/*

** $Id: lmathlib.c $

** Standard mathematical library

** See Copyright Notice in lua.h

*/

#define lmathlib_c

#define LUA_LIB

#include "lprefix.h"

#include <float.h>

#include <limits.h>

#include <math.h>

#include <stdlib.h>

#include <time.h>

#include "lua.h"

#include "lauxlib.h"

#include "lualib.h"

#include "llimits.h"

#undef PI

#define PI  (l_mathop(3.141592653589793238462643383279502884))

static int math_abs (lua_State *L) {

  if (lua_isinteger(L, 1)) {

    lua_Integer n = lua_tointeger(L, 1);

    if (n < 0) n = (lua_Integer)(0u - (lua_Unsigned)n);

    lua_pushinteger(L, n);

  }

  else

    lua_pushnumber(L, l_mathop(fabs)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_sin (lua_State *L) {

  lua_pushnumber(L, l_mathop(sin)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_cos (lua_State *L) {

  lua_pushnumber(L, l_mathop(cos)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_tan (lua_State *L) {

  lua_pushnumber(L, l_mathop(tan)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_asin (lua_State *L) {

  lua_pushnumber(L, l_mathop(asin)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_acos (lua_State *L) {

  lua_pushnumber(L, l_mathop(acos)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_atan (lua_State *L) {

  lua_Number y = luaL_checknumber(L, 1);

  lua_Number x = luaL_optnumber(L, 2, 1);

  lua_pushnumber(L, l_mathop(atan2)(y, x));

  return 1;

}

static int math_toint (lua_State *L) {

  int valid;

  lua_Integer n = lua_tointegerx(L, 1, &valid);

  if (l_likely(valid))

    lua_pushinteger(L, n);

  else {

    luaL_checkany(L, 1);

    luaL_pushfail(L);  /* value is not convertible to integer */

  }

  return 1;

}

static void pushnumint (lua_State *L, lua_Number d) {

  lua_Integer n;

  if (lua_numbertointeger(d, &n))  /* does 'd' fit in an integer? */

    lua_pushinteger(L, n);  /* result is integer */

  else

    lua_pushnumber(L, d);  /* result is float */

}

static int math_floor (lua_State *L) {

  if (lua_isinteger(L, 1))

    lua_settop(L, 1);  /* integer is its own floor */

  else {

    lua_Number d = l_mathop(floor)(luaL_checknumber(L, 1));

    pushnumint(L, d);

  }

  return 1;

}

static int math_ceil (lua_State *L) {

  if (lua_isinteger(L, 1))

    lua_settop(L, 1);  /* integer is its own ceiling */

  else {

    lua_Number d = l_mathop(ceil)(luaL_checknumber(L, 1));

    pushnumint(L, d);

  }

  return 1;

}

static int math_fmod (lua_State *L) {

  if (lua_isinteger(L, 1) && lua_isinteger(L, 2)) {

    lua_Integer d = lua_tointeger(L, 2);

    if ((lua_Unsigned)d + 1u <= 1u) {  /* special cases: -1 or 0 */

      luaL_argcheck(L, d != 0, 2, "zero");

      lua_pushinteger(L, 0);  /* avoid overflow with 0x80000... / -1 */

    }

    else

      lua_pushinteger(L, lua_tointeger(L, 1) % d);

  }

  else

    lua_pushnumber(L, l_mathop(fmod)(luaL_checknumber(L, 1),

                                     luaL_checknumber(L, 2)));

  return 1;

}

/*

** next function does not use 'modf', avoiding problems with 'double*'

** (which is not compatible with 'float*') when lua_Number is not

** 'double'.

*/

static int math_modf (lua_State *L) {

  if (lua_isinteger(L ,1)) {

    lua_settop(L, 1);  /* number is its own integer part */

    lua_pushnumber(L, 0);  /* no fractional part */

  }

  else {

    lua_Number n = luaL_checknumber(L, 1);

    /* integer part (rounds toward zero) */

    lua_Number ip = (n < 0) ? l_mathop(ceil)(n) : l_mathop(floor)(n);

    pushnumint(L, ip);

    /* fractional part (test needed for inf/-inf) */

    lua_pushnumber(L, (n == ip) ? l_mathop(0.0) : (n - ip));

  }

  return 2;

}

static int math_sqrt (lua_State *L) {

  lua_pushnumber(L, l_mathop(sqrt)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_ult (lua_State *L) {

  lua_Integer a = luaL_checkinteger(L, 1);

  lua_Integer b = luaL_checkinteger(L, 2);

  lua_pushboolean(L, (lua_Unsigned)a < (lua_Unsigned)b);

  return 1;

}

static int math_log (lua_State *L) {

  lua_Number x = luaL_checknumber(L, 1);

  lua_Number res;

  if (lua_isnoneornil(L, 2))

    res = l_mathop(log)(x);

  else {

    lua_Number base = luaL_checknumber(L, 2);

#if !defined(LUA_USE_C89)

    if (base == l_mathop(2.0))

      res = l_mathop(log2)(x);

    else

#endif

    if (base == l_mathop(10.0))

      res = l_mathop(log10)(x);

    else

      res = l_mathop(log)(x)/l_mathop(log)(base);

  }

  lua_pushnumber(L, res);

  return 1;

}

static int math_exp (lua_State *L) {

  lua_pushnumber(L, l_mathop(exp)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_deg (lua_State *L) {

  lua_pushnumber(L, luaL_checknumber(L, 1) * (l_mathop(180.0) / PI));

  return 1;

}

static int math_rad (lua_State *L) {

  lua_pushnumber(L, luaL_checknumber(L, 1) * (PI / l_mathop(180.0)));

  return 1;

}

static int math_min (lua_State *L) {

  int n = lua_gettop(L);  /* number of arguments */

  int imin = 1;  /* index of current minimum value */

  int i;

  luaL_argcheck(L, n >= 1, 1, "value expected");

  for (i = 2; i <= n; i++) {

    if (lua_compare(L, i, imin, LUA_OPLT))

      imin = i;

  }

  lua_pushvalue(L, imin);

  return 1;

}

static int math_max (lua_State *L) {

  int n = lua_gettop(L);  /* number of arguments */

  int imax = 1;  /* index of current maximum value */

  int i;

  luaL_argcheck(L, n >= 1, 1, "value expected");

  for (i = 2; i <= n; i++) {

    if (lua_compare(L, imax, i, LUA_OPLT))

      imax = i;

  }

  lua_pushvalue(L, imax);

  return 1;

}

static int math_type (lua_State *L) {

  if (lua_type(L, 1) == LUA_TNUMBER)

    lua_pushstring(L, (lua_isinteger(L, 1)) ? "integer" : "float");

  else {

    luaL_checkany(L, 1);

    luaL_pushfail(L);

  }

  return 1;

}

/*

** {==================================================================

** Pseudo-Random Number Generator based on 'xoshiro256**'.

** ===================================================================

*/

/*

** This code uses lots of shifts. ANSI C does not allow shifts greater

** than or equal to the width of the type being shifted, so some shifts

** are written in convoluted ways to match that restriction. For

** preprocessor tests, it assumes a width of 32 bits, so the maximum

** shift there is 31 bits.

*/

/* number of binary digits in the mantissa of a float */

#define FIGS  l_floatatt(MANT_DIG)

#if FIGS > 64

/* there are only 64 random bits; use them all */

#undef FIGS

#define FIGS  64

#endif

/*

** LUA_RAND32 forces the use of 32-bit integers in the implementation

** of the PRN generator (mainly for testing).

*/

#if !defined(LUA_RAND32) && !defined(Rand64)

/* try to find an integer type with at least 64 bits */

#if ((ULONG_MAX >> 31) >> 31) >= 3

/* 'long' has at least 64 bits */

#define Rand64    unsigned long

#define SRand64   long

#elif !defined(LUA_USE_C89) && defined(LLONG_MAX)

/* there is a 'long long' type (which must have at least 64 bits) */

#define Rand64    unsigned long long

#define SRand64   long long

#elif ((LUA_MAXUNSIGNED >> 31) >> 31) >= 3

/* 'lua_Unsigned' has at least 64 bits */

#define Rand64    lua_Unsigned

#define SRand64   lua_Integer

#endif

#endif

#if defined(Rand64)  /* { */

/*

** Standard implementation, using 64-bit integers.

** If 'Rand64' has more than 64 bits, the extra bits do not interfere

** with the 64 initial bits, except in a right shift. Moreover, the

** final result has to discard the extra bits.

*/

/* avoid using extra bits when needed */

#define trim64(x) ((x) & 0xffffffffffffffffu)

/* rotate left 'x' by 'n' bits */

static Rand64 rotl (Rand64 x, int n) {

  return (x << n) | (trim64(x) >> (64 - n));

}

static Rand64 nextrand (Rand64 *state) {

  Rand64 state0 = state[0];

  Rand64 state1 = state[1];

  Rand64 state2 = state[2] ^ state0;

  Rand64 state3 = state[3] ^ state1;

  Rand64 res = rotl(state1 * 5, 7) * 9;

  state[0] = state0 ^ state3;

  state[1] = state1 ^ state2;

  state[2] = state2 ^ (state1 << 17);

  state[3] = rotl(state3, 45);

  return res;

}

/*

** Convert bits from a random integer into a float in the

** interval [0,1), getting the higher FIG bits from the

** random unsigned integer and converting that to a float.

** Some old Microsoft compilers cannot cast an unsigned long

** to a floating-point number, so we use a signed long as an

** intermediary. When lua_Number is float or double, the shift ensures

** that 'sx' is non negative; in that case, a good compiler will remove

** the correction.

*/

/* must throw out the extra (64 - FIGS) bits */

#define shift64_FIG (64 - FIGS)

/* 2^(-FIGS) == 2^-1 / 2^(FIGS-1) */

#define scaleFIG  (l_mathop(0.5) / ((Rand64)1 << (FIGS - 1)))

static lua_Number I2d (Rand64 x) {

  SRand64 sx = (SRand64)(trim64(x) >> shift64_FIG);

  lua_Number res = (lua_Number)(sx) * scaleFIG;

  if (sx < 0)

    res += l_mathop(1.0);  /* correct the two's complement if negative */

  lua_assert(0 <= res && res < 1);

  return res;

}

/* convert a 'Rand64' to a 'lua_Unsigned' */

#define I2UInt(x) ((lua_Unsigned)trim64(x))

/* convert a 'lua_Unsigned' to a 'Rand64' */

#define Int2I(x)  ((Rand64)(x))

#else /* no 'Rand64'   }{ */

/*

** Use two 32-bit integers to represent a 64-bit quantity.

*/

typedef struct Rand64 {

  l_uint32 h;  /* higher half */

  l_uint32 l;  /* lower half */

} Rand64;

/*

** If 'l_uint32' has more than 32 bits, the extra bits do not interfere

** with the 32 initial bits, except in a right shift and comparisons.

** Moreover, the final result has to discard the extra bits.

*/

/* avoid using extra bits when needed */

#define trim32(x) ((x) & 0xffffffffu)

/*

** basic operations on 'Rand64' values

*/

/* build a new Rand64 value */

static Rand64 packI (l_uint32 h, l_uint32 l) {

  Rand64 result;

  result.h = h;

  result.l = l;

  return result;

}

/* return i << n */

static Rand64 Ishl (Rand64 i, int n) {

  lua_assert(n > 0 && n < 32);

  return packI((i.h << n) | (trim32(i.l) >> (32 - n)), i.l << n);

}

/* i1 ^= i2 */

static void Ixor (Rand64 *i1, Rand64 i2) {

  i1->h ^= i2.h;

  i1->l ^= i2.l;

}

/* return i1 + i2 */

static Rand64 Iadd (Rand64 i1, Rand64 i2) {

  Rand64 result = packI(i1.h + i2.h, i1.l + i2.l);

  if (trim32(result.l) < trim32(i1.l))  /* carry? */

    result.h++;

  return result;

}

/* return i * 5 */

static Rand64 times5 (Rand64 i) {

  return Iadd(Ishl(i, 2), i);  /* i * 5 == (i << 2) + i */

}

/* return i * 9 */

static Rand64 times9 (Rand64 i) {

  return Iadd(Ishl(i, 3), i);  /* i * 9 == (i << 3) + i */

}

/* return 'i' rotated left 'n' bits */

static Rand64 rotl (Rand64 i, int n) {

  lua_assert(n > 0 && n < 32);

  return packI((i.h << n) | (trim32(i.l) >> (32 - n)),

               (trim32(i.h) >> (32 - n)) | (i.l << n));

}

/* for offsets larger than 32, rotate right by 64 - offset */

static Rand64 rotl1 (Rand64 i, int n) {

  lua_assert(n > 32 && n < 64);

  n = 64 - n;

  return packI((trim32(i.h) >> n) | (i.l << (32 - n)),

               (i.h << (32 - n)) | (trim32(i.l) >> n));

}

/*

** implementation of 'xoshiro256**' algorithm on 'Rand64' values

*/

static Rand64 nextrand (Rand64 *state) {

  Rand64 res = times9(rotl(times5(state[1]), 7));

  Rand64 t = Ishl(state[1], 17);

  Ixor(&state[2], state[0]);

  Ixor(&state[3], state[1]);

  Ixor(&state[1], state[2]);

  Ixor(&state[0], state[3]);

  Ixor(&state[2], t);

  state[3] = rotl1(state[3], 45);

  return res;

}

/*

** Converts a 'Rand64' into a float.

*/

/* an unsigned 1 with proper type */

#define UONE    ((l_uint32)1)

#if FIGS <= 32

/* 2^(-FIGS) */

#define scaleFIG       (l_mathop(0.5) / (UONE << (FIGS - 1)))

/*

** get up to 32 bits from higher half, shifting right to

** throw out the extra bits.

*/

static lua_Number I2d (Rand64 x) {

  lua_Number h = (lua_Number)(trim32(x.h) >> (32 - FIGS));

  return h * scaleFIG;

}

#else /* 32 < FIGS <= 64 */

/* 2^(-FIGS) = 1.0 / 2^30 / 2^3 / 2^(FIGS-33) */

#define scaleFIG  \

    (l_mathop(1.0) / (UONE << 30) / l_mathop(8.0) / (UONE << (FIGS - 33)))

/*

** use FIGS - 32 bits from lower half, throwing out the other

** (32 - (FIGS - 32)) = (64 - FIGS) bits

*/

#define shiftLOW  (64 - FIGS)

/*

** higher 32 bits go after those (FIGS - 32) bits: shiftHI = 2^(FIGS - 32)

*/

#define shiftHI   ((lua_Number)(UONE << (FIGS - 33)) * l_mathop(2.0))

static lua_Number I2d (Rand64 x) {

  lua_Number h = (lua_Number)trim32(x.h) * shiftHI;

  lua_Number l = (lua_Number)(trim32(x.l) >> shiftLOW);

  return (h + l) * scaleFIG;

}

#endif

/* convert a 'Rand64' to a 'lua_Unsigned' */

static lua_Unsigned I2UInt (Rand64 x) {

  return (((lua_Unsigned)trim32(x.h) << 31) << 1) | (lua_Unsigned)trim32(x.l);

}

/* convert a 'lua_Unsigned' to a 'Rand64' */

static Rand64 Int2I (lua_Unsigned n) {

  return packI((l_uint32)((n >> 31) >> 1), (l_uint32)n);

}

#endif  /* } */

/*

** A state uses four 'Rand64' values.

*/

typedef struct {

  Rand64 s[4];

} RanState;

/*

** Project the random integer 'ran' into the interval [0, n].

** Because 'ran' has 2^B possible values, the projection can only be

** uniform when the size of the interval is a power of 2 (exact

** division). So, to get a uniform projection into [0, n], we

** first compute 'lim', the smallest Mersenne number not smaller than

** 'n'. We then project 'ran' into the interval [0, lim].  If the result

** is inside [0, n], we are done. Otherwise, we try with another 'ran',

** until we have a result inside the interval.

*/

static lua_Unsigned project (lua_Unsigned ran, lua_Unsigned n,

                             RanState *state) {

  lua_Unsigned lim = n;  /* to compute the Mersenne number */

  int sh;  /* how much to spread bits to the right in 'lim' */

  /* spread '1' bits in 'lim' until it becomes a Mersenne number */

  for (sh = 1; (lim & (lim + 1)) != 0; sh *= 2)

    lim |= (lim >> sh);  /* spread '1's to the right */

  while ((ran &= lim) > n)  /* project 'ran' into [0..lim] and test */

    ran = I2UInt(nextrand(state->s));  /* not inside [0..n]? try again */

  return ran;

}

static int math_random (lua_State *L) {

  lua_Integer low, up;

  lua_Unsigned p;

  RanState *state = (RanState *)lua_touserdata(L, lua_upvalueindex(1));

  Rand64 rv = nextrand(state->s);  /* next pseudo-random value */

  switch (lua_gettop(L)) {  /* check number of arguments */

    case 0: {  /* no arguments */

      lua_pushnumber(L, I2d(rv));  /* float between 0 and 1 */

      return 1;

    }

    case 1: {  /* only upper limit */

      low = 1;

      up = luaL_checkinteger(L, 1);

      if (up == 0) {  /* single 0 as argument? */

        lua_pushinteger(L, l_castU2S(I2UInt(rv)));  /* full random integer */

        return 1;

      }

      break;

    }

    case 2: {  /* lower and upper limits */

      low = luaL_checkinteger(L, 1);

      up = luaL_checkinteger(L, 2);

      break;

    }

    default: return luaL_error(L, "wrong number of arguments");

  }

  /* random integer in the interval [low, up] */

  luaL_argcheck(L, low <= up, 1, "interval is empty");

  /* project random integer into the interval [0, up - low] */

  p = project(I2UInt(rv), l_castS2U(up) - l_castS2U(low), state);

  lua_pushinteger(L, l_castU2S(p + l_castS2U(low)));

  return 1;

}

static void setseed (lua_State *L, Rand64 *state,

                     lua_Unsigned n1, lua_Unsigned n2) {

  int i;

  state[0] = Int2I(n1);

  state[1] = Int2I(0xff);  /* avoid a zero state */

  state[2] = Int2I(n2);

  state[3] = Int2I(0);

  for (i = 0; i < 16; i++)

    nextrand(state);  /* discard initial values to "spread" seed */

  lua_pushinteger(L, l_castU2S(n1));

  lua_pushinteger(L, l_castU2S(n2));

}

static int math_randomseed (lua_State *L) {

  RanState *state = (RanState *)lua_touserdata(L, lua_upvalueindex(1));

  lua_Unsigned n1, n2;

  if (lua_isnone(L, 1)) {

    n1 = luaL_makeseed(L);  /* "random" seed */

    n2 = I2UInt(nextrand(state->s));  /* in case seed is not that random... */

  }

  else {

    n1 = l_castS2U(luaL_checkinteger(L, 1));

    n2 = l_castS2U(luaL_optinteger(L, 2, 0));

  }

  setseed(L, state->s, n1, n2);

  return 2;  /* return seeds */

}

static const luaL_Reg randfuncs[] = {

  {"random", math_random},

  {"randomseed", math_randomseed},

  {NULL, NULL}

};

/*

** Register the random functions and initialize their state.

*/

static void setrandfunc (lua_State *L) {

  RanState *state = (RanState *)lua_newuserdatauv(L, sizeof(RanState), 0);

  setseed(L, state->s, luaL_makeseed(L), 0);  /* initialize with random seed */

  lua_pop(L, 2);  /* remove pushed seeds */

  luaL_setfuncs(L, randfuncs, 1);

}

/* }================================================================== */

/*

** {==================================================================

** Deprecated functions (for compatibility only)

** ===================================================================

*/

#if defined(LUA_COMPAT_MATHLIB)

static int math_cosh (lua_State *L) {

  lua_pushnumber(L, l_mathop(cosh)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_sinh (lua_State *L) {

  lua_pushnumber(L, l_mathop(sinh)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_tanh (lua_State *L) {

  lua_pushnumber(L, l_mathop(tanh)(luaL_checknumber(L, 1)));

  return 1;

}

static int math_pow (lua_State *L) {

  lua_Number x = luaL_checknumber(L, 1);

  lua_Number y = luaL_checknumber(L, 2);

  lua_pushnumber(L, l_mathop(pow)(x, y));

  return 1;

}

static int math_frexp (lua_State *L) {

  int e;

  lua_pushnumber(L, l_mathop(frexp)(luaL_checknumber(L, 1), &e));

  lua_pushinteger(L, e);

  return 2;

}

static int math_ldexp (lua_State *L) {

  lua_Number x = luaL_checknumber(L, 1);

  int ep = (int)luaL_checkinteger(L, 2);

  lua_pushnumber(L, l_mathop(ldexp)(x, ep));

  return 1;

}

static int math_log10 (lua_State *L) {

  lua_pushnumber(L, l_mathop(log10)(luaL_checknumber(L, 1)));

  return 1;

}

#endif

/* }================================================================== */

static const luaL_Reg mathlib[] = {

  {"abs",   math_abs},

  {"acos",  math_acos},

  {"asin",  math_asin},

  {"atan",  math_atan},

  {"ceil",  math_ceil},

  {"cos",   math_cos},

  {"deg",   math_deg},

  {"exp",   math_exp},

  {"tointeger", math_toint},

  {"floor", math_floor},

  {"fmod",   math_fmod},

  {"ult",   math_ult},

  {"log",   math_log},

  {"max",   math_max},

  {"min",   math_min},

  {"modf",   math_modf},

  {"rad",   math_rad},

  {"sin",   math_sin},

  {"sqrt",  math_sqrt},

  {"tan",   math_tan},

  {"type", math_type},

#if defined(LUA_COMPAT_MATHLIB)

  {"atan2", math_atan},

  {"cosh",   math_cosh},

  {"sinh",   math_sinh},

  {"tanh",   math_tanh},

  {"pow",   math_pow},

  {"frexp", math_frexp},

  {"ldexp", math_ldexp},

  {"log10", math_log10},

#endif

  /* placeholders */

  {"random", NULL},

  {"randomseed", NULL},

  {"pi", NULL},

  {"huge", NULL},

  {"maxinteger", NULL},

  {"mininteger", NULL},

  {NULL, NULL}

};

/*

** Open math library

*/

LUAMOD_API int luaopen_math (lua_State *L) {

  luaL_newlib(L, mathlib);

  lua_pushnumber(L, PI);

  lua_setfield(L, -2, "pi");

  lua_pushnumber(L, (lua_Number)HUGE_VAL);

  lua_setfield(L, -2, "huge");

  lua_pushinteger(L, LUA_MAXINTEGER);

  lua_setfield(L, -2, "maxinteger");

  lua_pushinteger(L, LUA_MININTEGER);

  lua_setfield(L, -2, "mininteger");

  setrandfunc(L);

  return 1;

}