/* * acm : an aerial combat simulator for X * Copyright (C) 1991,1992 Riley Rainey * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 dated June, 1991. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave., Cambridge, MA 02139, USA. */ /* * Some data structures to perform fast 2-D interpolation * * Alot of aircraft information is in tabular form. We perform linear * interpolation to determine values. In order to speed up that process, * we'll create preprocessed tables. Each entry in the table contains the * upper bound of the domain value (x) and the equation of the line that * defines the data for that interval (y = m * x + b). * * The program ibuild preprocesses the tabular information into a * corresponding C structure that the interpolate() function can use. */ #include <math.h> typedef float float_t; typedef struct { float_t x; /* upper x value for this interval */ float_t m; /* slope of line in this interval */ float_t b; /* y-intercept of line in this interval */ } IEntry; typedef struct { int count; /* entry count in the interpolation table */ float_t minX; /* minimum x value that can be interpolated */ IEntry *entry; /* vector of intterpolation entries */ } ITable; /* * I'm doing this to catch bad interpolation requests. If an invalid * domain value is submitted, (and we're on an IEEE FP system) we'll * get back the IEEE NaN value as the interpolated result. */ #define I_NaN (sqrt(-1.0)) extern float_t interpolate();

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