2.11BSD/sys/pdp/net_xxx.s

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *	@(#)net_xxx.s	1.3 (2.11BSD GTE) 1/12/95
 */

#include "DEFS.h"
#include "../machine/mch_iopage.h"

/*
 * delay(usec)
 *	long	usec;
 *
 * Delay (approximately) usec micro-seconds.  It really isn't very acurrate
 * since we can be interrupted and take much longer than we intended, but
 * that's alright - we just don't want to come home early ...
 *
 * Copied to the networking from the kernel (mch_xxx.s) so the network could
 * do delays (if_qt.c).
 */
ENTRY(delay)
	mov	2(sp),r0		/ r0 = hiint(usec)
	mov	4(sp),r1		/ r1 = loint(usec)
	ashc	$1,r0			/ sob's ~= 1/2 micro second,
	beq	2f			/ oops, got passed a delay of 0L-leave
	tst	r1
	/*
	 * If the low int of the loop counter is zero, the double sob loop
	 * below will perform correctly, otherwise the high byte must be
	 * increment.
	 */
	beq	1f
	inc	r0			/ correct for looping
1:
	sob	r1,1b			/ sit on our hands for a while ...
	sob	r0,1b
2:
	rts	pc

/*
 * badaddr(addr, len)
 *	caddr_t addr;
 *	int len;
 *
 * See if accessing addr with a len type instruction causes a memory fault.
 * Len is length os access (1=byte, 2=short, 4=long).  Returns 0 if the
 * address is OK, -1 on error.  If either the address or length is odd use
 * a byte test rather than a word test.
 */
ENTRY(badaddr)
	mov	PS,-(sp)		/ save current PS and set previous
	bic	$30000,PS		/   mode = kernel
	mfpd	*$nofault		/ save current nofault and set up
	mov	$4f,-(sp)		/   our own trap
	mtpd	*$nofault
	mov	10(sp),r0		/ if the low bit of either the length
	bis	6(sp),r0		/   or address is
	asr	r0			/   on then use a tstb
	bcc	1f			/ br if word test to be used
	tstb	*6(sp)			/ yes, just do a tstb on the address
	br	2f
1:
	tst	*6(sp)			/ no, try a tst ...
2:
	clr	r0			/ we made it - return success
3:
	mtpd	*$nofault		/ restore previous fault trap
	mov	(sp)+,PS		/   and PS
	rts	pc			/ and return
4:
	mov	$-1,r0			/ we faulted out - return failure
	br	3b


/*
 * locc(mask, size, str)
 * 	u_char mask;
 * 	u_int size;
 * 	u_char *str;
 *
 * Scan through str up to (but not including str[size]) stopping when a
 * character equals mask.  Return number of characters left in str.
 */
ENTRY(locc)
	mov	4(sp),r0		/ r0 = size
	beq	3f			/   exit early if zero
	mov	6(sp),r1		/ r1 = str
	mov	r2,-(sp)		/ r2 = mask
	mov	2+2(sp),r2
1:					/ do
	cmpb	(r1)+,r2		/   if (*str++ == mask)
	beq	2f
	sob	r0,1b			/ while (--size != 0)
2:
	mov	(sp)+,r2		/ restore registers
3:
	rts	pc			/ and return size