Mercurial > hg > xemacs-beta

view src/alloca.s @ 4844:91b3d00e717f

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Various cleanups for Dynarr code, from Unicode-internal ws dynarr.c: Add comment explaining Dynarr_largest() use. dynarr.c: In Dynarr_insert_many(), don't call Dynarr_resize() unless we actually need to resize, and note that an assert() that we are inserting at or below the current end could be wrong if code wants to access stuff between `len' and `largest'. dynarr.c: Don't just Dynarr_resize() to the right size; instead use Dynarr_reset() then Dynarr_add_many(), so that the 'len' and 'largest' and such get set properly. dynarr.c, faces.c, gutter.c, lisp.h, lread.c, lrecord.h, redisplay-output.c, redisplay.c: Rename Dynarr member 'cur' to 'len' since it's the length of the dynarr, not really a pointer to a "current insertion point". Use type_checking_assert() instead of just assert() in some places. Add additional assertions (Dynarr_verify*()) to check that we're being given positions within range. Use them in Dynarr_at, Dynarr_atp, etc. New Dynarr_atp_allow_end() for retrieving a pointer to a position that might be the element past the last one. New Dynarr_past_lastp() to retrieve a pointer to the position past the last one, using Dynarr_atp_allow_end(). Change code appropriately to use it. Rename Dynarr_end() to Dynarr_lastp() (pointer to the last element) for clarity, and change code appropriately to use it. Change code appropriately to use Dynarr_begin(). Rewrite Dynarr_add_many(). New version can accept a NULL pointer to mean "reserve space but don't put anything in it". Used by stack_like_malloc().
author Ben Wing <ben@xemacs.org>
date Wed, 13 Jan 2010 04:07:42 -0600
parents aa5ed11f473b
children 308d34e9f07d
line wrap: on
line source

/* `alloca' standard 4.2 subroutine for 68000's and 16000's and others.
   Copyright (C) 1985, 1986, 1988 Free Software Foundation, Inc.

This file is part of XEmacs.

XEmacs is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

XEmacs is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with XEmacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Synched up with: FSF 19.30. */

/* Both 68000 systems I have run this on have had broken versions of alloca.
   Also, I am told that non-berkeley systems do not have it at all.
   So replace whatever system-provided alloca there may be
   on all 68000 systems.  */

#define NOT_C_CODE
#ifdef emacs
#include <config.h>
#else
#include "config.h"
#endif

#ifndef HAVE_ALLOCA  /* define this to use system's alloca */

#ifndef m68k
#ifndef m68000
you
lose!!
#endif /* m68000 */
#endif /* m68k */


#ifdef m68k			/* SGS assembler totally different */
	file	"alloca.s"
	global	alloca
alloca:
	mov.l	(%sp)+,%a1	# pop return addr from top of stack
	mov.l	(%sp)+,%d0	# pop size in bytes from top of stack
	add.l	&R%1,%d0	# round size up to long word
	and.l	&-4,%d0		# mask out lower two bits of size
	sub.l	%d0,%sp		# allocate by moving stack pointer
	tst.b	P%1(%sp)	# stack probe to allocate pages
	mov.l	%sp,%a0		# return pointer as pointer
	mov.l	%sp,%d0		# return pointer as int to avoid disaster
	add.l	&-4,%sp		# new top of stack
	jmp	(%a1)		# not a normal return
	set	S%1,64		# safety factor for C compiler scratch
	set	R%1,3+S%1	# add to size for rounding
	set	P%1,-132	# probe this far below current top of stack

#else /* not m68k */

#ifdef m68000

/* Some systems want the _, some do not.  Win with both kinds.  */
.globl	_alloca
_alloca:
.globl	alloca
alloca:
	movl	sp@+,a0
	movl	a7,d0
	subl	sp@,d0
	andl	#~3,d0
	movl	d0,sp
	tstb	sp@(0)		/* Make stack pages exist  */
				/* Needed on certain systems
				   that lack true demand paging */
	addql	#4,d0
	jmp	a0@

#endif /* m68000 */
#endif /* not m68k */

#endif /* not HAVE_ALLOCA */