[unix-history] / usr / src / sys / tahoe / align / Awrite_byte.c

/*      Awrite_byte.c   1.1     86/07/20        */

#include        "../tahoealign/align.h"

write_byte (infop,byte, where)
process_info    *infop;
long            byte; 
struct oprnd    *where;
/*
/*      Put the 'byte' at the given address in
/*      tahoe's memory.
/*      
/*      1. Only the least significant byte is written.
/*
/**************************************************/
{
       register struct operand_des *look_at;

       look_at = &Table[opCODE].operand[last_operand];
       if (! (look_at->add_modes & NOVF))
               if (byte > 0x7f || byte < -0x80) overflow_1;    
       if (!(where->mode & W)) exception(infop, ILL_ADDRMOD);
       switch (where->mode & ADDFIELD) /* Mask out R/W bits */
       {
       case Add:
               put_byte(infop, byte, where->address);
               break;
       case Dir:
               Replace (infop, where->reg_number, byte);
               break;
       case SPmode:
               where->mode = where->mode & ~SPmode | Add;
               write_longword (infop, byte, where);
               break;
       default:
               printf("Unknown destination in write_byte (alignment code)\n");
       };
}