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/*
* mvme162lx-asm.S -- assembler routines for the MVME stub.
*
* This code was pulled out of mvme162lx-stub.c by Ian Taylor so that I
* could handle different register and label prefixes in a sensible
* way.
*/
/****************************************************************************
THIS SOFTWARE IS NOT COPYRIGHTED
HP offers the following for use in the public domain. HP makes no
warranty with regard to the software or it's performance and the
user accepts the software "AS IS" with all faults.
HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD
TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
****************************************************************************/
#include "asm.h"
.title "mvme162lx-asm.S for m68k"
.globl SYM (registers)
.globl SYM (lastFrame)
.globl SYM (superStack)
.globl SYM (exceptionHook)
.globl SYM (_returnFromException)
.globl SYM (stackPtr)
.globl SYM (handle_exception)
.globl SYM (exceptionSize)
.text
.globl SYM (return_to_super)
SYM (return_to_super):
movel SYM (registers)+60,sp /* get new stack pointer */
movel SYM (lastFrame),a0 /* get last frame info */
bra return_to_any
.globl SYM (return_to_user)
SYM (return_to_user):
movel SYM (registers)+60,a0 /* get usp */
movel a0,usp /* set usp */
movel SYM (superStack),sp /* get original stack pointer */
return_to_any:
movel SYM (lastFrame),a0 /* get last frame info */
movel a0@+,SYM (lastFrame) /* link in previous frame */
addql IMM (8),a0 /* skip over pc, vector#*/
movew a0@+,d0 /* get # of words in cpu frame */
addw d0,a0 /* point to end of data */
addw d0,a0 /* point to end of data */
movel a0,a1
/* copy the stack frame */
subql IMM (1),d0
copyUserLoop:
movew a1@-,sp@-
dbf d0,copyUserLoop
#ifdef __HAVE_68881__
fmoveml SYM (registers)+168,fpcr/fpsr/fpi
fmovemx SYM (registers)+72,fp0-fp7
cmpl IMM (-1),a0@ /* skip frestore flag set ? */
beq skip_frestore
frestore a0@+
skip_frestore:
#endif
moveml SYM (registers),d0-d7/a0-a6
rte /* pop and go! */
/* this function is called immediately when a level 7 interrupt occurs */
/* if the previous interrupt level was 7 then we're already servicing */
/* this interrupt and an rte is in order to return to the debugger. */
/* For the 68000, the offset for sr is 6 due to the jsr return address */
.text
.globl SYM (_debug_level7)
SYM (_debug_level7):
movew d0,sp@-
#ifdef mc68020
movew sp@(2),d0
#else
movew sp@(6),d0
#endif
andiw IMM (0x700),d0
cmpiw IMM (0x700),d0
beq _already7
movew sp@+,d0
bra SYM (_catchException)
_already7:
movew sp@+,d0
#ifndef mc68020
lea sp@(4),sp /* pull off 68000 return address */
#endif
rte
#ifdef mc68020
/* This function is called when a 68020 exception occurs. It saves
* all the cpu and fpcp regs in the _registers array, creates a frame on a
* linked list of frames which has the cpu and fpcp stack frames needed
* to properly restore the context of these processors, and invokes
* an exception handler (remcom_handler).
*
* stack on entry: stack on exit:
* N bytes of junk exception # MSWord
* Exception Format Word exception # MSWord
* Program counter LSWord
* Program counter MSWord
* Status Register
*
*
*/
.text
.globl SYM (_catchException)
SYM (_catchException):
oriw IMM (0x0700),sr /* Disable interrupts */
moveml d0-d7/a0-a6,SYM (registers) /* save registers */
movel SYM (lastFrame),a0 /* last frame pointer */
#ifdef __HAVE_68881__
/* do an fsave, then remember the address to begin a restore from */
fsave a0@-
fmovemx fp0-fp7, SYM (registers)+72
fmoveml fpcr/fpsr/fpi, SYM (registers)+168
#endif
lea SYM (registers),a5 /* get address of registers */
movew sp@,d1 /* get status register */
movew d1,a5@(66) /* save sr */
movel sp@(2),a4 /* save pc in a4 for later use */
movel a4,a5@(68) /* save pc in _regisers[] */
/* figure out how many bytes in the stack frame */
movew sp@(6),d0 /* get '020 exception format */
movew d0,d2 /* make a copy of format word */
andiw IMM (0xf000),d0 /* mask off format type */
rolw IMM (5),d0 /* rotate into the low byte *2 */
lea SYM (exceptionSize),a1
addw d0,a1 /* index into the table */
movew a1@,d0 /* get number of words in frame */
movew d0,d3 /* save it */
subw d0,a0 /* adjust save pointer */
subw d0,a0 /* adjust save pointer(bytes) */
movel a0,a1 /* copy save pointer */
subql IMM (1),d0 /* predecrement loop counter */
/* copy the frame */
saveFrameLoop:
movew sp@+,a1@+
dbf d0,saveFrameLoop
/* now that the stack has been clenaed,
* save the a7 in use at time of exception
*/
movel sp,SYM (superStack) /* save supervisor sp */
andiw IMM (0x2000),d1 /* were we in supervisor mode ? */
beq userMode
movel a7,a5@(60) /* save a7 */
bra a7saveDone
userMode:
movel usp,a1
movel a1,a5@(60) /* save user stack pointer */
a7saveDone:
/* save size of frame */
movew d3,a0@-
/* compute exception number */
andl IMM (0xfff),d2 /* mask off vector offset */
lsrw IMM (2),d2 /* divide by 4 to get vect num */
movel d2,a0@- /* save it */
/* save pc causing exception */
movel a4,a0@-
/* save old frame link and set the new value*/
movel SYM (lastFrame),a1 /* last frame pointer */
movel a1,a0@- /* save pointer to prev frame */
movel a0,SYM (lastFrame)
movel d2,sp@- /* push exception num */
#ifdef TMP_HACK
movel SYM (exceptionHook),a0 /* get address of handler */
jbsr a0@ /* and call it */
#else
jbsr SYM (remcomHandler)
#endif
clrl sp@ /* replace exception num parm with frame ptr */
jbsr SYM (_returnFromException) /* jbsr, but never returns */
#else /* mc68000 */
/* This function is called when an exception occurs. It translates the
* return address found on the stack into an exception vector # which
* is then handled by either handle_exception or a system handler.
* _catchException provides a front end for both.
*
* stack on entry: stack on exit:
* Program counter MSWord exception # MSWord
* Program counter LSWord exception # MSWord
* Status Register
* Return Address MSWord
* Return Address LSWord
*/
.text
.globl SYM (_catchException)
SYM (_catchException):
oriw IMM (0x0700),sr /* Disable interrupts */
moveml d0-d7/a0-a6,SYM (registers) /* save registers */
movel SYM (lastFrame),a0 /* last frame pointer */
#ifdef __HAVE_68881__
/* do an fsave, then remember the address to begin a restore from */
fsave a0@-
fmovemx fp0-fp7, SYM (registers)+72
fmoveml fpcr/fpsr/fpi, SYM (registers)+168
#endif
lea SYM (registers),a5 /* get address of registers */
movel sp@+,d2 /* pop return address */
addl IMM (1530),d2 /* convert return addr to */
divs IMM (6),d2 /* exception number */
extl d2
moveql IMM (3),d3 /* assume a three word frame */
cmpiw IMM (3),d2 /* bus error or address error ? */
bgt normal /* if >3 then normal error */
movel sp@+,a0@- /* copy error info to frame buff*/
movel sp@+,a0@- /* these are never used */
moveql IMM (7),d3 /* this is a 7 word frame */
normal:
movew sp@+,d1 /* pop status register */
movel sp@+,a4 /* pop program counter */
movew d1,a5@(66) /* save sr */
movel a4,a5@(68) /* save pc in _regisers[] */
movel a4,a0@- /* copy pc to frame buffer */
movew d1,a0@- /* copy sr to frame buffer */
movel sp,SYM (superStack) /* save supervisor sp */
andiw IMM (0x2000),d1 /* were we in supervisor mode ? */
beq userMode
movel a7,a5@(60) /* save a7 */
bra saveDone
userMode:
movel usp,a1 /* save user stack pointer */
movel a1,a5@(60) /* save user stack pointer */
saveDone:
movew d3,a0@- /* push frame size in words */
movel d2,a0@- /* push vector number */
movel a4,a0@- /* push exception pc */
/* save old frame link and set the new value */
movel SYM (lastFrame),a1 /* last frame pointer */
movel a1,a0@- /* save pointer to prev frame */
movel a0,SYM (lastFrame)
movel d2,sp@- /* push exception num */
movel SYM (exceptionHook),a0 /* get address of handler */
jbsr a0@ /* and call it */
clrl sp@ /* replace exception num parm with frame ptr */
jbsr SYM (_returnFromException) /* jbsr, but never returns */
#endif /* m68000 */
/*
* remcomHandler is a front end for handle_exception. It moves the
* stack pointer into an area reserved for debugger use in case the
* breakpoint happened in supervisor mode.
*/
.globl SYM (remcomHandler)
SYM (remcomHandler):
addl IMM (4),sp /* pop off return address */
movel sp@+,d0 /* get the exception number */
movel SYM (stackPtr),sp /* move to remcom stack area */
movel d0,sp@- /* push exception onto stack */
jbsr SYM (handle_exception) /* this never returns */
rts /* return */
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