M_apm_pad
extern void M_apm_pad(M_APM, int);
M_apm_pad(M_work2, adigits);
M_apm_pad(M_work1, bdigits);
M_apm_pad(M_ain, k); /* fill out the data so the number of */
M_apm_pad(M_bin, k); /* bytes is an exact power of 2 */
M_apm_pad(atmp, (datalength + 3));