.data.asciz "@(#) low.s 1.1 92/07/30 Copyr 1986 Sun Micro".even.text| Copyright (C) 1986 by Sun Microsystems, Inc.! @(#) low.s 1.1 92/07/30 !! This source code is a product of Sun Microsystems, Inc. and is provided! for unrestricted use provided that this legend is included on all tape! media and as a part of the software program in whole or part.  Users! may copy or modify this source code without charge, but are not authorized! to license or distribute it to anyone else except as part of a product or! program developed by the user.!! THIS PROGRAM CONTAINS SOURCE CODE COPYRIGHTED BY SUN MICROSYSTEMS, INC.! AND IS LICENSED TO SUNSOFT, INC., A SUBSIDIARY OF SUN MICROSYSTEMS, INC.! SUN MICROSYSTEMS, INC., MAKES NO REPRESENTATIONS ABOUT THE SUITABLITY! OF SUCH SOURCE CODE FOR ANY PURPOSE.  IT IS PROVIDED "AS IS" WITHOUT! EXPRESS OR IMPLIED WARRANTY OF ANY KIND.  SUN MICROSYSTEMS, INC. DISCLAIMS! ALL WARRANTIES WITH REGARD TO SUCH SOURCE CODE, INCLUDING ALL IMPLIED! 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Mountain View, California 94043#include "low.h".text.globl	___schedule.globl	___real_sig.globl	___do_agent.globl	___asmdebug.globl	___Curproc.globl	___EventsPending.globl	___AsynchLock.globl	___fake_sig.globl	___exchelpclean.globl	___exc_trap.globl	___NuggetSP|| assembly language support routines|| a7 is the stack| __swtch()| switch context when not at interrupt level and the new process| was not switched out asynchronously.| Volatile registers are not restored (d0/d1, a0/a1).| Must be called while LOCKED.|| Context is restored BEFORE UNLOCK (i.e., clearing AsynchLock)| so that any interrupt will capture the correct context| (i.e., save the "backing store" version of the registers,| not the values in the registers at the time ___swtch is called).| We LOCK before calling fake_sig to prevent intrerrupts from| changing anything before fake_sig causes a scheduling decision.| We UNLOCK before testing EventsPending so a interrupt will| cause scheduling (and not just save info and set EventsPending),| even if we decided that EventsPending was false| (and then immediately got an interrupt).| Once we decided that EventsPending is true, it is safe to LOCK| again because setting EventsPending is idempotent.ENTRY(swtch)	movl	___Curproc, a0		| pointer to client context	moveml	a0@(REGOFFSET), #0xfcfc	| restore client regs and new sp	clrl	___AsynchLock		| allow interrupts	tstl	___EventsPending	| check for pending events	jeq	1f			| none	movl	#1, ___AsynchLock	| prevent interrupts from touching regs	movl	___NuggetSP, sp		| don't use client stack for interrupts	jbsr	___fake_sig		| fake an interrupt	| NOTREACHED1:	rts				| back to client| __checkpoint()| Save context and reschedule.| The context will have the return address of the caller of| ___checkpoint on the stack so upon rescheduling it will look| like checkpoint() just returned.| Should be called while LOCKED. When checkpoint() "returns" though,| the state is UNLOCKED.ENTRY(checkpoint)	movl	___Curproc, a0	moveml	#0xfcfc, a0@(REGOFFSET)	| save volatile registers	movl	___NuggetSP, sp		| don't use client stack now	jra	___schedule	| NOTREACHED| __unlock()| Unlock a critical section.| If events occurred while LOCKED, call fake_sig| to simulate an interrupt and cause all pending events to be processed.| Context must be saved before calling fake_sig because the saved context| does not reflect reality and fake_sig will cause a scheduling decision.| Context is saved while LOCKED to prevent interrupts from preserving| an incorrect state before the correct state is established.| EventsPending is tested while UNLOCKED to avoid deadlocks as described in| the swtch() code.ENTRY(unlock)	clrl	___AsynchLock	tstl	___EventsPending	jeq	1f	movl	#1, ___AsynchLock	| prevent interrupts from touching regs	movl	___Curproc, a0	moveml	#0xfcfc, a0@(REGOFFSET)	| save return cntxt; __fake_sig doesn't	movl	___NuggetSP, sp		| don't use client stack now	jbsr	___fake_sig	| NOTREACHED1:	rts| __excreturn()| return value to exception handler upon an excraise.| the return address is on the stack.| note that normal context switching does not restore d0| so we do the exception handle return| as if the user was calling a function returning a value.ENTRY(excreturn)	movl	sp@+, d0		| return pattern	rts| __exccleanup()| a procedure handling exceptions has its return address replaced| by exccleanup.| initially, the procedure return address is at the top of the stack.| it is replaced by exccleanup which is called instead of returning.| We pretend that the stack is as it would be if we were about to| return to the procedure. __exchelpclean makes this true and we return.ENTRY(exccleanup)	subqw	#4, sp			| pretend real return address is there	movl	d0, sp@-		| save return value if any	jsr	___exchelpclean		| this guy restores the original ret addr	movl	sp@+, d0		| restore return value	rts| __sigtrap()| signum is on the stack|ENTRY(sigtrap)	moveml	#0xC0C0, sp@-	/* save C scratch regs */	movl	sp@(16), sp@-	jsr	___exc_trap	addqw	#4, sp	moveml	sp@+,#0x0303	/* restore regs */	addqw	#4, sp	rts| __interrupt()| our own version of sigtramp with no floating point stuff saved| called when an interrupt or trap occurs.ENTRY(interrupt)	moveml	a0/a1/d0/d1,sp@-	/* save C scratch regs */	movl	sp@(0+28),sp@-		/* push addr */	movl	sp@(4+24),sp@-		/* push scp address */	movl	sp@(8+20),sp@-		/* push code */	movl	sp@(12+16),sp@-		/* push signal number */	jsr	___real_sig		/* call realsig */	addl	#16,sp			/* pop args */	tstl	d0			/* need to save full state? */	jeq	1f			/* no */	movl	___Curproc, a0	moveml	a2-a6/d2-d7, a0@(REGOFFSET)	| save general regs except sp	movl	sp@(0), a0@(REGOFFSET+48+0)	| d0	movl	sp@(4), a0@(REGOFFSET+48+4)	| d1	movl	sp@(8), a0@(REGOFFSET+48+8)	| a0	movl	sp@(12), a0@(REGOFFSET+48+12)	| a1	jsr	___do_agent			| map interrupt1:	moveml	sp@+,a0/a1/d0/d1	/* restore regs */	addl	#8,sp			/* pop signo, code, scp now on top */	pea	139			/* call sigcleanup(scp) */	trap	#0	/*NOTREACHED*/| __fp_save()| routines to save and restore floating point context.| Each is called with a pointer to the floating point context as an arg.| This context has FPSAVESIZE bytes of space.#define FP_UNSPECIFIED	0#define FP_SOFTWARE	1#define FP_SKYFFP	2#define FP_MC68881	3#define FP_SUNFPA	4.globl	_getfptype, ffpa_save, f68881_save, fsky_saveENTRY(fp_save)	jsr	_getfptype		| get fp_switch value into d0	movl	sp@(4), a0		| get pointer to fp context	movel	d0, a0@+		| save fp_switch for fp_restore	cmpw	#FP_SUNFPA, d0	jne	3f	jsr	ffpa_save	bras	9f3:	cmpw	#FP_MC68881, d0	bnes	2f	jsr	f68881_save	bras	9f2:	cmpw	#FP_SKYFFP, d0	bnes	9f	jsr	fsky_save9:	rts| __fp_restore().globl	ffpa_restore, f68881_restore, fsky_restoreENTRY(fp_restore)	movl	sp@(4), a0	movel	a0@+, d0	| retrieve saved fp_switch	cmpw	#FP_SUNFPA, d0	jne	3f	jsr	ffpa_restore	bras	9f3:	cmpw	#FP_MC68881, d0	bnes	2f	jsr	f68881_restore	bras	9f2:	cmpw	#FP_SKYFFP, d0	bnes	9f	jsr	fsky_restore9:	rts| stripped-down version of fp stuff from /usr/src/lib/libc/crt/fp_save.s| with ALL regs saved/restored#define	COMREG	-4	/* Sky command register offset from __skybase. */#define	STCREG	-2	/* Sky status register offset from __skybase. */#define SKYSAVE 0x1040	/* Sky context save command. */#define SKYRESTORE 0x1041 /* Sky context restore command. */#define SKYNOP 0x1063 	/* Sky noop command. */#define IOCTL	0x40020000#define	FPABASEADDRESS	0xe0000000f68881_save:	fmovem	fp0-fp7, a0@	fmovem	fpcr/fpsr/fpiar, a0@(96)	rtsf68881_restore:	fmovem	a0@+, fp0-fp7	fmovem	a0@, fpcr/fpsr/fpiar	rts.globl	_getskyfdfsky_save:	movel	__skybase,a11:	movew	a1@(STCREG),d0	btst	#14,d0	beqs	2f			| Branch if busy.	movew	#SKYNOP,a0@(32)	bras	8f2:	tstw	a1@(STCREG)	bpls	1b			| Branch if i/o not ready.	pea	a0@(32)			| Push address of pc save area.	movel	#IOCTL,sp@-	jsr	_getskyfd		| obtain __sky_fd	movl	d0,sp@-			| Push sky descriptor.skyioctl:	jsr	_ioctl	addl	#12,sp			| Remove parameters.8:	movew	#SKYNOP,a1@(COMREG)	movew	#SKYSAVE,a1@(COMREG)	movel	a1@,a0@	movel	a1@,a0@(4)	movel	a1@,a0@(8)	movel	a1@,a0@(12)	movel	a1@,a0@(16)	movel	a1@,a0@(20)	movel	a1@,a0@(24)	movel	a1@,a0@(28)	rtsfsky_restore:	movel	__skybase,a11:	movew	a1@(STCREG),d0	btst	#14,d0	beqs	2f			| Branch if busy.	bras	8f2:	tstw	a1@(STCREG)	bpls	1b			| Branch if i/o not ready.	pea	a0@(36)			| Push address of scratch area.	movel	#IOCTL,sp@-	jsr	_getskyfd	movel	d0,sp@-			| Push sky descriptor.rskyioctl:	jsr	_ioctl	addl	#12,sp			| Remove parameters.8:	movew	#SKYNOP,a1@(COMREG)	movew	#SKYRESTORE,a1@(COMREG)	movel	a0@,a1@	movel	a0@(4),a1@	movel	a0@(8),a1@	movel	a0@(12),a1@	movel	a0@(16),a1@	movel	a0@(20),a1@	movel	a0@(24),a1@	movel	a0@(28),a1@1:	movew	a1@(STCREG),d0	btst	#14,d0	beqs	1b	movew	a0@(32),a1@(COMREG)	rtsffpa_save:	fmovem	fp0-fp7,a0@	addl	#96,a0	fmovem	fpcr/fpsr/fpiar,a0@+	movel	#(FPABASEADDRESS+0xf14),a1	movel	a1@+,a0@+		| Stable read imask.	movel	a1@+,a0@+		| Stable read load_ptr.	movel	a1@+,a0@+		| Stable read ierr.	movel	a1@+,a0@+		| Active instruction.	movel	a1@+,a0@+		| Active data 1.	movel	a1@+,a0@+		| Active data 2.	movel	a1@+,a0@+		| Next instruction.	movel	a1@+,a0@+		| Next data 1.	movel	a1@+,a0@+		| Next data 2.	movel	a1@+,a0@+		| Stable read weitek mode.	movel	a1@+,a0@+		| Stable read weitek status.	movel	#0,0xe0000f84		| Clear pipe.	movel	#(FPABASEADDRESS+0xe00),a1	movel	a1@+,a0@+		| fpa0	movel	a1@+,a0@+		| fpa0	movel	a1@+,a0@+		| fpa1	movel	a1@+,a0@+		| fpa1	movel	a1@+,a0@+		| fpa2	movel	a1@+,a0@+		| fpa2	movel	a1@+,a0@+		| fpa3	movel	a1@+,a0@+		| fpa3|	Set up almost like a new context.	movel	#(FPABASEADDRESS),a1	movel	#0,a1@(0xf1c)		| Clear ierr.	movel	#0,a1@(0xf14)		| Set imask = 0 since SIGFPE					| may already be signalled.	fpmove@1 #2,fpamode		| Set FPA mode to default.	fmovel	#0,fpsr	fmovel	#0,fpcr	rtsffpa_restore:	movel	#0,0xe0000f84		|  Clear pipe.	fmovem	a0@+,fp0-fp7	fmovem	a0@+,fpcr/fpsr/fpiar	addl	#44,a0	movel	#(FPABASEADDRESS+0xc00),a1	movel	a0@+,a1@+		| fpa0	movel	a0@+,a1@+		| fpa0	movel	a0@+,a1@+		| fpa1	movel	a0@+,a1@+		| fpa1	movel	a0@+,a1@+		| fpa2	movel	a0@+,a1@+		| fpa2	movel	a0@+,a1@+		| fpa3	movel	a0@+,a1@+		| fpa3	subl	#76,a0	movel	#(FPABASEADDRESS+0xf14),a1	movel	a0@+,a1@+ 		|  imask.	movel	a0@+,a1@+		|  load_ptr.	movel	a0@+,a1@+		|  ierr.	movel	#(FPABASEADDRESS),a1	movel	a0@(24),d0	andl	#0xf,d0			| Clear all but bottom bits.	fpmove@1	d0,fpamode	fpmove@1	a0@(28),fpastatus	movel	#0,a1@(0x9c4)		| Rewrite shadow registers!	movel	a0@,d0			| Load active instruction.	lea	a0@(8),a0		| Point to active data.	jsr	ffpa_rewrite		| Restore active instruction.	movel	a0@(-4),d0		| Load next instruction.	lea	a0@(8),a0		| Point to next data.	jsr	ffpa_rewrite		| Restore next instruction.	rtsffpa_rewrite:	swap	d0	btst	#15,d0	bnes	9f			| Quit if invalid.	andw	#0x1ffc,d0		| Clear bogus bits.	movel	a0@,a1@(0,d0:w)	swap	d0	btst	#15,d0	bnes	9f			| Quit if invalid.	andw	#0x1ffc,d0		| Clear bogus bits.	movel	a0@(4),a1@(0,d0:w)9:	rts