/* Copyright (C) 1989, 2000 Aladdin Enterprises.  All rights reserved.
  
  This file is part of AFPL Ghostscript.
  
  AFPL 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 Free Public License (the
  "License") for full details.
  
  Every copy of AFPL 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 AFPL 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,v 1.4 2000/09/19 19:00:52 lpd Exp $ */
/* 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 ******/

/*
 * Many of the procedures in this file are public only so they can be
 * called from the FunctionType 4 interpreter (zfunc4.c).
 */

/* 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 ((1L << (size_of(long) * 4 - 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(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    int code = zop_add(op);

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

/* <num1> <num2> div <real_quotient> */
int
zdiv(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    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> */
int
zmul(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    int code = zop_sub(op);

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

/* <num1> <num2> idiv <int_quotient> */
int
zidiv(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> */
int
zmod(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> */
int
zneg(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> abs <num2> */
int
zabs(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    switch (r_type(op)) {
	default:
	    return_op_typecheck(op);
	case t_real:
	    if (op->value.realval >= 0)
		return 0;
	    break;
	case t_integer:
	    if (op->value.intval >= 0)
		return 0;
	    break;
    }
    return zneg(i_ctx_p);
}

/* <num1> ceiling <num2> */
int
zceiling(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> */
int
zfloor(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> */
int
zround(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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> */
int
ztruncate(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    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[] =
{
    {"1abs", zabs},
    {"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)
};
