/* Copyright (C) 1989, 1992, 1993, 1994, 1997, 1998 Aladdin Enterprises.  All rights reserved.

   This file is part of Aladdin Ghostscript.

   Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
   or distributor accepts any responsibility for the consequences of using it,
   or for whether it serves any particular purpose or works at all, unless he
   or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
   License (the "License") for full details.

   Every copy of Aladdin Ghostscript must include a copy of the License,
   normally in a plain ASCII text file named PUBLIC.  The License grants you
   the right to copy, modify and redistribute Aladdin Ghostscript, but only
   under certain conditions described in the License.  Among other things, the
   License requires that the copyright notice and this notice be preserved on
   all copies.
 */

/*$Id: zarith.c $ */
/* Arithmetic operators */
#include "math_.h"
#include "ghost.h"
#include "oper.h"
#include "store.h"

/****** NOTE: none of the arithmetic operators  ******/
/****** currently check for floating exceptions ******/

/* Define max and min values for what will fit in value.intval. */
#define MIN_INTVAL min_long
#define MAX_INTVAL max_long
#define MAX_HALF_INTVAL ((1 << (size_of(long) / 2 - 1)) - 1)

/* <num1> <num2> add <sum> */
/* We make this into a separate procedure because */
/* the interpreter will almost always call it directly. */
int
zop_add(register os_ptr op)
{
    switch (r_type(op)) {
    default:
	return_op_typecheck(op);
    case t_real:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval += op->value.realval;
	    break;
	case t_integer:
	    make_real(op - 1, (double)op[-1].value.intval + op->value.realval);
	}
	break;
    case t_integer:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval += (double)op->value.intval;
	    break;
	case t_integer: {
	    long int2 = op->value.intval;

	    if (((op[-1].value.intval += int2) ^ int2) < 0 &&
		((op[-1].value.intval - int2) ^ int2) >= 0
		) {			/* Overflow, convert to real */
		make_real(op - 1, (double)(op[-1].value.intval - int2) + int2);
	    }
	}
	}
    }
    return 0;
}
int
zadd(os_ptr op)
{
    int code = zop_add(op);

    if (code == 0) {
	pop(1);
    }
    return code;
}

/* <num1> <num2> div <real_quotient> */
private int
zdiv(register os_ptr op)
{
    register os_ptr op1 = op - 1;

    /* We can't use the non_int_cases macro, */
    /* because we have to check explicitly for op == 0. */
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    if (op->value.realval == 0)
		return_error(e_undefinedresult);
	    switch (r_type(op1)) {
		default:
		    return_op_typecheck(op1);
		case t_real:
		    op1->value.realval /= op->value.realval;
		    break;
		case t_integer:
		    make_real(op1, (double)op1->value.intval / op->value.realval);
	    }
	    break;
	case t_integer:
	    if (op->value.intval == 0)
		return_error(e_undefinedresult);
	    switch (r_type(op1)) {
		default:
		    return_op_typecheck(op1);
		case t_real:
		    op1->value.realval /= (double)op->value.intval;
		    break;
		case t_integer:
		    make_real(op1, (double)op1->value.intval / (double)op->value.intval);
	    }
    }
    pop(1);
    return 0;
}

/* <num1> <num2> mul <product> */
private int
zmul(register os_ptr op)
{
    switch (r_type(op)) {
    default:
	return_op_typecheck(op);
    case t_real:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval *= op->value.realval;
	    break;
	case t_integer:
	    make_real(op - 1, (double)op[-1].value.intval * op->value.realval);
	}
	break;
    case t_integer:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval *= (double)op->value.intval;
	    break;
	case t_integer: {
	    long int1 = op[-1].value.intval;
	    long int2 = op->value.intval;
	    long abs1 = (int1 >= 0 ? int1 : -int1);
	    long abs2 = (int2 >= 0 ? int2 : -int2);
	    float fprod;

	    if ((abs1 > MAX_HALF_INTVAL || abs2 > MAX_HALF_INTVAL) &&
		/* At least one of the operands is very large. */
		/* Check for integer overflow. */
		abs1 != 0 &&
		abs2 > MAX_INTVAL / abs1 &&
		/* Check for the boundary case */
		(fprod = (float)int1 * int2,
		 (int1 * int2 != MIN_INTVAL ||
		  fprod != (float)MIN_INTVAL))
		)
		make_real(op - 1, fprod);
	    else
		op[-1].value.intval = int1 * int2;
	}
	}
    }
    pop(1);
    return 0;
}

/* <num1> <num2> sub <difference> */
/* We make this into a separate procedure because */
/* the interpreter will almost always call it directly. */
int
zop_sub(register os_ptr op)
{
    switch (r_type(op)) {
    default:
	return_op_typecheck(op);
    case t_real:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval -= op->value.realval;
	    break;
	case t_integer:
	    make_real(op - 1, (double)op[-1].value.intval - op->value.realval);
	}
	break;
    case t_integer:
	switch (r_type(op - 1)) {
	default:
	    return_op_typecheck(op - 1);
	case t_real:
	    op[-1].value.realval -= (double)op->value.intval;
	    break;
	case t_integer: {
	    long int1 = op[-1].value.intval;

	    if ((int1 ^ (op[-1].value.intval = int1 - op->value.intval)) < 0 &&
		(int1 ^ op->value.intval) < 0
		) {			/* Overflow, convert to real */
		make_real(op - 1, (float)int1 - op->value.intval);
	    }
	}
	}
    }
    return 0;
}
int
zsub(os_ptr op)
{
    int code = zop_sub(op);

    if (code == 0) {
	pop(1);
    }
    return code;
}

/* <num1> <num2> idiv <int_quotient> */
private int
zidiv(register os_ptr op)
{
    check_type(*op, t_integer);
    check_type(op[-1], t_integer);
    if (op->value.intval == 0)
	return_error(e_undefinedresult);
    if ((op[-1].value.intval /= op->value.intval) ==
	MIN_INTVAL && op->value.intval == -1
	) {			/* Anomalous boundary case, fail. */
	return_error(e_rangecheck);
    }
    pop(1);
    return 0;
}

/* <int1> <int2> mod <remainder> */
private int
zmod(register os_ptr op)
{
    check_type(*op, t_integer);
    check_type(op[-1], t_integer);
    if (op->value.intval == 0)
	return_error(e_undefinedresult);
    op[-1].value.intval %= op->value.intval;
    pop(1);
    return 0;
}

/* <num1> neg <num2> */
private int
zneg(register os_ptr op)
{
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    op->value.realval = -op->value.realval;
	    break;
	case t_integer:
	    if (op->value.intval == MIN_INTVAL)
		make_real(op, -(float)MIN_INTVAL);
	    else
		op->value.intval = -op->value.intval;
    }
    return 0;
}

/* <num1> ceiling <num2> */
private int
zceiling(register os_ptr op)
{
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    op->value.realval = ceil(op->value.realval);
	case t_integer:;
    }
    return 0;
}

/* <num1> floor <num2> */
private int
zfloor(register os_ptr op)
{
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    op->value.realval = floor(op->value.realval);
	case t_integer:;
    }
    return 0;
}

/* <num1> round <num2> */
private int
zround(register os_ptr op)
{
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    op->value.realval = floor(op->value.realval + 0.5);
	case t_integer:;
    }
    return 0;
}

/* <num1> truncate <num2> */
private int
ztruncate(register os_ptr op)
{
    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    op->value.realval =
		(op->value.realval < 0.0 ?
		 ceil(op->value.realval) :
		 floor(op->value.realval));
	case t_integer:;
    }
    return 0;
}

/* Non-standard operators */

/* <int1> <int2> .bitadd <sum> */
private int
zbitadd(register os_ptr op)
{
    check_type(*op, t_integer);
    check_type(op[-1], t_integer);
    op[-1].value.intval += op->value.intval;
    pop(1);
    return 0;
}

/* ------ Initialization table ------ */

const op_def zarith_op_defs[] =
{
    {"2add", zadd},
    {"2.bitadd", zbitadd},
    {"1ceiling", zceiling},
    {"2div", zdiv},
    {"2idiv", zidiv},
    {"1floor", zfloor},
    {"2mod", zmod},
    {"2mul", zmul},
    {"1neg", zneg},
    {"1round", zround},
    {"2sub", zsub},
    {"1truncate", ztruncate},
    op_def_end(0)
};
