/*
* Copyright (c) 1987 University of Maryland Department of Computer Science.
* All rights reserved. Permission to copy for any purpose is hereby granted
* so long as this copyright notice remains intact.
*/
/*
* Arithmetic with scaled dimensions
*
* From `TEX.WEB' by D. E. Knuth:
*
* `The principal computations performed by TeX are done entirely in terms
* of integers less than 2^31 in magnitude; and divisions are done only when
* both divident and divisor are nonnegative. Thus, the arithemtic specified
* in this program can be carried out in exactly the same way on a wide
* variety of computers, including some small ones. Why? Because the
* arithmetic calculations need to be spelled out precisely in order to
* guarantee that TeX will produce identical output on different machines.
* If some quantities were rounded differently in different implementations,
* we would find that line breaks and even page breaks might occur in
* different places. Hence the arithmetic of TeX has been designed with
* care, and systems that claim be be implementations of TeX82 should follow
* precisely the calculations as they appear in the present program.'
*
* Thus, this follows the given implementation with few (no) optimizations.
*/
/*
* We do fixed-point arithmetic on `scaled integers'. These should
* be (at least) 32 bits. Note also that it is assumed that certain
* `int' values may be stored in these (usually small, or else one
* of the magic 1<