;
  }
  
  static inline float
  asfloat (uint32_t i)
  {
    union
    {
      uint32_t i;
      float f;
    } u = {i};
    return u.f;
  }
  
  static uint64_t seed = 0x0123456789abcdef;
  static uint64_t
  rand64 (void)
  {
    seed = 6364136223846793005ull * seed + 1;
    return seed ^ (seed >> 32);
  }
  
  /* Uniform random in [0,n].  */
  static uint64_t
  randn (uint64_t n)
  {
    uint64_t r, m;
  
    if (n == 0)
      return 0;
    n++;
    if (n == 0)
      return rand64 ();
    for (;;)
      {
        r = rand64 ();
        m = r % n;
        if (r - m <= -n)
  	return m;
      }
  }
  
  struct gen
  {
    uint64_t start;
    uint64_t len;
    uint64_t start2;
    uint64_t len2;
    uint64_t off;
    uint64_t step;
    uint64_t cnt;
  };
  
  struct args_f1
  {
    float x;
  };
  
  struct args_f2
  {
    float x;
    float x2;
  };
  
  struct args_d1
  {
    double x;
  };
  
  struct args_d2
  {
    double x;
    double x2;
  };
  
  /* result = y + tail*2^ulpexp.  */
  struct ret_f
  {
    float y;
    double tail;
    int ulpexp;
    int ex;
    int ex_may;
  };
  
  struct ret_d
  {
    double y;
    double tail;
    int ulpexp;
    int ex;
    int ex_may;
  };
  
  static inline uint64_t
  next1 (struct gen *g)
  {
    /* For single argument use randomized incremental steps,
       that produce dense sampling without collisions and allow
       testing all inputs in a range.  */
    uint64_t r = g->start + g->off;
    g->off += g->step + randn (g->step / 2);
    if (g->off > g->len)
      g->off -= g->len; /* hack.  */
    return r;
  }
  
  static inline uint64_t
  next2 (uint64_t *x2, struct gen *g)
  {
    /* For two arguments use uniform random sampling.  */
    uint64_t r = g->start + randn (g->len);
    *x2 = g->start2 + randn (g->len2);
    return r;
  }
  
  static struct args_f1
  next_f1 (void *g)
  {
    return (struct args_f1){asfloat (next1 (g))};
  }
  
  static struct args_f2
  next_f2 (void *g)
  {
    uint64_t x2;
    uint64_t x = next2 (&x2, g);
    return (struct args_f2){asfloat (x), asfloat (x2)};
  }
  
  static struct args_d1
  next_d1 (void *g)
  {
    return (struct args_d1){asdouble (next1 (g))};
  }
  
  static struct args_d2
  next_d2 (void *g)
  {
    uint64_t x2;
    uint64_t x = next2 (&x2, g);
    return (struct args_d2){asdouble (x), asdouble (x2)};
  }
  
  struct conf
  {
    int r;
    int rc;
    int quiet;
    int mpfr;
    int fenv;
    unsigned long long n;
    double softlim;
    double errlim;
  };
  
  /* A bit of a hack: call vector functions twice with the same
     input in lane 0 but a different value in other lanes: once
     with an in-range value and then with a special case value.  */
  static int secondcall;
  
  /* Wrappers for vector functions.  */
  #if __aarch64__ && WANT_VMATH
  typedef __f32x4_t v_float;
  typedef __f64x2_t v_double;
  static const float fv[2] = {1.0f, -INFINITY};
  static const double dv[2] = {1.0, -INFINITY};
  static inline v_float argf(float x) { return (v_float){x,x,x,fv[secondcall]}; }
  static inline v_double argd(double x) { return (v_double){x,dv[secondcall]}; }
  
  static float v_sinf(float x) { return __v_sinf(argf(x))[0]; }
  static float v_cosf(float x) { return __v_cosf(argf(x))[0]; }
  static float v_expf_1u(float x) { return __v_expf_1u(argf(x))[0]; }
  static float v_expf(float x) { return __v_expf(argf(x))[0]; }
  static float v_exp2f_1u(float x) { return __v_exp2f_1u(argf(x))[0]; }
  static float v_exp2f(float x) { return __v_exp2f(argf(x))[0]; }
  static float v_logf(float x) { return __v_logf(argf(x))[0]; }
  static float v_powf(float x, float y) { return __v_powf(argf(x),argf(y))[0]; }
  static double v_sin(double x) { return __v_sin(argd(x))[0]; }
  static double v_cos(double x) { return __v_cos(argd(x))[0]; }
  static double v_exp(double x) { return __v_exp(argd(x))[0]; }
  static double v_log(double x) { return __v_log(argd(x))[0]; }
  #ifdef __vpcs
  static float vn_sinf(float x) { return __vn_sinf(argf(x))[0]; }
  static float vn_cosf(float x) { return __vn_cosf(argf(x))[0]; }
  static float vn_expf_1u(float x) { return __vn_expf_1u(argf(x))[0]; }
  static float vn_expf(float x) { return __vn_expf(argf(x))[0]; }
  static float vn_exp2f_1u(float x) { return __vn_exp2f_1u(argf(x))[0]; }
  static float vn_exp2f(float x) { return __vn_exp2f(argf(x))[0]; }
  static float vn_logf(float x) { return __vn_logf(argf(x))[0]; }
  static float vn_powf(float x, float y) { return __vn_powf(argf(x),argf(y))[0]; }
  static double vn_sin(double x) { return __vn_sin(argd(x))[0]; }
  static double vn_cos(double x) { return __vn_cos(argd(x))[0]; }
  static double vn_exp(double x) { return __vn_exp(argd(x))[0]; }
  static double vn_log(double x) { return __vn_log(argd(x))[0]; }
  static float Z_sinf(float x) { return _ZGVnN4v_sinf(argf(x))[0]; }
  static float Z_cosf(float x) { return _ZGVnN4v_cosf(argf(x))[0]; }
  static float Z_expf(float x) { return _ZGVnN4v_expf(argf(x))[0]; }
  static float Z_exp2f(float x) { return _ZGVnN4v_exp2f(argf(x))[0]; }
  static float Z_logf(float x) { return _ZGVnN4v_logf(argf(x))[0]; }
  static float Z_powf(float x, float y) { return _ZGVnN4vv_powf(argf(x),argf(y))[0]; }
  static double Z_sin(double x) { return _ZGVnN2v_sin(argd(x))[0]; }
  static double Z_cos(double x) { return _ZGVnN2v_cos(argd(x))[0]; }
  static double Z_exp(double x) { return _ZGVnN2v_exp(argd(x))[0]; }
  static double Z_log(double x) { return _ZGVnN2v_log(argd(x))[0]; }
  #endif
  #endif
  
  struct fun
  {
    const char *name;
    int arity;
    int singleprec;
    int twice;
    union
    {
      float (*f1) (float);
      float (*f2) (float, float);
      double (*d1) (double);
      double (*d2) (double, double);
    } fun;
    union
    {
      double (*f1) (double);
      double (*f2) (double, double);
      long double (*d1) (long double);
      long double (*d2) (long double, long double);
    } fun_long;
  #if USE_MPFR
    union
    {
      int (*f1) (mpfr_t, const mpfr_t, mpfr_rnd_t);
      int (*f2) (mpfr_t, const mpfr_t, const mpfr_t, mpfr_rnd_t);
      int (*d1) (mpfr_t, const mpfr_t, mpfr_rnd_t);
      int (*d2) (mpfr_t, const mpfr_t, const mpfr_t, mpfr_rnd_t);
    } fun_mpfr;
  #endif
  };
  
  static const struct fun fun[] = {
  #if USE_MPFR
  # define F(x, x_wrap, x_long, x_mpfr, a, s, t, twice) \
    {#x, a, s, twice, {.t = x_wrap}, {.t = x_long}, {.t = x_mpfr}},
  #else
  # define F(x, x_wrap, x_long, x_mpfr, a, s, t, twice) \
    {#x, a, s, twice, {.t = x_wrap}, {.t = x_long}},
  #endif
  #define F1(x) F (x##f, x##f, x, mpfr_##x, 1, 1, f1, 0)
  #define F2(x) F (x##f, x##f, x, mpfr_##x, 2, 1, f2, 0)
  #define D1(x) F (x, x, x##l, mpfr_##x, 1, 0, d1, 0)
  #define D2(x) F (x, x, x##l, mpfr_##x, 2, 0, d2, 0)
   F1 (sin)
   F1 (cos)
   F1 (exp)
   F1 (exp2)
   F1 (log)
   F1 (log2)
   F2 (pow)
   D1 (exp)
   D1 (exp2)
   D1 (log)
   D1 (log2)
   D2 (pow)
  #if WANT_VMATH
   F (__s_sinf, __s_sinf, sin, mpfr_sin, 1, 1, f1, 0)
   F (__s_cosf, __s_cosf, cos, mpfr_cos, 1, 1, f1, 0)
   F (__s_expf_1u, __s_expf_1u, exp, mpfr_exp, 1, 1, f1, 0)
   F (__s_expf, __s_expf, exp, mpfr_exp, 1, 1, f1, 0)
   F (__s_exp2f_1u, __s_exp2f_1u, exp2, mpfr_exp2, 1, 1, f1, 0)
   F (__s_exp2f, __s_exp2f, exp2, mpfr_exp2, 1, 1, f1, 0)
   F (__s_powf, __s_powf, pow, mpfr_pow, 2, 1, f2, 0)
   F (__s_logf, __s_logf, log, mpfr_log, 1, 1, f1, 0)
   F (__s_sin, __s_sin, sinl, mpfr_sin, 1, 0, d1, 0)
   F (__s_cos, __s_cos, cosl, mpfr_cos, 1, 0, d1, 0)
   F (__s_exp, __s_exp, expl, mpfr_exp, 1, 0, d1, 0)
   F (__s_log, __s_log, logl, mpfr_log, 1, 0, d1, 0)
  #if __aarch64__
   F (__v_sinf, v_sinf, sin, mpfr_sin, 1, 1, f1, 1)
   F (__v_cosf, v_cosf, cos, mpfr_cos, 1, 1, f1, 1)
   F (__v_expf_1u, v_expf_1u, exp, mpfr_exp, 1, 1, f1, 1)
   F (__v_expf, v_expf, exp, mpfr_exp, 1, 1, f1, 1)
   F (__v_exp2f_1u, v_exp2f_1u, exp2, mpfr_exp2, 1, 1, f1, 1)
   F (__v_exp2f, v_exp2f, exp2, mpfr_exp2, 1, 1, f1, 1)
   F (__v_logf, v_logf, log, mpfr_log, 1, 1, f1, 1)
   F (__v_powf, v_powf, pow, mpfr_pow, 2, 1, f2, 1)
   F (__v_sin, v_sin, sinl, mpfr_sin, 1, 0, d1, 1)
   F (__v_cos, v_cos, cosl, mpfr_cos, 1, 0, d1, 1)
   F (__v_exp, v_exp, expl, mpfr_exp, 1, 0, d1, 1)
   F (__v_log, v_log, logl, mpfr_log, 1, 0, d1, 1)
  #ifdef __vpcs
   F (__vn_sinf, vn_sinf, sin, mpfr_sin, 1, 1, f1, 1)
   F (__vn_cosf, vn_cosf, cos, mpfr_cos, 1, 1, f1, 1)
   F (__vn_expf_1u, vn_expf_1u, exp, mpfr_exp, 1, 1, f1, 1)
   F (__vn_expf, vn_expf, exp, mpfr_exp, 1, 1, f1, 1)
   F (__vn_exp2f_1u, vn_exp2f_1u, exp2, mpfr_exp2, 1, 1, f1, 1)
   F (__vn_exp2f, vn_exp2f, exp2, mpfr_exp2, 1, 1, f1, 1)
   F (__vn_logf, vn_logf, log, mpfr_log, 1, 1, f1, 1)
   F (__vn_powf, vn_powf, pow, mpfr_pow, 2, 1, f2, 1)
   F (__vn_sin, vn_sin, sinl, mpfr_sin, 1, 0, d1, 1)
   F (__vn_cos, vn_cos, cosl, mpfr_cos, 1, 0, d1, 1)
   F (__vn_exp, vn_exp, expl, mpfr_exp, 1, 0, d1, 1)
   F (__vn_log, vn_log, logl, mpfr_log, 1, 0, d1, 1)
   F (_ZGVnN4v_sinf, Z_sinf, sin, mpfr_sin, 1, 1, f1, 1)
   F (_ZGVnN4v_cosf, Z_cosf, cos, mpfr_cos, 1, 1, f1, 1)
   F (_ZGVnN4v_expf, Z_expf, exp, mpfr_exp, 1, 1, f1, 1)
   F (_ZGVnN4v_exp2f, Z_exp2f, exp2, mpfr_exp2, 1, 1, f1, 1)
   F (_ZGVnN4v_logf, Z_logf, log, mpfr_log, 1, 1, f1, 1)
   F (_ZGVnN4vv_powf, Z_powf, pow, mpfr_pow, 2, 1, f2, 1)
   F (_ZGVnN2v_sin, Z_sin, sinl, mpfr_sin, 1, 0, d1, 1)
   F (_ZGVnN2v_cos, Z_cos, cosl, mpfr_cos, 1, 0, d1, 1)
   F (_ZGVnN2v_exp, Z_exp, expl, mpfr_exp, 1, 0, d1, 1)
   F (_ZGVnN2v_log, Z_log, logl, mpfr_log, 1, 0, d1, 1)
  #endif
  #endif
  #endif
  #undef F
  #undef F1
  #undef F2
  #undef D1
  #undef D2
   {0}};
  
  /* Boilerplate for generic calls.  */
  
  static inline int
  ulpscale_f (float x)
  {
    int e = asuint (x) >> 23 & 0xff;
    if (!e)
      e++;
    return e - 0x7f - 23;
  }
  static inline int
  ulpscale_d (double x)
  {
    int e = asuint64 (x) >> 52 & 0x7ff;
    if (!e)
      e++;
    return e - 0x3ff - 52;
  }
  static inline float
  call_f1 (const struct fun *f, struct args_f1 a)
  {
    return f->fun.f1 (a.x);
  }
  static inline float
  call_f2 (const struct fun *f, struct args_f2 a)
  {
    return f->fun.f2 (a.x, a.x2);
  }
  
  static inline double
  call_d1 (const struct fun *f, struct args_d1 a)
  {
    return f->fun.d1 (a.x);
  }
  static inline double
  call_d2 (const struct fun *f, struct args_d2 a)
  {
    return f->fun.d2 (a.x, a.x2);
  }
  static inline double
  call_long_f1 (const struct fun *f, struct args_f1 a)
  {
    return f->fun_long.f1 (a.x);
  }
  static inline double
  call_long_f2 (const struct fun *f, struct args_f2 a)
  {
    return f->fun_long.f2 (a.x, a.x2);
  }
  static inline long double
  call_long_d1 (const struct fun *f, struct args_d1 a)
  {
    return f->fun_long.d1 (a.x);
  }
  static inline long double
  call_long_d2 (const struct fun *f, struct args_d2 a)
  {
    return f->fun_long.d2 (a.x, a.x2);
  }
  static inline void
  printcall_f1 (const struct fun *f, struct args_f1 a)
  {
    printf ("%s(%a)", f->name, a.x);
  }
  static inline void
  printcall_f2 (const struct fun *f, struct args_f2 a)
  {
    printf ("%s(%a, %a)", f->name, a.x, a.x2);
  }
  static inline void
  printcall_d1 (const struct fun *f, struct args_d1 a)
  {
    printf ("%s(%a)", f->name, a.x);
  }
  static inline void
  printcall_d2 (const struct fun *f, struct args_d2 a)
  {
    printf ("%s(%a, %a)", f->name, a.x, a.x2);
  }
  static inline void
  printgen_f1 (const struct fun *f, struct gen *gen)
  {
    printf ("%s in [%a;%a]", f->name, asfloat (gen->start),
  	  asfloat (gen->start + gen->len));
  }
  static inline void
  printgen_f2 (const struct fun *f, struct gen *gen)
  {
    printf ("%s in [%a;%a] x [%a;%a]", f->name, asfloat (gen->start),
  	  asfloat (gen->start + gen->len), asfloat (gen->start2),
  	  asfloat (gen->start2 + gen->len2));
  }
  static inline void
  printgen_d1 (const struct fun *f, struct gen *gen)
  {
    printf ("%s in [%a;%a]", f->name, asdouble (gen->start),
  	  asdouble (gen->start + gen->len));
  }
  static inline void
  printgen_d2 (const struct fun *f, struct gen *gen)
  {
    printf ("%s in [%a;%a] x [%a;%a]", f->name, asdouble (gen->start),
  	  asdouble (gen->start + gen->len), asdouble (gen->start2),
  	  asdouble (gen->start2 + gen->len2));
  }
  
  #define reduce_f1(a, f, op) (f (a.x))
  #define reduce_f2(a, f, op) (f (a.x) op f (a.x2))
  #define reduce_d1(a, f, op) (f (a.x))
  #define reduce_d2(a, f, op) (f (a.x) op f (a.x2))
  
  #ifndef IEEE_754_2008_SNAN
  # define IEEE_754_2008_SNAN 1
  #endif
  static inline int
  issignaling_f (float x)
  {
    uint32_t ix = asuint (x);
    if (!IEEE_754_2008_SNAN)
      return (ix & 0x7fc00000) == 0x7fc00000;
    return 2 * (ix ^ 0x00400000) > 2u * 0x7fc00000;
  }
  static inline int
  issignaling_d (double x)
  {
    uint64_t ix = asuint64 (x);
    if (!IEEE_754_2008_SNAN)
      return (ix & 0x7ff8000000000000) == 0x7ff8000000000000;
    return 2 * (ix ^ 0x0008000000000000) > 2 * 0x7ff8000000000000ULL;
  }
  
  #if USE_MPFR
  static mpfr_rnd_t
  rmap (int r)
  {
    switch (r)
      {
      case FE_TONEAREST:
        return MPFR_RNDN;
      case FE_TOWARDZERO:
        return MPFR_RNDZ;
      case FE_UPWARD:
        return MPFR_RNDU;
      case FE_DOWNWARD:
        return MPFR_RNDD;
      }
    return -1;
  }
  
  #define prec_mpfr_f 50
  #define prec_mpfr_d 80
  #define prec_f 24
  #define prec_d 53
  #define emin_f -148
  #define emin_d -1073
  #define emax_f 128
  #define emax_d 1024
  static inline int
  call_mpfr_f1 (mpfr_t y, const struct fun *f, struct args_f1 a, mpfr_rnd_t r)
  {
    MPFR_DECL_INIT (x, prec_f);
    mpfr_set_flt (x, a.x, MPFR_RNDN);
    return f->fun_mpfr.f1 (y, x, r);
  }
  static inline int
  call_mpfr_f2 (mpfr_t y, const struct fun *f, struct args_f2 a, mpfr_rnd_t r)
  {
    MPFR_DECL_INIT (x, prec_f);
    MPFR_DECL_INIT (x2, prec_f);
    mpfr_set_flt (x, a.x, MPFR_RNDN);
    mpfr_set_flt (x2, a.x2, MPFR_RNDN);
    return f->fun_mpfr.f2 (y, x, x2, r);
  }
  static inline int
  call_mpfr_d1 (mpfr_t y, const struct fun *f, struct args_d1 a, mpfr_rnd_t r)
  {
    MPFR_DECL_INIT (x, prec_d);
    mpfr_set_d (x, a.x, MPFR_RNDN);
    return f->fun_mpfr.d1 (y, x, r);
  }
  static inline int
  call_mpfr_d2 (mpfr_t y, const struct fun *f, struct args_d2 a, mpfr_rnd_t r)
  {
    MPFR_DECL_INIT (x, prec_d);
    MPFR_DECL_INIT (x2, prec_d);
    mpfr_set_d (x, a.x, MPFR_RNDN);
    mpfr_set_d (x2, a.x2, MPFR_RNDN);
    return f->fun_mpfr.d2 (y, x, x2, r);
  }
  #endif
  
  #define float_f float
  #define double_f double
  #define copysign_f copysignf
  #define nextafter_f nextafterf
  #define fabs_f fabsf
  #define asuint_f asuint
  #define asfloat_f asfloat
  #define scalbn_f scalbnf
  #define lscalbn_f scalbn
  #define halfinf_f 0x1p127f
  #define min_normal_f 0x1p-126f
  
  #define float_d double
  #define double_d long double
  #define copysign_d copysign
  #define nextafter_d nextafter
  #define fabs_d fabs
  #define asuint_d asuint64
  #define asfloat_d asdouble
  #define scalbn_d scalbn
  #define lscalbn_d scalbnl
  #define halfinf_d 0x1p1023
  #define min_normal_d 0x1p-1022
  
  #define NEW_RT
  #define RT(x) x##_f
  #define T(x) x##_f1
  #include "ulp.h"
  #undef T
  #define T(x) x##_f2
  #include "ulp.h"
  #undef T
  #undef RT
  
  #define NEW_RT
  #define RT(x) x##_d
  #define T(x) x##_d1
  #include "ulp.h"
  #undef T
  #define T(x) x##_d2
  #include "ulp.h"
  #undef T
  #undef RT
  
  static void
  usage (void)
  {
    puts ("./ulp [-q] [-m] [-f] [-r nudz] [-l soft-ulplimit] [-e ulplimit] func "
  	"lo [hi [x lo2 hi2] [count]]");
    puts ("Compares func against a higher precision implementation in [lo; hi].");
    puts ("-q: quiet.");
    puts ("-m: use mpfr even if faster method is available.");
    puts ("-f: disable fenv testing (rounding modes and exceptions).");
    puts ("Supported func:");
    for (const struct fun *f = fun; f->name; f++)
      printf ("\t%s\n", f->name);
    exit (1);
  }
  
  static int
  cmp (const struct fun *f, struct gen *gen, const struct conf *conf)
  {
    int r = 1;
    if (f->arity == 1 && f->singleprec)
      r = cmp_f1 (f, gen, conf);
    else if (f->arity == 2 && f->singleprec)
      r = cmp_f2 (f, gen, conf);
    else if (f->arity == 1 && !f->singleprec)
      r = cmp_d1 (f, gen, conf);
    else if (f->arity == 2 && !f->singleprec)
      r = cmp_d2 (f, gen, conf);
    else
      usage ();
    return r;
  }
  
  static uint64_t
  getnum (const char *s, int singleprec)
  {
    //	int i;
    uint64_t sign = 0;
    //	char buf[12];
  
    if (s[0] == '+')
      s++;
    else if (s[0] == '-')
      {
        sign = singleprec ? 1ULL << 31 : 1ULL << 63;
        s++;
      }
    /* 0xXXXX is treated as bit representation, '-' flips the sign bit.  */
    if (s[0] == '0' && tolower (s[1]) == 'x' && strchr (s, 'p') == 0)
      return sign ^ strtoull (s, 0, 0);
    //	/* SNaN, QNaN, NaN, Inf.  */
    //	for (i=0; s[i] && i < sizeof buf; i++)
    //		buf[i] = tolower(s[i]);
    //	buf[i] = 0;
    //	if (strcmp(buf, "snan") == 0)
    //		return sign | (singleprec ? 0x7fa00000 : 0x7ff4000000000000);
    //	if (strcmp(buf, "qnan") == 0 || strcmp(buf, "nan") == 0)
    //		return sign | (singleprec ? 0x7fc00000 : 0x7ff8000000000000);
    //	if (strcmp(buf, "inf") == 0 || strcmp(buf, "infinity") == 0)
    //		return sign | (singleprec ? 0x7f800000 : 0x7ff0000000000000);
    /* Otherwise assume it's a floating-point literal.  */
    return sign
  	 | (singleprec ? asuint (strtof (s, 0)) : asuint64 (strtod (s, 0)));
  }
  
  static void
  parsegen (struct gen *g, int argc, char *argv[], const struct fun *f)
  {
    int singleprec = f->singleprec;
    int arity = f->arity;
    uint64_t a, b, a2, b2, n;
    if (argc < 1)
      usage ();
    b = a = getnum (argv[0], singleprec);
    n = 0;
    if (argc > 1 && strcmp (argv[1], "x") == 0)
      {
        argc -= 2;
        argv += 2;
      }
    else if (argc > 1)
      {
        b = getnum (argv[1], singleprec);
        if (argc > 2 && strcmp (argv[2], "x") == 0)
  	{
  	  argc -= 3;
  	  argv += 3;
  	}
      }
    b2 = a2 = getnum (argv[0], singleprec);
    if (argc > 1)
      b2 = getnum (argv[1], singleprec);
    if (argc > 2)
      n = strtoull (argv[2], 0, 0);
    if (argc > 3)
      usage ();
    //printf("ab %lx %lx ab2 %lx %lx n %lu\n", a, b, a2, b2, n);
    if (arity == 1)
      {
        g->start = a;
        g->len = b - a;
        if (n - 1 > b - a)
  	n = b - a + 1;
        g->off = 0;
        g->step = n ? (g->len + 1) / n : 1;
        g->start2 = g->len2 = 0;
        g->cnt = n;
      }
    else if (arity == 2)
      {
        g->start = a;
        g->len = b - a;
        g->off = g->step = 0;
        g->start2 = a2;
        g->len2 = b2 - a2;
        g->cnt = n;
      }
    else
      usage ();
  }
  
  int
  main (int argc, char *argv[])
  {
    const struct fun *f;
    struct gen gen;
    struct conf conf;
    conf.rc = 'n';
    conf.quiet = 0;
    conf.mpfr = 0;
    conf.fenv = 1;
    conf.softlim = 0;
    conf.errlim = INFINITY;
    for (;;)
      {
        argc--;
        argv++;
        if (argc < 1)
  	usage ();
        if (argv[0][0] != '-')
  	break;
        switch (argv[0][1])
  	{
  	case 'e':
  	  argc--;
  	  argv++;
  	  if (argc < 1)
  	    usage ();
  	  conf.errlim = strtod (argv[0], 0);
  	  break;
  	case 'f':
  	  conf.fenv = 0;
  	  break;
  	case 'l':
  	  argc--;
  	  argv++;
  	  if (argc < 1)
  	    usage ();
  	  conf.softlim = strtod (argv[0], 0);
  	  break;
  	case 'm':
  	  conf.mpfr = 1;
  	  break;
  	case 'q':
  	  conf.quiet = 1;
  	  break;
  	case 'r':
  	  conf.rc = argv[0][2];
  	  if (!conf.rc)
  	    {
  	      argc--;
  	      argv++;
  	      if (argc < 1)
  		usage ();
  	      conf.rc = argv[0][0];
  	    }
  	  break;
  	default:
  	  usage ();
  	}
      }
    switch (conf.rc)
      {
      case 'n':
        conf.r = FE_TONEAREST;
        break;
      case 'u':
        conf.r = FE_UPWARD;
        break;
      case 'd':
        conf.r = FE_DOWNWARD;
        break;
      case 'z':
        conf.r = FE_TOWARDZERO;
        break;
      default:
        usage ();
      }
    for (f = fun; f->name; f++)
      if (strcmp (argv[0], f->name) == 0)
        break;
    if (!f->name)
      usage ();
    if (!f->singleprec && LDBL_MANT_DIG == DBL_MANT_DIG)
      conf.mpfr = 1; /* Use mpfr if long double has no extra precision.  */
    if (!USE_MPFR && conf.mpfr)
      {
        puts ("mpfr is not available.");
        return 0;
      }
    argc--;
    argv++;
    parsegen (&gen, argc, argv, f);
    conf.n = gen.cnt;
    return cmp (f, &gen, &conf);
  }
  