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/* Copyright (C) 1989, 2000 Aladdin Enterprises.  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.

  For more information about licensing, please refer to

  http://www.ghostscript.com/licensing/. For information on

  commercial licensing, go to http://www.artifex.com/licensing/ or

  contact Artifex Software, Inc., 101 Lucas Valley Road #110,

  San Rafael, CA  94903, U.S.A., +1(415)492-9861.

*/

/* $Id: zmath.c,v 1.5 2002/02/21 22:24:54 giles Exp $ */

/* 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(e_rangecheck);

    make_real(op, sqrt(num));

    return 0;

}

/* <num> arccos <real> */

private 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> */

private 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] == 0.0)

	return_error(e_undefinedresult);

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

	return_error(e_undefinedresult);

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

    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(e_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(e_rangecheck);

    make_real(op, log10(num));

    return 0;

}

/* - rand <int> */

private 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 - */

private int

zsrand(i_ctx_t *i_ctx_p)

{

    os_ptr op = osp;

    long state;

    check_type(*op, t_integer);

    state = op->value.intval;

#if arch_sizeof_long > 4

    /* Trim the state back to 32 bits. */

    state = (int)state;

#endif

    /*

     * 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> */

private 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)

};