xref: /csrg-svn/sys/tahoe/align/Awrite_byte.c (revision 45760)
1*45760Sbostic /*-
2*45760Sbostic  * Copyright (c) 1986 The Regents of the University of California.
3*45760Sbostic  * All rights reserved.
4*45760Sbostic  *
5*45760Sbostic  * This code is derived from software contributed to Berkeley by
6*45760Sbostic  * Computer Consoles Inc.
7*45760Sbostic  *
8*45760Sbostic  * %sccs.include.redist.c%
9*45760Sbostic  *
10*45760Sbostic  *	@(#)Awrite_byte.c	7.1 (Berkeley) 12/06/90
11*45760Sbostic  */
1229642Ssam 
1345699Sbostic #include	"align.h"
1429642Ssam 
write_byte(infop,byte,where)1529642Ssam write_byte (infop,byte, where)
1629642Ssam process_info	*infop;
1729642Ssam long		byte;
1829642Ssam struct oprnd 	*where;
1929642Ssam /*
2029642Ssam /*	Put the 'byte' at the given address in
2129642Ssam /*	tahoe's memory.
2229642Ssam /*
2329642Ssam /*	1. Only the least significant byte is written.
2429642Ssam /*
2529642Ssam /**************************************************/
2629642Ssam {
2729642Ssam 	register struct operand_des *look_at;
2829642Ssam 
2929642Ssam 	look_at = &Table[opCODE].operand[last_operand];
3029642Ssam 	if (! (look_at->add_modes & NOVF))
3129642Ssam 		if (byte > 0x7f || byte < -0x80) overflow_1;
3229642Ssam 	if (!(where->mode & W)) exception(infop, ILL_ADDRMOD);
3329642Ssam 	switch (where->mode & ADDFIELD)	/* Mask out R/W bits */
3429642Ssam 	{
3529642Ssam 	case Add:
3629642Ssam 		put_byte(infop, byte, where->address);
3729642Ssam 		break;
3829642Ssam 	case Dir:
3929642Ssam 		Replace (infop, where->reg_number, byte);
4029642Ssam 		break;
4129642Ssam 	case SPmode:
4229642Ssam 		where->mode = where->mode & ~SPmode | Add;
4329642Ssam 		write_longword (infop, byte, where);
4429642Ssam 		break;
4529642Ssam 	default:
4629642Ssam 		printf("Unknown destination in write_byte (alignment code)\n");
4729642Ssam 	};
4829642Ssam }
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