alloca.s

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1	/* `alloca' standard 4.2 subroutine for 68000's and 16000's and others.
2	Also has _setjmp and _longjmp for pyramids.
3	Copyright (C) 1985, 1986, 1988 Free Software Foundation, Inc.
4
5	This program is free software; you can redistribute it and/or modify it
6	under the terms of the GNU General Public License as published by the
7	Free Software Foundation; either version 2, or (at your option) any
8	later version.
9
10	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.
14
15	You should have received a copy of the GNU General Public License along
16	with this program; if not, write to the Free Software Foundation, Inc.,
17	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
18
19	/* Both 68000 systems I have run this on have had broken versions of alloca.
20	Also, I am told that non-berkeley systems do not have it at all.
21	So replace whatever system-provided alloca there may be
22	on all 68000 systems. */
23
24	#define NOT_C_CODE
25	#ifdef emacs
26	#include <config.h>
27	#else
28	#include "config.h"
29	#endif
30
31	#ifndef HAVE_ALLOCA /* define this to use system's alloca */
32
33	#ifndef hp9000s300
34	#ifndef m68k
35	#ifndef m68000
36	#ifndef WICAT
37	#ifndef ns32000
38	#ifndef ns16000
39	#ifndef sequent
40	#ifndef pyramid
41	#ifndef ATT3B5
42	#ifndef XENIX
43	you
44	lose!!
45	#endif /* XENIX */
46	#endif /* ATT3B5 */
47	#endif /* pyramid */
48	#endif /* sequent */
49	#endif /* ns16000 */
50	#endif /* ns32000 */
51	#endif /* WICAT */
52	#endif /* m68000 */
53	#endif /* m68k */
54	#endif /* hp9000s300 */
55
56
57	#ifdef hp9000s300
58	#ifdef OLD_HP_ASSEMBLER
59	data
60	text
61	globl _alloca
62	_alloca
63	move.l (sp)+,a0 ; pop return addr from top of stack
64	move.l (sp)+,d0 ; pop size in bytes from top of stack
65	add.l #ROUND,d0 ; round size up to long word
66	and.l #MASK,d0 ; mask out lower two bits of size
67	sub.l d0,sp ; allocate by moving stack pointer
68	tst.b PROBE(sp) ; stack probe to allocate pages
69	move.l sp,d0 ; return pointer
70	add.l #-4,sp ; new top of stack
71	jmp (a0) ; not a normal return
72	MASK equ -4 ; Longword alignment
73	ROUND equ 3 ; ditto
74	PROBE equ -128 ; safety buffer for C compiler scratch
75	data
76	#else /* new hp assembler syntax */
77	/*
78	The new compiler does "move.m <registers> (%sp)" to save registers,
79	so we must copy the saved registers when we mung the sp.
80	The old compiler did "move.m <register> <offset>(%a6)", which
81	gave us no trouble
82	*/
83	text
84	set PROBE,-128 # safety for C frame temporaries
85	set MAXREG,22 # d2-d7, a2-a5, fp2-fp7 may have been saved
86	global _alloca
87	_alloca:
88	mov.l (%sp)+,%a0 # return address
89	mov.l (%sp)+,%d0 # number of bytes to allocate
90	mov.l %sp,%a1 # save old sp for register copy
91	mov.l %sp,%d1 # compute new sp
92	sub.l %d0,%d1 # space requested
93	and.l &-4,%d1 # round down to longword
94	sub.l &MAXREG*4,%d1 # space for saving registers
95	mov.l %d1,%sp # save new value of sp
96	tst.b PROBE(%sp) # create pages (sigh)
97	mov.l %a2,%d1 # save reg a2
98	mov.l %sp,%a2
99	move.w &MAXREG-1,%d0
100	copy_regs_loop: /* save caller's saved registers */
101	mov.l (%a1)+,(%a2)+
102	dbra %d0,copy_regs_loop
103	mov.l %a2,%d0 # return value
104	mov.l %d1,%a2 # restore a2
105	add.l &-4,%sp # adjust tos
106	jmp (%a0) # rts
107	#endif /* new hp assembler */
108	#else
109	#ifdef m68k /* SGS assembler totally different */
110	file "alloca.s"
111	global alloca
112	alloca:
113	#ifdef MOTOROLA_DELTA
114	/* slightly modified version of alloca to motorola sysV/68 pcc - based
115	compiler.
116	this compiler saves used registers relative to %sp instead of %fp.
117	alright, just make new copy of saved register set whenever we allocate
118	new space from stack..
119	this is true at last until SVR3V7 . bug has reported to Motorola. */
120	set MAXREG,10 # max no of registers to save (d2-d7, a2-a5)
121	mov.l (%sp)+,%a1 # pop return addr from top of stack
122	mov.l (%sp)+,%d0 # pop size in bytes from top of stack
123	mov.l %sp,%a0 # save stack pointer for register copy
124	addq.l &3,%d0 # round size up to long word
125	andi.l &-4,%d0 # mask out lower two bits of size
126	mov.l %sp,%d1 # compute new value of sp to d1
127	sub.l %d0,%d1 # pseudo-allocate by moving stack pointer
128	sub.l &MAXREG*4,%d1 # allocate more space for saved regs.
129	mov.l %d1,%sp # actual allocation.
130	move.w &MAXREG-1,%d0 # d0 counts saved regs.
131	mov.l %a2,%d1 # preserve a2.
132	mov.l %sp,%a2 # make pointer to new reg save area.
133	copy_regs_loop: # copy stuff from old save area.
134	mov.l (%a0)+,(%a2)+ # save saved register
135	dbra %d0,copy_regs_loop
136	mov.l %a2,%a0 # now a2 is start of allocated space.
137	mov.l %a2,%d0 # return it in both a0 and d0 to play safe.
138	mov.l %d1,%a2 # restore a2.
139	subq.l &4,%sp # new top of stack
140	jmp (%a1) # far below normal return
141	#else /* not MOTOROLA_DELTA */
142	mov.l (%sp)+,%a1 # pop return addr from top of stack
143	mov.l (%sp)+,%d0 # pop size in bytes from top of stack
144	add.l &R%1,%d0 # round size up to long word
145	and.l &-4,%d0 # mask out lower two bits of size
146	sub.l %d0,%sp # allocate by moving stack pointer
147	tst.b P%1(%sp) # stack probe to allocate pages
148	mov.l %sp,%a0 # return pointer as pointer
149	mov.l %sp,%d0 # return pointer as int to avoid disaster
150	add.l &-4,%sp # new top of stack
151	jmp (%a1) # not a normal return
152	set S%1,64 # safety factor for C compiler scratch
153	set R%1,3+S%1 # add to size for rounding
154	set P%1,-132 # probe this far below current top of stack
155	#endif /* not MOTOROLA_DELTA */
156
157	#else /* not m68k */
158
159	#ifdef m68000
160
161	#ifdef WICAT
162	/*
163	* Registers are saved after the corresponding link so we have to explicitly
164	* move them to the top of the stack where they are expected to be.
165	* Since we do not know how many registers were saved in the calling function
166	* we must assume the maximum possible (d2-d7,a2-a5). Hence, we end up
167	* wasting some space on the stack.
168	*
169	* The large probe (tst.b) attempts to make up for the fact that we have
170	* potentially used up the space that the caller probed for its own needs.
171	*/
172	.procss m0
173	.config "68000 1"
174	.module _alloca
175	MAXREG: .const 10
176	.sect text
177	.global _alloca
178	_alloca:
179	move.l (sp)+,a1 ; pop return address
180	move.l (sp)+,d0 ; pop allocation size
181	move.l sp,d1 ; get current SP value
182	sub.l d0,d1 ; adjust to reflect required size...
183	sub.l #MAXREG*4,d1 ; ...and space needed for registers
184	and.l #-4,d1 ; backup to longword boundary
185	move.l sp,a0 ; save old SP value for register copy
186	move.l d1,sp ; set the new SP value
187	tst.b -4096(sp) ; grab an extra page (to cover caller)
188	move.l a2,d1 ; save callers register
189	move.l sp,a2
190	move.w #MAXREG-1,d0 ; # of longwords to copy
191	loop: move.l (a0)+,(a2)+ ; copy registers...
192	dbra d0,loop ; ...til there are no more
193	move.l a2,d0 ; end of register area is addr for new space
194	move.l d1,a2 ; restore saved a2.
195	addq.l #4,sp ; caller will increment sp by 4 after return.
196	move.l d0,a0 ; return value in both a0 and d0.
197	jmp (a1)
198	.end _alloca
199	#else
200
201	/* Some systems want the _, some do not. Win with both kinds. */
202	.globl _alloca
203	_alloca:
204	.globl alloca
205	alloca:
206	movl sp@+,a0
207	movl a7,d0
208	subl sp@,d0
209	andl #~3,d0
210	movl d0,sp
211	tstb sp@(0) /* Make stack pages exist */
212	/* Needed on certain systems
213	that lack true demand paging */
214	addql #4,d0
215	jmp a0@
216
217	#endif /* not WICAT */
218	#endif /* m68000 */
219	#endif /* not m68k */
220	#endif /* not hp9000s300 */
221
222	#if defined (ns16000) \|\| defined (ns32000)
223
224	.text
225	.align 2
226	/* Some systems want the _, some do not. Win with both kinds. */
227	.globl _alloca
228	_alloca:
229	.globl alloca
230	alloca:
231
232	/* Two different assembler syntaxes are used for the same code
233	on different systems. */
234
235	#ifdef sequent
236	#define IM
237	#define REGISTER(x) x
238	#else
239	#ifdef NS5 /* ns SysV assembler */
240	#define IM $
241	#define REGISTER(x) x
242	#else
243	#define IM $
244	#define REGISTER(x) 0(x)
245	#endif
246	#endif
247
248	/*
249	* The ns16000 is a little more difficult, need to copy regs.
250	* Also the code assumes direct linkage call sequence (no mod table crap).
251	* We have to copy registers, and therefore waste 32 bytes.
252	*
253	* Stack layout:
254	* new sp -> junk
255	* registers (copy)
256	* r0 -> new data
257	* \| (orig retval)
258	* \| (orig arg)
259	* old sp -> regs (orig)
260	* local data
261	* fp -> old fp
262	*/
263
264	movd tos,r1 /* pop return addr */
265	negd tos,r0 /* pop amount to allocate */
266	sprd sp,r2
267	addd r2,r0
268	bicb IM/*/3,r0 / 4-byte align */
269	lprd sp,r0
270	adjspb IM/*/36 / space for regs, +4 for caller to pop */
271	movmd 0(r2),4(sp),IM/*/4 / copy regs */
272	movmd 0x10(r2),0x14(sp),IM/**/4
273	jump REGISTER(r1) /* funky return */
274	#endif /* ns16000 or ns32000 */
275
276	#ifdef pyramid
277
278	.globl _alloca
279
280	_alloca: addw $3,pr0 # add 3 (dec) to first argument
281	bicw $3,pr0 # then clear its last 2 bits
282	subw pr0,sp # subtract from SP the val in PR0
283	andw $-32,sp # keep sp aligned on multiple of 32.
284	movw sp,pr0 # ret. current SP
285	ret
286
287	#ifdef PYRAMID_OLD /* This isn't needed in system version 4. */
288	.globl __longjmp
289	.globl _longjmp
290	.globl __setjmp
291	.globl _setjmp
292
293	__longjmp: jump _longjmp
294	__setjmp: jump _setjmp
295	#endif
296
297	#endif /* pyramid */
298
299	#ifdef ATT3B5
300
301	.align 4
302	.globl alloca
303
304	alloca:
305	movw %ap, %r8
306	subw2 $9*4, %r8
307	movw 0(%r8), %r1 /* pc */
308	movw 4(%r8), %fp
309	movw 8(%r8), %sp
310	addw2 %r0, %sp /* make room */
311	movw %sp, %r0 /* return value */
312	jmp (%r1) /* continue... */
313
314	#endif /* ATT3B5 */
315
316	#ifdef XENIX
317
318	.386
319
320	_TEXT segment dword use32 public 'CODE'
321	assume cs:_TEXT
322
323	;-------------------------------------------------------------------------
324
325	public _alloca
326	_alloca proc near
327
328	pop ecx ; return address
329	pop eax ; amount to alloc
330	add eax,3 ; round it to 32-bit boundary
331	and al,11111100B ;
332	mov edx,esp ; current sp in edx
333	sub edx,eax ; lower the stack
334	xchg esp,edx ; start of allocation in esp, old sp in edx
335	mov eax,esp ; return ptr to base in eax
336	push [edx+8] ; save poss. stored reg. values (esi,edi,ebx)
337	push [edx+4] ; on lowered stack
338	push [edx] ;
339	sub esp,4 ; allow for 'add esp, 4'
340	jmp ecx ; jump to return address
341
342	_alloca endp
343
344	_TEXT ends
345
346	end
347
348	#endif /* XENIX */
349
350	#endif /* not HAVE_ALLOCA */

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