usr/src/lib/libpc/PACK.c

/* Copyright (c) 1979 Regents of the University of California */

static char sccsid[] = "@(#)PACK.c 1.3 6/10/81";


/*
 * pack(a,i,z)
 *
 * with:        a: array[m..n] of t
 *      z: packed array[u..v] of t
 *
 * semantics:   for j := u to v do
 *                      z[j] := a[j-u+i];
 *
 * need to check:
 *      1. i >= m
 *      2. i+(v-u) <= n         (i.e. i-m <= (n-m)-(v-u))
 *
 * on stack:    lv(z), lv(a), rv(i) (len 4)
 *
 * move w(t)*(v-u+1) bytes from lv(a)+w(t)*(i-m) to lv(z)
 */

PACK(i, a, z, size_a, lb_a, ub_a, size_z)

        long    i;      /* subscript into a to begin packing */
        char    *a;     /* pointer to structure a */
        char    *z;     /* pointer to structure z */
        long    size_a; /* sizeof(a_type) */
        long    lb_a;   /* lower bound of structure a */
        long    ub_a;   /* (upper bound of a) - (lb_a + sizeof(z_type)) */
        long    size_z; /* sizeof(z_type) */
{
        int             subscr;
        register char   *cp;
        register char   *zp = z;
        register char   *limit;

        subscr = i - lb_a;
        if (subscr < 0 || subscr > ub_a) {
                ERROR("i = %D: Bad i to pack(a,i,z)\n", i);
                return;
        }
        cp = &a[subscr * size_a];
        limit = cp + size_z;
        do      {
                *zp++ = *cp++;
        } while (cp < limit);
}