/* Copyright (C) 2001-2021 Artifex Software, Inc.

   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or

   implied.

   This software is distributed under license and may not be copied,

   modified or distributed except as expressly authorized under the terms

   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact

   Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,

   CA 94945, U.S.A., +1(415)492-9861, for further information.

*/

/* Mathematical operators */

#include "math_.h"

#include "ghost.h"

#include "gxfarith.h"

#include "oper.h"

#include "store.h"

/*

 * Many of the procedures in this file are public only so they can be

 * called from the FunctionType 4 interpreter (zfunc4.c).

 */

/*

 * Define the current state of random number generator for operators.  We

 * have to implement this ourselves because the Unix rand doesn't provide

 * anything equivalent to rrand.  Note that the value always lies in the

 * range [0..0x7ffffffe], even if longs are longer than 32 bits.

 *

 * The state must be public so that context switching can save and

 * restore it.  (Even though the Red Book doesn't mention this,

 * we verified with Adobe that this is the case.)

 */

#define zrand_state (i_ctx_p->rand_state)

/* Initialize the random number generator. */

const long rand_state_initial = 1;

/****** NOTE: none of these operators currently ******/

/****** check for floating over- or underflow.  ******/

/* <num> sqrt <real> */

int

zsqrt(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double num;

    int code = real_param(op, &num);

    if (code < 0)

        return code;

    if (num < 0.0)

        return_error(gs_error_rangecheck);

    make_real(op, sqrt(num));

    return 0;

}

/* <num> arccos <real> */

static int

zarccos(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double num, result;

    int code = real_param(op, &num);

    if (code < 0)

        return code;

    result = acos(num) * radians_to_degrees;

    make_real(op, result);

    return 0;

}

/* <num> arcsin <real> */

static int

zarcsin(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double num, result;

    int code = real_param(op, &num);

    if (code < 0)

        return code;

    result = asin(num) * radians_to_degrees;

    make_real(op, result);

    return 0;

}

/* <num> <denom> atan <real> */

int

zatan(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double args[2];

    double result;

    int code = num_params(op, 2, args);

    if (code < 0)

        return code;

    code = gs_atan2_degrees(args[0], args[1], &result);

    if (code < 0)

        return code;

    make_real(op - 1, result);

    pop(1);

    return 0;

}

/* <num> cos <real> */

int

zcos(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double angle;

    int code = real_param(op, &angle);

    if (code < 0)

        return code;

    make_real(op, gs_cos_degrees(angle));

    return 0;

}

/* <num> sin <real> */

int

zsin(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double angle;

    int code = real_param(op, &angle);

    if (code < 0)

        return code;

    make_real(op, gs_sin_degrees(angle));

    return 0;

}

/* <base> <exponent> exp <real> */

int

zexp(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double args[2];

    double result;

    double ipart;

    int code = num_params(op, 2, args);

    if (code < 0)

        return code;

    if (args[0] == 0.0 && args[1] < 0)

        return_error(gs_error_undefinedresult);

    if (args[0] < 0.0 && modf(args[1], &ipart) != 0.0)

        return_error(gs_error_undefinedresult);

    if (args[0] == 0.0 && args[1] == 0.0)

        result = 1.0;    /* match Adobe; can't rely on C library */

    else

        result = pow(args[0], args[1]);

#ifdef HAVE_ISINF

    if (isinf((op - 1)->value.realval))

        return_error(gs_error_undefinedresult);

#endif

    make_real(op - 1, result);

    pop(1);

    return 0;

}

/* <posnum> ln <real> */

int

zln(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double num;

    int code = real_param(op, &num);

    if (code < 0)

        return code;

    if (num <= 0.0)

        return_error(gs_error_rangecheck);

    make_real(op, log(num));

    return 0;

}

/* <posnum> log <real> */

int

zlog(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    double num;

    int code = real_param(op, &num);

    if (code < 0)

        return code;

    if (num <= 0.0)

        return_error(gs_error_rangecheck);

    make_real(op, log10(num));

    return 0;

}

/* - rand <int> */

static int

zrand(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

        /*

         * We use an algorithm from CACM 31 no. 10, pp. 1192-1201,

         * October 1988.  According to a posting by Ed Taft on

         * comp.lang.postscript, Level 2 (Adobe) PostScript interpreters

         * use this algorithm too:

         *      x[n+1] = (16807 * x[n]) mod (2^31 - 1)

         */

#define A 16807

#define M 0x7fffffff

#define Q 127773    /* M / A */

#define R 2836      /* M % A */

    zrand_state = A * (zrand_state % Q) - R * (zrand_state / Q);

    /* Note that zrand_state cannot be 0 here. */

    if (zrand_state <= 0)

        zrand_state += M;

#undef A

#undef M

#undef Q

#undef R

    push(1);

    make_int(op, zrand_state);

    return 0;

}

/* <int> srand - */

static int

zsrand(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    int state;

    check_type(*op, t_integer);

    state = op->value.intval;

    /*

     * The following somewhat bizarre adjustments are according to

     * public information from Adobe describing their implementation.

     */

    if (state < 1)

        state = -(state % 0x7ffffffe) + 1;

    else if (state > 0x7ffffffe)

        state = 0x7ffffffe;

    zrand_state = state;

    pop(1);

    return 0;

}

/* - rrand <int> */

static int

zrrand(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    push(1);

    make_int(op, zrand_state);

    return 0;

}

/* ------ Initialization procedure ------ */

const op_def zmath_op_defs[] =

{

    {"1arccos", zarccos}, /* extension */

    {"1arcsin", zarcsin}, /* extension */

    {"2atan", zatan},

    {"1cos", zcos},

    {"2exp", zexp},

    {"1ln", zln},

    {"1log", zlog},

    {"0rand", zrand},

    {"0rrand", zrrand},

    {"1sin", zsin},

    {"1sqrt", zsqrt},

    {"1srand", zsrand},

    op_def_end(0)

};