mirror of
https://github.com/autc04/Retro68.git
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735 lines
23 KiB
C
735 lines
23 KiB
C
unsigned long sp_ptr;
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unsigned long pc_ptr;
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int cnt;
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#define UNWIND asm ("movel %/sp, %0" : "=g" (sp_ptr));\
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printf ("\n\t\t== Starting at 0x%x ==\n", sp_ptr);\
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for (cnt=4; cnt <=32; cnt+=4) {\
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printf ("+%d(0x%x): 0x%x\t\t-%d(0x%x): 0x%x\n",\
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cnt, (sp_ptr + cnt), *(unsigned long *)(sp_ptr + cnt),\
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cnt, (sp_ptr - cnt), *(unsigned long *)(sp_ptr - cnt)\
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); }; fflush (stdout);
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/****************************************************************************
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THIS SOFTWARE IS NOT COPYRIGHTED
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HP offers the following for use in the public domain. HP makes no
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warranty with regard to the software or it's performance and the
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user accepts the software "AS IS" with all faults.
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HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD
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TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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****************************************************************************/
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/****************************************************************************
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* Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $
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*
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* Module name: remcom.c $
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* Revision: 1.34 $
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* Date: 91/03/09 12:29:49 $
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* Contributor: Lake Stevens Instrument Division$
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*
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* Description: low level support for gdb debugger. $
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*
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* Considerations: only works on target hardware $
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*
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* Written by: Glenn Engel $
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* ModuleState: Experimental $
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*
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* NOTES: See Below $
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*
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* To enable debugger support, two things need to happen. One, a
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* call to set_debug_traps() is necessary in order to allow any breakpoints
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* or error conditions to be properly intercepted and reported to gdb.
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* Two, a breakpoint needs to be generated to begin communication. This
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* is most easily accomplished by a call to breakpoint(). Breakpoint()
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* simulates a breakpoint by executing a trap #1.
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*
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* Some explanation is probably necessary to explain how exceptions are
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* handled. When an exception is encountered the 68000 pushes the current
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* program counter and status register onto the supervisor stack and then
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* transfers execution to a location specified in it's vector table.
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* The handlers for the exception vectors are hardwired to jmp to an address
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* given by the relation: (exception - 256) * 6. These are decending
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* addresses starting from -6, -12, -18, ... By allowing 6 bytes for
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* each entry, a jsr, jmp, bsr, ... can be used to enter the exception
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* handler. Using a jsr to handle an exception has an added benefit of
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* allowing a single handler to service several exceptions and use the
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* return address as the key differentiation. The vector number can be
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* computed from the return address by [ exception = (addr + 1530) / 6 ].
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* The sole purpose of the routine _catchException is to compute the
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* exception number and push it on the stack in place of the return address.
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* The external function exceptionHandler() is
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* used to attach a specific handler to a specific 68k exception.
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* For 68020 machines, the ability to have a return address around just
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* so the vector can be determined is not necessary because the '020 pushes an
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* extra word onto the stack containing the vector offset
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*
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* Because gdb will sometimes write to the stack area to execute function
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* calls, this program cannot rely on using the supervisor stack so it
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* uses it's own stack area reserved in the int array remcomStack.
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*
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*************
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*
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* The following gdb commands are supported:
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*
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* command function Return value
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*
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* g return the value of the CPU registers hex data or ENN
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* G set the value of the CPU registers OK or ENN
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*
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* mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN
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* MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN
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*
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* c Resume at current address SNN ( signal NN)
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* cAA..AA Continue at address AA..AA SNN
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*
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* s Step one instruction SNN
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* sAA..AA Step one instruction from AA..AA SNN
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*
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* k kill
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*
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* ? What was the last sigval ? SNN (signal NN)
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*
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* All commands and responses are sent with a packet which includes a
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* checksum. A packet consists of
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*
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* $<packet info>#<checksum>.
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*
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* where
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* <packet info> :: <characters representing the command or response>
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* <checksum> :: < two hex digits computed as modulo 256 sum of <packetinfo>>
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*
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* When a packet is received, it is first acknowledged with either '+' or '-'.
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* '+' indicates a successful transfer. '-' indicates a failed transfer.
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*
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* Example:
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*
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* Host: Reply:
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* $m0,10#2a +$00010203040506070809101112131415#42
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*
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****************************************************************************/
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#include <stdio.h>
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#include <string.h>
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#include <setjmp.h>
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#include <_ansi.h>
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/************************************************************************
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*
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* external low-level support routines
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*/
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typedef void (*ExceptionHook)(int); /* pointer to function with int parm */
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typedef void (*Function)(); /* pointer to a function */
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extern int putDebugChar(); /* write a single character */
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extern char getDebugChar(); /* read and return a single char */
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ExceptionHook exceptionHook; /* hook variable for errors/exceptions */
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/************************/
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/* FORWARD DECLARATIONS */
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/************************/
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/** static void initializeRemcomErrorFrame PARAMS ((void)); **/
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static void _DEFUN_VOID (initializeRemcomErrorFrame);
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/************************************************************************/
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/* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/
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/* at least NUMREGBYTES*2 are needed for register packets */
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#define BUFMAX 400
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static char initialized; /* boolean flag. != 0 means we've been initialized */
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int remote_debug = 0; /*** Robs Thu Sep 24 22:18:51 PDT 1992 ***/
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/* debug > 0 prints ill-formed commands in valid packets & checksum errors */
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static const char hexchars[]="0123456789abcdef";
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/* there are 180 bytes of registers on a 68020 w/68881 */
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/* many of the fpa registers are 12 byte (96 bit) registers */
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#define NUMREGBYTES 180
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enum regnames {D0,D1,D2,D3,D4,D5,D6,D7,
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A0,A1,A2,A3,A4,A5,A6,A7,
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PS,PC,
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FP0,FP1,FP2,FP3,FP4,FP5,FP6,FP7,
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FPCONTROL,FPSTATUS,FPIADDR
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};
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typedef struct FrameStruct
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{
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struct FrameStruct *previous;
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int exceptionPC; /* pc value when this frame created */
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int exceptionVector; /* cpu vector causing exception */
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short frameSize; /* size of cpu frame in words */
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short sr; /* for 68000, this not always sr */
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int pc;
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short format;
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int fsaveHeader;
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int morejunk[0]; /* exception frame, fp save... */
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} Frame;
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#define FRAMESIZE 500
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int gdbFrameStack[FRAMESIZE];
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Frame *lastFrame;
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/*
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* these should not be static cuz they can be used outside this module
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*/
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int registers[NUMREGBYTES/4];
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int superStack;
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#define STACKSIZE 10000
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int remcomStack[STACKSIZE/sizeof(int)];
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int* stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1];
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/*
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* In many cases, the system will want to continue exception processing
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* when a continue command is given.
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* oldExceptionHook is a function to invoke in this case.
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*/
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static ExceptionHook oldExceptionHook;
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/* the size of the exception stack on the 68020 varies with the type of
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* exception. The following table is the number of WORDS used
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* for each exception format.
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*/
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const short exceptionSize[] = { 4,4,6,4,4,4,4,4,29,10,16,46,12,4,4,4 };
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/************* jump buffer used for setjmp/longjmp **************************/
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jmp_buf remcomEnv;
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#define BREAKPOINT() asm(" trap #1");
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extern void _DEFUN_VOID (return_to_super);
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extern void _DEFUN_VOID (return_to_user);
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extern void _DEFUN_VOID (_catchException);
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void _returnFromException( Frame *frame )
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{
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/* if no passed in frame, use the last one */
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if (! frame)
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{
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frame = lastFrame;
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frame->frameSize = 4;
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frame->format = 0;
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frame->fsaveHeader = -1; /* restore regs, but we dont have fsave info*/
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}
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#ifndef mc68020
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/* a 68000 cannot use the internal info pushed onto a bus error
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* or address error frame when doing an RTE so don't put this info
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* onto the stack or the stack will creep every time this happens.
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*/
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frame->frameSize=3;
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#endif
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/* throw away any frames in the list after this frame */
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lastFrame = frame;
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frame->sr = registers[(int) PS];
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frame->pc = registers[(int) PC];
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if (registers[(int) PS] & 0x2000)
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{
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/* return to supervisor mode... */
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return_to_super();
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}
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else
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{ /* return to user mode */
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return_to_user();
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}
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}
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int hex(ch)
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char ch;
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{
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if ((ch >= 'a') && (ch <= 'f')) return (ch-'a'+10);
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if ((ch >= '0') && (ch <= '9')) return (ch-'0');
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if ((ch >= 'A') && (ch <= 'F')) return (ch-'A'+10);
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return (-1);
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}
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/* scan for the sequence $<data>#<checksum> */
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void getpacket(buffer)
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char * buffer;
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{
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unsigned char checksum;
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unsigned char xmitcsum;
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int i;
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int count;
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char ch;
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if (remote_debug) {
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printf("\nGETPACKET: sr=0x%x, pc=0x%x, sp=0x%x\n",
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registers[ PS ],
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registers[ PC ],
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registers[ A7 ]
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); fflush (stdout);
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UNWIND
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}
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do {
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/* wait around for the start character, ignore all other characters */
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while ((ch = getDebugChar()) != '$');
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checksum = 0;
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xmitcsum = -1;
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count = 0;
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/* now, read until a # or end of buffer is found */
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while (count < BUFMAX) {
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ch = getDebugChar();
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if (ch == '#') break;
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checksum = checksum + ch;
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buffer[count] = ch;
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count = count + 1;
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}
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buffer[count] = 0;
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if (ch == '#') {
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xmitcsum = hex(getDebugChar()) << 4;
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xmitcsum += hex(getDebugChar());
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if ((remote_debug ) && (checksum != xmitcsum)) {
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fprintf(stderr,"bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n",
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checksum,xmitcsum,buffer);
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}
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if (checksum != xmitcsum) putDebugChar('-'); /* failed checksum */
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else {
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putDebugChar('+'); /* successful transfer */
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/* if a sequence char is present, reply the sequence ID */
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if (buffer[2] == ':') {
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putDebugChar( buffer[0] );
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putDebugChar( buffer[1] );
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/* remove sequence chars from buffer */
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count = strlen(buffer);
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for (i=3; i <= count; i++) buffer[i-3] = buffer[i];
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}
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}
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}
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} while (checksum != xmitcsum);
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}
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/* send the packet in buffer. The host get's one chance to read it.
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This routine does not wait for a positive acknowledge. */
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void putpacket(buffer)
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char * buffer;
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{
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unsigned char checksum;
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int count;
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char ch;
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/* $<packet info>#<checksum>. */
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/*** do {***/
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putDebugChar('$');
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checksum = 0;
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count = 0;
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while (ch=buffer[count]) {
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if (! putDebugChar(ch)) return;
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checksum += ch;
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count += 1;
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}
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putDebugChar('#');
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putDebugChar(hexchars[checksum >> 4]);
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putDebugChar(hexchars[checksum % 16]);
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if (remote_debug) {
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printf("\nPUTPACKET: sr=0x%x, pc=0x%x, sp=0x%x\n",
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registers[ PS ],
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registers[ PC ],
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registers[ A7 ]
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); fflush (stdout);
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UNWIND
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}
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/*** } while (getDebugChar() != '+'); ***/
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/** } while (1 == 0); (getDebugChar() != '+'); **/
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}
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char remcomInBuffer[BUFMAX];
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char remcomOutBuffer[BUFMAX];
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static short error;
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void debug_error(format, parm)
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char * format;
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char * parm;
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{
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if (remote_debug) fprintf(stderr,format,parm);
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}
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/* convert the memory pointed to by mem into hex, placing result in buf */
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/* return a pointer to the last char put in buf (null) */
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char* mem2hex(mem, buf, count)
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char* mem;
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char* buf;
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int count;
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{
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int i;
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unsigned char ch;
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for (i=0;i<count;i++) {
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ch = *mem++;
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*buf++ = hexchars[ch >> 4];
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*buf++ = hexchars[ch % 16];
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}
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*buf = 0;
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return(buf);
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}
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/* convert the hex array pointed to by buf into binary to be placed in mem */
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/* return a pointer to the character AFTER the last byte written */
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char* hex2mem(buf, mem, count)
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char* buf;
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char* mem;
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int count;
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{
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int i;
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unsigned char ch;
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for (i=0;i<count;i++) {
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ch = hex(*buf++) << 4;
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ch = ch + hex(*buf++);
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*mem++ = ch;
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}
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return(mem);
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}
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/* a bus error has occurred, perform a longjmp
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to return execution and allow handling of the error */
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void handle_buserror()
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{
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longjmp(remcomEnv,1);
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}
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/* this function takes the 68000 exception number and attempts to
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translate this number into a unix compatible signal value */
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int computeSignal( exceptionVector )
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int exceptionVector;
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{
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int sigval;
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switch (exceptionVector) {
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case 2 : sigval = 10; break; /* bus error */
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case 3 : sigval = 10; break; /* address error */
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case 4 : sigval = 4; break; /* illegal instruction */
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case 5 : sigval = 8; break; /* zero divide */
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case 6 : sigval = 16; break; /* chk instruction */
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case 7 : sigval = 16; break; /* trapv instruction */
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case 8 : sigval = 11; break; /* privilege violation */
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case 9 : sigval = 5; break; /* trace trap */
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case 10: sigval = 4; break; /* line 1010 emulator */
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case 11: sigval = 4; break; /* line 1111 emulator */
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case 13: sigval = 8; break; /* floating point err */
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case 31: sigval = 2; break; /* interrupt */
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case 33: sigval = 5; break; /* breakpoint */
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case 40: sigval = 8; break; /* floating point err */
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case 48: sigval = 8; break; /* floating point err */
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case 49: sigval = 8; break; /* floating point err */
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case 50: sigval = 8; break; /* zero divide */
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case 51: sigval = 8; break; /* underflow */
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case 52: sigval = 8; break; /* operand error */
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case 53: sigval = 8; break; /* overflow */
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case 54: sigval = 8; break; /* NAN */
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default:
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sigval = 7; /* "software generated"*/
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}
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return (sigval);
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}
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/**********************************************/
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/* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */
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/* RETURN NUMBER OF CHARS PROCESSED */
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/**********************************************/
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int hexToInt(char **ptr, int *intValue)
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{
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int numChars = 0;
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int hexValue;
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*intValue = 0;
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while (**ptr)
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{
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hexValue = hex(**ptr);
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if (hexValue >=0)
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{
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*intValue = (*intValue <<4) | hexValue;
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numChars ++;
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}
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else
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break;
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(*ptr)++;
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}
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return (numChars);
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}
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/*
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* This function does all command procesing for interfacing to gdb.
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*/
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void handle_exception(int exceptionVector)
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{
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int sigval;
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int addr, length;
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char * ptr;
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int newPC;
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Frame *frame;
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if (remote_debug) printf("\nHANDLE_EXCEPTION: vector=%d, sr=0x%x, pc=0x%x, sp=0x%x\n",
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exceptionVector,
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registers[ PS ],
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registers[ PC ],
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registers[ A7 ]
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); fflush (stdout);
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/* reply to host that an exception has occurred */
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sigval = computeSignal( exceptionVector );
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remcomOutBuffer[0] = 'S';
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remcomOutBuffer[1] = hexchars[sigval >> 4];
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remcomOutBuffer[2] = hexchars[sigval % 16];
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remcomOutBuffer[3] = 0;
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putpacket(remcomOutBuffer);
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while (1==1) {
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error = 0;
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remcomOutBuffer[0] = 0;
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getpacket(remcomInBuffer);
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switch (remcomInBuffer[0]) {
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case '?' : remcomOutBuffer[0] = 'S';
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remcomOutBuffer[1] = hexchars[sigval >> 4];
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remcomOutBuffer[2] = hexchars[sigval % 16];
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remcomOutBuffer[3] = 0;
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break;
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case 'd' : remote_debug = !(remote_debug); /* toggle debug flag */
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break;
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case 'g' : /* return the value of the CPU registers */
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mem2hex((char*) registers, remcomOutBuffer, NUMREGBYTES);
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break;
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case 'G' : /* set the value of the CPU registers - return OK */
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hex2mem(&remcomInBuffer[1], (char*) registers, NUMREGBYTES);
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strcpy(remcomOutBuffer,"OK");
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break;
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/* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
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case 'm' :
|
|
if (setjmp(remcomEnv) == 0)
|
|
{
|
|
exceptionHandler(2,handle_buserror);
|
|
|
|
/* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */
|
|
ptr = &remcomInBuffer[1];
|
|
if (hexToInt(&ptr,&addr))
|
|
if (*(ptr++) == ',')
|
|
if (hexToInt(&ptr,&length))
|
|
{
|
|
ptr = 0;
|
|
mem2hex((char*) addr, remcomOutBuffer, length);
|
|
}
|
|
|
|
if (ptr)
|
|
{
|
|
strcpy(remcomOutBuffer,"E01");
|
|
debug_error("malformed read memory command: %s",remcomInBuffer);
|
|
}
|
|
}
|
|
else {
|
|
exceptionHandler(2,_catchException);
|
|
strcpy(remcomOutBuffer,"E03");
|
|
debug_error("bus error");
|
|
}
|
|
|
|
/* restore handler for bus error */
|
|
exceptionHandler(2,_catchException);
|
|
break;
|
|
|
|
/* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
|
|
case 'M' :
|
|
if (setjmp(remcomEnv) == 0) {
|
|
exceptionHandler(2,handle_buserror);
|
|
|
|
/* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */
|
|
ptr = &remcomInBuffer[1];
|
|
if (hexToInt(&ptr,&addr))
|
|
if (*(ptr++) == ',')
|
|
if (hexToInt(&ptr,&length))
|
|
if (*(ptr++) == ':')
|
|
{
|
|
hex2mem(ptr, (char*) addr, length);
|
|
ptr = 0;
|
|
strcpy(remcomOutBuffer,"OK");
|
|
}
|
|
if (ptr)
|
|
{
|
|
strcpy(remcomOutBuffer,"E02");
|
|
debug_error("malformed write memory command: %s",remcomInBuffer);
|
|
}
|
|
}
|
|
else {
|
|
exceptionHandler(2,_catchException);
|
|
strcpy(remcomOutBuffer,"E03");
|
|
debug_error("bus error");
|
|
}
|
|
|
|
/* restore handler for bus error */
|
|
exceptionHandler(2,_catchException);
|
|
break;
|
|
|
|
/* cAA..AA Continue at address AA..AA(optional) */
|
|
/* sAA..AA Step one instruction from AA..AA(optional) */
|
|
case 'c' :
|
|
case 's' :
|
|
/* try to read optional parameter, pc unchanged if no parm */
|
|
ptr = &remcomInBuffer[1];
|
|
if (hexToInt(&ptr,&addr))
|
|
registers[ PC ] = addr;
|
|
|
|
newPC = registers[ PC];
|
|
|
|
/* clear the trace bit */
|
|
registers[ PS ] &= 0x7fff;
|
|
|
|
/* set the trace bit if we're stepping */
|
|
if (remcomInBuffer[0] == 's') registers[ PS ] |= 0x8000;
|
|
|
|
/*
|
|
* look for newPC in the linked list of exception frames.
|
|
* if it is found, use the old frame it. otherwise,
|
|
* fake up a dummy frame in returnFromException().
|
|
*/
|
|
if (remote_debug) printf("new pc = 0x%x\n",newPC);
|
|
frame = lastFrame;
|
|
while (frame)
|
|
{
|
|
if (remote_debug)
|
|
printf("frame at 0x%x has pc=0x%x, except#=%d\n",
|
|
frame,frame->exceptionPC,
|
|
frame->exceptionVector);
|
|
if (frame->exceptionPC == newPC) break; /* bingo! a match */
|
|
/*
|
|
* for a breakpoint instruction, the saved pc may
|
|
* be off by two due to re-executing the instruction
|
|
* replaced by the trap instruction. Check for this.
|
|
*/
|
|
if ((frame->exceptionVector == 33) &&
|
|
(frame->exceptionPC == (newPC+2))) break;
|
|
if (frame == frame->previous)
|
|
{
|
|
frame = 0; /* no match found */
|
|
break;
|
|
}
|
|
frame = frame->previous;
|
|
}
|
|
|
|
/*
|
|
* If we found a match for the PC AND we are not returning
|
|
* as a result of a breakpoint (33),
|
|
* trace exception (9), nmi (31), jmp to
|
|
* the old exception handler as if this code never ran.
|
|
*/
|
|
if (frame)
|
|
{
|
|
if ((frame->exceptionVector != 9) &&
|
|
(frame->exceptionVector != 31) &&
|
|
(frame->exceptionVector != 33))
|
|
{
|
|
/*
|
|
* invoke the previous handler.
|
|
*/
|
|
if (oldExceptionHook)
|
|
(*oldExceptionHook) (frame->exceptionVector);
|
|
newPC = registers[ PC ]; /* pc may have changed */
|
|
if (newPC != frame->exceptionPC)
|
|
{
|
|
if (remote_debug)
|
|
printf("frame at 0x%x has pc=0x%x, except#=%d\n",
|
|
frame,frame->exceptionPC,
|
|
frame->exceptionVector);
|
|
/* re-use the last frame, we're skipping it (longjump?)*/
|
|
frame = (Frame *) 0;
|
|
_returnFromException( frame ); /* this is a jump */
|
|
}
|
|
}
|
|
}
|
|
|
|
/* if we couldn't find a frame, create one */
|
|
if (frame == 0)
|
|
{
|
|
frame = lastFrame -1 ;
|
|
|
|
/* by using a bunch of print commands with breakpoints,
|
|
it's possible for the frame stack to creep down. If it creeps
|
|
too far, give up and reset it to the top. Normal use should
|
|
not see this happen.
|
|
*/
|
|
if ((unsigned int) (frame-2) < (unsigned int) &gdbFrameStack)
|
|
{
|
|
initializeRemcomErrorFrame();
|
|
frame = lastFrame;
|
|
}
|
|
frame->previous = lastFrame;
|
|
lastFrame = frame;
|
|
frame = 0; /* null so _return... will properly initialize it */
|
|
}
|
|
|
|
_returnFromException( frame ); /* this is a jump */
|
|
|
|
break;
|
|
|
|
/* kill the program */
|
|
case 'k' : /* do nothing */
|
|
break;
|
|
} /* switch */
|
|
|
|
/* reply to the request */
|
|
putpacket(remcomOutBuffer);
|
|
}
|
|
}
|
|
|
|
|
|
void initializeRemcomErrorFrame()
|
|
{
|
|
lastFrame = ((Frame *) &gdbFrameStack[FRAMESIZE-1]) - 1;
|
|
lastFrame->previous = lastFrame;
|
|
}
|
|
|
|
/* this function is used to set up exception handlers for tracing and
|
|
breakpoints */
|
|
void set_debug_traps()
|
|
{
|
|
extern void _debug_level7();
|
|
extern void remcomHandler();
|
|
int exception;
|
|
|
|
initializeRemcomErrorFrame();
|
|
stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1];
|
|
|
|
setup_vectors();
|
|
|
|
if (oldExceptionHook != remcomHandler)
|
|
{
|
|
oldExceptionHook = exceptionHook;
|
|
exceptionHook = remcomHandler;
|
|
}
|
|
|
|
initialized = 1;
|
|
|
|
}
|
|
/* This function will generate a breakpoint exception. It is used at the
|
|
beginning of a program to sync up with a debugger and can be used
|
|
otherwise as a quick means to stop program execution and "break" into
|
|
the debugger. */
|
|
|
|
void breakpoint()
|
|
{
|
|
if (initialized) BREAKPOINT();
|
|
}
|