gdb/stubs/m68k-stub.c - gdb

Global variables defined

Data types defined

Functions defined

Macros defined

Source code

  1. /****************************************************************************

  3.                 THIS SOFTWARE IS NOT COPYRIGHTED

  5.    HP offers the following for use in the public domain.  HP makes no
  6.    warranty with regard to the software or it's performance and the
  7.    user accepts the software "AS IS" with all faults.

  9.    HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD
  10.    TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  11.    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

  13. ****************************************************************************/

  15. /****************************************************************************
  16. *  Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $
  17. *
  18. *  Module name: remcom.c $
  19. *  Revision: 1.34 $
  20. *  Date: 91/03/09 12:29:49 $
  21. *  Contributor:     Lake Stevens Instrument Division$
  22. *
  23. *  Description:     low level support for gdb debugger. $
  24. *
  25. *  Considerations:  only works on target hardware $
  26. *
  27. *  Written by:      Glenn Engel $
  28. *  ModuleState:     Experimental $
  29. *
  30. *  NOTES:           See Below $
  31. *
  32. *  To enable debugger support, two things need to happen.  One, a
  33. *  call to set_debug_traps() is necessary in order to allow any breakpoints
  34. *  or error conditions to be properly intercepted and reported to gdb.
  35. *  Two, a breakpoint needs to be generated to begin communication.  This
  36. *  is most easily accomplished by a call to breakpoint().  Breakpoint()
  37. *  simulates a breakpoint by executing a trap #1.  The breakpoint instruction
  38. *  is hardwired to trap #1 because not to do so is a compatibility problem--
  39. *  there either should be a standard breakpoint instruction, or the protocol
  40. *  should be extended to provide some means to communicate which breakpoint
  41. *  instruction is in use (or have the stub insert the breakpoint).
  42. *
  43. *  Some explanation is probably necessary to explain how exceptions are
  44. *  handled.  When an exception is encountered the 68000 pushes the current
  45. *  program counter and status register onto the supervisor stack and then
  46. *  transfers execution to a location specified in it's vector table.
  47. *  The handlers for the exception vectors are hardwired to jmp to an address
  48. *  given by the relation:  (exception - 256) * 6.  These are decending
  49. *  addresses starting from -6, -12, -18, ...  By allowing 6 bytes for
  50. *  each entry, a jsr, jmp, bsr, ... can be used to enter the exception
  51. *  handler.  Using a jsr to handle an exception has an added benefit of
  52. *  allowing a single handler to service several exceptions and use the
  53. *  return address as the key differentiation.  The vector number can be
  54. *  computed from the return address by [ exception = (addr + 1530) / 6 ].
  55. *  The sole purpose of the routine _catchException is to compute the
  56. *  exception number and push it on the stack in place of the return address.
  57. *  The external function exceptionHandler() is
  58. *  used to attach a specific handler to a specific m68k exception.
  59. *  For 68020 machines, the ability to have a return address around just
  60. *  so the vector can be determined is not necessary because the '020 pushes an
  61. *  extra word onto the stack containing the vector offset
  62. *
  63. *  Because gdb will sometimes write to the stack area to execute function
  64. *  calls, this program cannot rely on using the supervisor stack so it
  65. *  uses it's own stack area reserved in the int array remcomStack.
  66. *
  67. *************
  68. *
  69. *    The following gdb commands are supported:
  70. *
  71. * command          function                               Return value
  72. *
  73. *    g             return the value of the CPU registers  hex data or ENN
  74. *    G             set the value of the CPU registers     OK or ENN
  75. *
  76. *    mAA..AA,LLLL  Read LLLL bytes at address AA..AA      hex data or ENN
  77. *    MAA..AA,LLLL: Write LLLL bytes at address AA.AA      OK or ENN
  78. *
  79. *    c             Resume at current address              SNN   ( signal NN)
  80. *    cAA..AA       Continue at address AA..AA             SNN
  81. *
  82. *    s             Step one instruction                   SNN
  83. *    sAA..AA       Step one instruction from AA..AA       SNN
  84. *
  85. *    k             kill
  86. *
  87. *    ?             What was the last sigval ?             SNN   (signal NN)
  88. *
  89. * All commands and responses are sent with a packet which includes a
  90. * checksum.  A packet consists of
  91. *
  92. * $<packet info>#<checksum>.
  93. *
  94. * where
  95. * <packet info> :: <characters representing the command or response>
  96. * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
  97. *
  98. * When a packet is received, it is first acknowledged with either '+' or '-'.
  99. * '+' indicates a successful transfer.  '-' indicates a failed transfer.
  100. *
  101. * Example:
  102. *
  103. * Host:                  Reply:
  104. * $m0,10#2a               +$00010203040506070809101112131415#42
  105. *
  106. ****************************************************************************/

  108. #include <stdio.h>
  109. #include <string.h>
  110. #include <setjmp.h>

  112. /************************************************************************
  113. *
  114. * external low-level support routines
  115. */
  116. ‌typedef void (*ExceptionHook)(int);   /* pointer to function with int parm */
  117. ‌typedef void (*Function)();           /* pointer to a function */

  119. extern void putDebugChar();        /* write a single character      */
  120. extern int getDebugChar();        /* read and return a single char */

  122. extern Function exceptionHandler();  /* assign an exception handler */
  123. extern ExceptionHook exceptionHook;  /* hook variable for errors/exceptions */

  125. /************************/
  126. /* FORWARD DECLARATIONS */
  127. /************************/
  128. static void
  129. initializeRemcomErrorFrame ();

  131. /************************************************************************/
  132. /* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/
  133. /* at least NUMREGBYTES*2 are needed for register packets */
  134. ‌#define BUFMAX 400

  136. ‌static char initialized;  /* boolean flag. != 0 means we've been initialized */

  138. ‌int     remote_debug;
  139. /*  debug >  0 prints ill-formed commands in valid packets & checksum errors */

  141. ‌static const char hexchars[]="0123456789abcdef";

  143. /* there are 180 bytes of registers on a 68020 w/68881      */
  144. /* many of the fpa registers are 12 byte (96 bit) registers */
  145. ‌#define NUMREGBYTES 180
  146. ‌enum regnames {D0,D1,D2,D3,D4,D5,D6,D7,
  147.                A0,A1,A2,A3,A4,A5,A6,A7,
  148.                PS,PC,
  149.                FP0,FP1,FP2,FP3,FP4,FP5,FP6,FP7,
  150.                FPCONTROL,FPSTATUS,FPIADDR
  151.               };


  154. /* We keep a whole frame cache here.  "Why?", I hear you cry, "doesn't
  155.    GDB handle that sort of thing?"  Well, yes, I believe the only
  156.    reason for this cache is to save and restore floating point state
  157.    (fsave/frestore).  A cleaner way to do this would be to make the
  158. fsave data part of the registers which GDB deals with like any
  159.    other registers.  This should not be a performance problem if the
  160.    ability to read individual registers is added to the protocol.  */

  162. ‌typedef struct FrameStruct
  163. {
  164.     struct FrameStruct  *previous;
  165.     int       exceptionPC;      /* pc value when this frame created */
  166.     int       exceptionVector;  /* cpu vector causing exception     */
  167.     short     frameSize;        /* size of cpu frame in words       */
  168.     short     sr;               /* for 68000, this not always sr    */
  169.     int       pc;
  170.     short     format;
  171.     int       fsaveHeader;
  172.     int       morejunk[0];        /* exception frame, fp save... */
  173. ‌} Frame;

  175. ‌#define FRAMESIZE 500
  176. ‌int   gdbFrameStack[FRAMESIZE];
  177. ‌static Frame *lastFrame;

  179. /*
  180. * these should not be static cuz they can be used outside this module
  181. */
  182. ‌int registers[NUMREGBYTES/4];
  183. ‌int superStack;

  185. ‌#define STACKSIZE 10000
  186. ‌int remcomStack[STACKSIZE/sizeof(int)];
  187. ‌static int* stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1];

  189. /*
  190. * In many cases, the system will want to continue exception processing
  191. * when a continue command is given.
  192. * oldExceptionHook is a function to invoke in this case.
  193. */

  195. ‌static ExceptionHook oldExceptionHook;

  197. #ifdef mc68020
  198. /* the size of the exception stack on the 68020 varies with the type of
  199. * exception.  The following table is the number of WORDS used
  200. * for each exception format.
  201. */
  202. ‌const short exceptionSize[] = { 4,4,6,4,4,4,4,4,29,10,16,46,12,4,4,4 };
  203. #endif

  205. #ifdef mc68332
  206. ‌static const short exceptionSize[] = { 4,4,6,4,4,4,4,4,4,4,4,4,16,4,4,4 };
  207. #endif

  209. /************* jump buffer used for setjmp/longjmp **************************/
  210. ‌jmp_buf remcomEnv;

  212. /***************************  ASSEMBLY CODE MACROS *************************/
  213. /*                                                                            */

  215. #ifdef __HAVE_68881__
  216. /* do an fsave, then remember the address to begin a restore from */
  217. ‌#define SAVE_FP_REGS()    asm(" fsave   a0@-");                \
  218.                           asm(" fmovemx fp0-fp7,_registers+72");        \
  219.                           asm(" fmoveml fpcr/fpsr/fpi,_registers+168");
  220. ‌#define RESTORE_FP_REGS()                              \
  221. asm("                                                \n\
  222.     fmoveml  _registers+168,fpcr/fpsr/fpi            \n\
  223.     fmovemx  _registers+72,fp0-fp7                   \n\
  224.     cmpl     #-1,a0@     |  skip frestore flag set ? \n\
  225.     beq      skip_frestore                           \n\
  226.     frestore a0@+                                    \n\
  227. skip_frestore:                                       \n\
  228. ");

  230. #else
  231. ‌#define SAVE_FP_REGS()
  232. ‌#define RESTORE_FP_REGS()
  233. #endif /* __HAVE_68881__ */

  235. void return_to_super();
  236. void return_to_user();

  238. asm("
  239. .text
  240. .globl _return_to_super
  241. _return_to_super:
  242.         movel   _registers+60,sp /* get new stack pointer */
  243.         movel   _lastFrame,a0   /* get last frame info  */
  244.         bra     return_to_any

  246. .globl _return_to_user
  247. _return_to_user:
  248.         movel   _registers+60,a0 /* get usp */
  249.         movel   a0,usp           /* set usp */
  250.         movel   _superStack,sp  /* get original stack pointer */

  252. return_to_any:
  253.         movel   _lastFrame,a0   /* get last frame info  */
  254.         movel   a0@+,_lastFrame /* link in previous frame     */
  255.         addql   #8,a0           /* skip over pc, vector#*/
  256.         movew   a0@+,d0         /* get # of words in cpu frame */
  257.         addw    d0,a0           /* point to end of data        */
  258.         addw    d0,a0           /* point to end of data        */
  259.         movel   a0,a1
  260. #
  261. # copy the stack frame
  262.         subql   #1,d0
  263. copyUserLoop:
  264.         movew   a1@-,sp@-
  265.         dbf     d0,copyUserLoop
  266. ");
  267.         RESTORE_FP_REGS()
  268.    asm("   moveml  _registers,d0-d7/a0-a6");
  269.    asm("   rte");  /* pop and go! */

  271. ‌#define DISABLE_INTERRUPTS()   asm("         oriw   #0x0700,sr");
  272. ‌#define BREAKPOINT() asm("   trap #1");

  274. /* this function is called immediately when a level 7 interrupt occurs */
  275. /* if the previous interrupt level was 7 then we're already servicing  */
  276. /* this interrupt and an rte is in order to return to the debugger.    */
  277. /* For the 68000, the offset for sr is 6 due to the jsr return address */
  278. asm("
  279. .text
  280. .globl __debug_level7
  281. __debug_level7:
  282.         movew   d0,sp@-");
  283. #if defined (mc68020) || defined (mc68332)
  284. asm("        movew   sp@(2),d0");
  285. #else
  286. asm("        movew   sp@(6),d0");
  287. #endif
  288. asm("        andiw   #0x700,d0
  289.         cmpiw   #0x700,d0
  290.         beq     _already7
  291.         movew   sp@+,d0
  292.         bra     __catchException
  293. _already7:
  294.         movew   sp@+,d0");
  295. #if !defined (mc68020) && !defined (mc68332)
  296. asm("        lea     sp@(4),sp");     /* pull off 68000 return address */
  297. #endif
  298. asm("        rte");

  300. extern void _catchException ();

  302. #if defined (mc68020) || defined (mc68332)
  303. /* This function is called when a 68020 exception occurs.  It saves
  304. * all the cpu and fpcp regs in the _registers array, creates a frame on a
  305. * linked list of frames which has the cpu and fpcp stack frames needed
  306. * to properly restore the context of these processors, and invokes
  307. * an exception handler (remcom_handler).
  308. *
  309. * stack on entry:                       stack on exit:
  310. *   N bytes of junk                     exception # MSWord
  311. *   Exception Format Word               exception # MSWord
  312. *   Program counter LSWord
  313. *   Program counter MSWord
  314. *   Status Register
  315. *
  316. *
  317. */
  318. asm("
  319. .text
  320. .globl __catchException
  321. __catchException:");
  322. DISABLE_INTERRUPTS();
  323. asm("
  324.         moveml  d0-d7/a0-a6,_registers /* save registers        */
  325.         movel        _lastFrame,a0        /* last frame pointer */
  326. ");
  327. SAVE_FP_REGS();
  328. asm("
  329.         lea     _registers,a5   /* get address of registers     */
  330.         movew   sp@,d1          /* get status register          */
  331.         movew   d1,a5@(66)      /* save sr                         */
  332.         movel   sp@(2),a4       /* save pc in a4 for later use  */
  333.         movel   a4,a5@(68)      /* save pc in _regisers[]              */

  335. #
  336. # figure out how many bytes in the stack frame
  337.         movew   sp@(6),d0        /* get '020 exception format        */
  338.         movew   d0,d2           /* make a copy of format word   */
  339.         andiw   #0xf000,d0      /* mask off format type         */
  340.         rolw    #5,d0           /* rotate into the low byte *2  */
  341.         lea     _exceptionSize,a1
  342.         addw    d0,a1           /* index into the table         */
  343.         movew   a1@,d0          /* get number of words in frame */
  344.         movew   d0,d3           /* save it                      */
  345.         subw    d0,a0                /* adjust save pointer          */
  346.         subw    d0,a0                /* adjust save pointer(bytes)   */
  347.         movel   a0,a1           /* copy save pointer            */
  348.         subql   #1,d0           /* predecrement loop counter    */
  349. #
  350. # copy the frame
  351. saveFrameLoop:
  352.         movew          sp@+,a1@+
  353.         dbf     d0,saveFrameLoop
  354. #
  355. # now that the stack has been clenaed,
  356. # save the a7 in use at time of exception
  357.         movel   sp,_superStack  /* save supervisor sp           */
  358.         andiw   #0x2000,d1      /* were we in supervisor mode ? */
  359.         beq     userMode
  360.         movel   a7,a5@(60)      /* save a7                  */
  361.         bra     a7saveDone
  362. userMode:
  363.         movel   usp,a1
  364.         movel   a1,a5@(60)      /* save user stack pointer        */
  365. a7saveDone:

  367. #
  368. # save size of frame
  369.         movew   d3,a0@-

  371. #
  372. # compute exception number
  373.         andl    #0xfff,d2           /* mask off vector offset        */
  374.         lsrw    #2,d2           /* divide by 4 to get vect num        */
  375.         movel   d2,a0@-         /* save it                      */
  376. #
  377. # save pc causing exception
  378.         movel   a4,a0@-
  379. #
  380. # save old frame link and set the new value
  381.         movel        _lastFrame,a1        /* last frame pointer */
  382.         movel   a1,a0@-                /* save pointer to prev frame        */
  383.         movel   a0,_lastFrame

  385.         movel   d2,sp@-                /* push exception num           */
  386.         movel   _exceptionHook,a0  /* get address of handler */
  387.         jbsr    a0@             /* and call it */
  388.         clrl    sp@             /* replace exception num parm with frame ptr */
  389.         jbsr     __returnFromException   /* jbsr, but never returns */
  390. ");
  391. #else /* mc68000 */
  392. /* This function is called when an exception occurs.  It translates the
  393. * return address found on the stack into an exception vector # which
  394. * is then handled by either handle_exception or a system handler.
  395. * _catchException provides a front end for both.
  396. *
  397. * stack on entry:                       stack on exit:
  398. *   Program counter MSWord              exception # MSWord
  399. *   Program counter LSWord              exception # MSWord
  400. *   Status Register
  401. *   Return Address  MSWord
  402. *   Return Address  LSWord
  403. */
  404. asm("
  405. .text
  406. .globl __catchException
  407. __catchException:");
  408. DISABLE_INTERRUPTS();
  409. asm("
  410.         moveml d0-d7/a0-a6,_registers  /* save registers               */
  411.         movel        _lastFrame,a0        /* last frame pointer */
  412. ");
  413. SAVE_FP_REGS();
  414. asm("
  415.         lea     _registers,a5   /* get address of registers     */
  416.         movel   sp@+,d2         /* pop return address           */
  417.         addl         #1530,d2        /* convert return addr to         */
  418.         divs         #6,d2           /*  exception number                */
  419.         extl    d2

  421.         moveql  #3,d3           /* assume a three word frame     */

  423.         cmpiw   #3,d2           /* bus error or address error ? */
  424.         bgt     normal          /* if >3 then normal error      */
  425.         movel   sp@+,a0@-       /* copy error info to frame buff*/
  426.         movel   sp@+,a0@-       /* these are never used         */
  427.         moveql  #7,d3           /* this is a 7 word frame       */

  429. normal:
  430.         movew   sp@+,d1         /* pop status register          */
  431.         movel   sp@+,a4         /* pop program counter          */
  432.         movew   d1,a5@(66)      /* save sr                         */
  433.         movel   a4,a5@(68)      /* save pc in _regisers[]              */
  434.         movel   a4,a0@-         /* copy pc to frame buffer      */
  435.         movew   d1,a0@-         /* copy sr to frame buffer      */

  437.         movel   sp,_superStack  /* save supervisor sp          */

  439.         andiw   #0x2000,d1      /* were we in supervisor mode ? */
  440.         beq     userMode
  441.         movel   a7,a5@(60)      /* save a7                  */
  442.         bra     saveDone
  443. userMode:
  444.         movel   usp,a1            /* save user stack pointer         */
  445.         movel   a1,a5@(60)      /* save user stack pointer        */
  446. saveDone:

  448.         movew   d3,a0@-         /* push frame size in words     */
  449.         movel   d2,a0@-         /* push vector number           */
  450.         movel   a4,a0@-         /* push exception pc            */

  452. #
  453. # save old frame link and set the new value
  454.         movel        _lastFrame,a1        /* last frame pointer */
  455.         movel   a1,a0@-                /* save pointer to prev frame        */
  456.         movel   a0,_lastFrame

  458.         movel   d2,sp@-                /* push exception num           */
  459.         movel   _exceptionHook,a0  /* get address of handler */
  460.         jbsr    a0@             /* and call it */
  461.         clrl    sp@             /* replace exception num parm with frame ptr */
  462.         jbsr     __returnFromException   /* jbsr, but never returns */
  463. ");
  464. #endif


  467. /*
  468. * remcomHandler is a front end for handle_exception.  It moves the
  469. * stack pointer into an area reserved for debugger use in case the
  470. * breakpoint happened in supervisor mode.
  471. */
  472. asm("_remcomHandler:");
  473. asm("           addl    #4,sp");        /* pop off return address     */
  474. asm("           movel   sp@+,d0");      /* get the exception number   */
  475. asm("                movel   _stackPtr,sp"); /* move to remcom stack area  */
  476. asm("                movel   d0,sp@-");        /* push exception onto stack  */
  477. asm("                jbsr    _handle_exception");    /* this never returns */
  478. asm("           rts");                  /* return */

  480. void
  481. ‌_returnFromException (Frame * frame)
  482. {
  483.   /* if no passed in frame, use the last one */
  484.   if (!frame)
  485.     {
  486.       frame = lastFrame;
  487.       frame->frameSize = 4;
  488.       frame->format = 0;
  489.       frame->fsaveHeader = -1;        /* restore regs, but we dont have fsave info */
  490.     }

  492. #if !defined (mc68020) && !defined (mc68332)
  493.   /* a 68000 cannot use the internal info pushed onto a bus error
  494.    * or address error frame when doing an RTE so don't put this info
  495.    * onto the stack or the stack will creep every time this happens.
  496.    */
  497.   frame->frameSize = 3;
  498. #endif

  500.   /* throw away any frames in the list after this frame */
  501.   lastFrame = frame;

  503.   frame->sr = registers[(int) PS];
  504.   frame->pc = registers[(int) PC];

  506.   if (registers[(int) PS] & 0x2000)
  507.     {
  508.       /* return to supervisor mode... */
  509.       return_to_super ();
  510.     }
  511.   else
  512.     {                                /* return to user mode */
  513.       return_to_user ();
  514.     }
  515. }

  517. int
  518. ‌hex (ch)
  519.      char ch;
  520. {
  521.   if ((ch >= 'a') && (ch <= 'f'))
  522.     return (ch - 'a' + 10);
  523.   if ((ch >= '0') && (ch <= '9'))
  524.     return (ch - '0');
  525.   if ((ch >= 'A') && (ch <= 'F'))
  526.     return (ch - 'A' + 10);
  527.   return (-1);
  528. }

  530. ‌static char remcomInBuffer[BUFMAX];
  531. ‌static char remcomOutBuffer[BUFMAX];

  533. /* scan for the sequence $<data>#<checksum>     */

  535. unsigned char *
  536. ‌getpacket (void)
  537. {
  538.   unsigned char *buffer = &remcomInBuffer[0];
  539.   unsigned char checksum;
  540.   unsigned char xmitcsum;
  541.   int count;
  542.   char ch;

  544.   while (1)
  545.     {
  546.       /* wait around for the start character, ignore all other characters */
  547.       while ((ch = getDebugChar ()) != '$')
  548.         ;

  550.     retry:
  551.       checksum = 0;
  552.       xmitcsum = -1;
  553.       count = 0;

  555.       /* now, read until a # or end of buffer is found */
  556.       while (count < BUFMAX - 1)
  557.         {
  558.           ch = getDebugChar ();
  559.           if (ch == '$')
  560.             goto retry;
  561.           if (ch == '#')
  562.             break;
  563.           checksum = checksum + ch;
  564.           buffer[count] = ch;
  565.           count = count + 1;
  566.         }
  567.       buffer[count] = 0;

  569.       if (ch == '#')
  570.         {
  571.           ch = getDebugChar ();
  572.           xmitcsum = hex (ch) << 4;
  573.           ch = getDebugChar ();
  574.           xmitcsum += hex (ch);

  576.           if (checksum != xmitcsum)
  577.             {
  578.               if (remote_debug)
  579.                 {
  580.                   fprintf (stderr,
  581.                            "bad checksum.  My count = 0x%x, sent=0x%x. buf=%s\n",
  582.                            checksum, xmitcsum, buffer);
  583.                 }
  584.               putDebugChar ('-');        /* failed checksum */
  585.             }
  586.           else
  587.             {
  588.               putDebugChar ('+');        /* successful transfer */

  590.               /* if a sequence char is present, reply the sequence ID */
  591.               if (buffer[2] == ':')
  592.                 {
  593.                   putDebugChar (buffer[0]);
  594.                   putDebugChar (buffer[1]);

  596.                   return &buffer[3];
  597.                 }

  599.               return &buffer[0];
  600.             }
  601.         }
  602.     }
  603. }

  605. /* send the packet in buffer. */

  607. void
  608. ‌putpacket (buffer)
  609.      char *buffer;
  610. {
  611.   unsigned char checksum;
  612.   int count;
  613.   char ch;

  615.   /*  $<packet info>#<checksum>. */
  616.   do
  617.     {
  618.       putDebugChar ('$');
  619.       checksum = 0;
  620.       count = 0;

  622.       while (ch = buffer[count])
  623.         {
  624.           putDebugChar (ch);
  625.           checksum += ch;
  626.           count += 1;
  627.         }

  629.       putDebugChar ('#');
  630.       putDebugChar (hexchars[checksum >> 4]);
  631.       putDebugChar (hexchars[checksum % 16]);

  633.     }
  634.   while (getDebugChar () != '+');

  636. }

  638. void
  639. ‌debug_error (format, parm)
  640.      char *format;
  641.      char *parm;
  642. {
  643.   if (remote_debug)
  644.     fprintf (stderr, format, parm);
  645. }

  647. /* convert the memory pointed to by mem into hex, placing result in buf */
  648. /* return a pointer to the last char put in buf (null) */
  649. char *
  650. ‌mem2hex (mem, buf, count)
  651.      char *mem;
  652.      char *buf;
  653.      int count;
  654. {
  655.   int i;
  656.   unsigned char ch;
  657.   for (i = 0; i < count; i++)
  658.     {
  659.       ch = *mem++;
  660.       *buf++ = hexchars[ch >> 4];
  661.       *buf++ = hexchars[ch % 16];
  662.     }
  663.   *buf = 0;
  664.   return (buf);
  665. }

  667. /* convert the hex array pointed to by buf into binary to be placed in mem */
  668. /* return a pointer to the character AFTER the last byte written */
  669. char *
  670. ‌hex2mem (buf, mem, count)
  671.      char *buf;
  672.      char *mem;
  673.      int count;
  674. {
  675.   int i;
  676.   unsigned char ch;
  677.   for (i = 0; i < count; i++)
  678.     {
  679.       ch = hex (*buf++) << 4;
  680.       ch = ch + hex (*buf++);
  681.       *mem++ = ch;
  682.     }
  683.   return (mem);
  684. }

  686. /* a bus error has occurred, perform a longjmp
  687.    to return execution and allow handling of the error */

  689. void
  690. ‌handle_buserror ()
  691. {
  692.   longjmp (remcomEnv, 1);
  693. }

  695. /* this function takes the 68000 exception number and attempts to
  696.    translate this number into a unix compatible signal value */
  697. int
  698. ‌computeSignal (exceptionVector)
  699.      int exceptionVector;
  700. {
  701.   int sigval;
  702.   switch (exceptionVector)
  703.     {
  704.     case 2:
  705.       sigval = 10;
  706.       break;                        /* bus error           */
  707.     case 3:
  708.       sigval = 10;
  709.       break;                        /* address error       */
  710.     case 4:
  711.       sigval = 4;
  712.       break;                        /* illegal instruction */
  713.     case 5:
  714.       sigval = 8;
  715.       break;                        /* zero divide         */
  716.     case 6:
  717.       sigval = 8;
  718.       break;                        /* chk instruction     */
  719.     case 7:
  720.       sigval = 8;
  721.       break;                        /* trapv instruction   */
  722.     case 8:
  723.       sigval = 11;
  724.       break;                        /* privilege violation */
  725.     case 9:
  726.       sigval = 5;
  727.       break;                        /* trace trap          */
  728.     case 10:
  729.       sigval = 4;
  730.       break;                        /* line 1010 emulator  */
  731.     case 11:
  732.       sigval = 4;
  733.       break;                        /* line 1111 emulator  */

  735.       /* Coprocessor protocol violation.  Using a standard MMU or FPU
  736.          this cannot be triggered by software.  Call it a SIGBUS.  */
  737.     case 13:
  738.       sigval = 10;
  739.       break;

  741.     case 31:
  742.       sigval = 2;
  743.       break;                        /* interrupt           */
  744.     case 33:
  745.       sigval = 5;
  746.       break;                        /* breakpoint          */

  748.       /* This is a trap #8 instruction.  Apparently it is someone's software
  749.          convention for some sort of SIGFPE condition.  Whose?  How many
  750.          people are being screwed by having this code the way it is?
  751.          Is there a clean solution?  */
  752.     case 40:
  753.       sigval = 8;
  754.       break;                        /* floating point err  */

  756.     case 48:
  757.       sigval = 8;
  758.       break;                        /* floating point err  */
  759.     case 49:
  760.       sigval = 8;
  761.       break;                        /* floating point err  */
  762.     case 50:
  763.       sigval = 8;
  764.       break;                        /* zero divide         */
  765.     case 51:
  766.       sigval = 8;
  767.       break;                        /* underflow           */
  768.     case 52:
  769.       sigval = 8;
  770.       break;                        /* operand error       */
  771.     case 53:
  772.       sigval = 8;
  773.       break;                        /* overflow            */
  774.     case 54:
  775.       sigval = 8;
  776.       break;                        /* NAN                 */
  777.     default:
  778.       sigval = 7;                /* "software generated" */
  779.     }
  780.   return (sigval);
  781. }

  783. /**********************************************/
  784. /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */
  785. /* RETURN NUMBER OF CHARS PROCESSED           */
  786. /**********************************************/
  787. int
  788. ‌hexToInt (char **ptr, int *intValue)
  789. {
  790.   int numChars = 0;
  791.   int hexValue;

  793.   *intValue = 0;

  795.   while (**ptr)
  796.     {
  797.       hexValue = hex (**ptr);
  798.       if (hexValue >= 0)
  799.         {
  800.           *intValue = (*intValue << 4) | hexValue;
  801.           numChars++;
  802.         }
  803.       else
  804.         break;

  806.       (*ptr)++;
  807.     }

  809.   return (numChars);
  810. }

  812. /*
  813. * This function does all command procesing for interfacing to gdb.
  814. */
  815. void
  816. ‌handle_exception (int exceptionVector)
  817. {
  818.   int sigval, stepping;
  819.   int addr, length;
  820.   char *ptr;
  821.   int newPC;
  822.   Frame *frame;

  824.   if (remote_debug)
  825.     printf ("vector=%d, sr=0x%x, pc=0x%x\n",
  826.             exceptionVector, registers[PS], registers[PC]);

  828.   /* reply to host that an exception has occurred */
  829.   sigval = computeSignal (exceptionVector);
  830.   remcomOutBuffer[0] = 'S';
  831.   remcomOutBuffer[1] = hexchars[sigval >> 4];
  832.   remcomOutBuffer[2] = hexchars[sigval % 16];
  833.   remcomOutBuffer[3] = 0;

  835.   putpacket (remcomOutBuffer);

  837.   stepping = 0;

  839.   while (1 == 1)
  840.     {
  841.       remcomOutBuffer[0] = 0;
  842.       ptr = getpacket ();
  843.       switch (*ptr++)
  844.         {
  845.         case '?':
  846.           remcomOutBuffer[0] = 'S';
  847.           remcomOutBuffer[1] = hexchars[sigval >> 4];
  848.           remcomOutBuffer[2] = hexchars[sigval % 16];
  849.           remcomOutBuffer[3] = 0;
  850.           break;
  851.         case 'd':
  852.           remote_debug = !(remote_debug);        /* toggle debug flag */
  853.           break;
  854.         case 'g':                /* return the value of the CPU registers */
  855.           mem2hex ((char *) registers, remcomOutBuffer, NUMREGBYTES);
  856.           break;
  857.         case 'G':                /* set the value of the CPU registers - return OK */
  858.           hex2mem (ptr, (char *) registers, NUMREGBYTES);
  859.           strcpy (remcomOutBuffer, "OK");
  860.           break;

  862.           /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
  863.         case 'm':
  864.           if (setjmp (remcomEnv) == 0)
  865.             {
  866.               exceptionHandler (2, handle_buserror);

  868.               /* TRY TO READ %x,%x.  IF SUCCEED, SET PTR = 0 */
  869.               if (hexToInt (&ptr, &addr))
  870.                 if (*(ptr++) == ',')
  871.                   if (hexToInt (&ptr, &length))
  872.                     {
  873.                       ptr = 0;
  874.                       mem2hex ((char *) addr, remcomOutBuffer, length);
  875.                     }

  877.               if (ptr)
  878.                 {
  879.                   strcpy (remcomOutBuffer, "E01");
  880.                 }
  881.             }
  882.           else
  883.             {
  884.               exceptionHandler (2, _catchException);
  885.               strcpy (remcomOutBuffer, "E03");
  886.               debug_error ("bus error");
  887.             }

  889.           /* restore handler for bus error */
  890.           exceptionHandler (2, _catchException);
  891.           break;

  893.           /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
  894.         case 'M':
  895.           if (setjmp (remcomEnv) == 0)
  896.             {
  897.               exceptionHandler (2, handle_buserror);

  899.               /* TRY TO READ '%x,%x:'.  IF SUCCEED, SET PTR = 0 */
  900.               if (hexToInt (&ptr, &addr))
  901.                 if (*(ptr++) == ',')
  902.                   if (hexToInt (&ptr, &length))
  903.                     if (*(ptr++) == ':')
  904.                       {
  905.                         hex2mem (ptr, (char *) addr, length);
  906.                         ptr = 0;
  907.                         strcpy (remcomOutBuffer, "OK");
  908.                       }
  909.               if (ptr)
  910.                 {
  911.                   strcpy (remcomOutBuffer, "E02");
  912.                 }
  913.             }
  914.           else
  915.             {
  916.               exceptionHandler (2, _catchException);
  917.               strcpy (remcomOutBuffer, "E03");
  918.               debug_error ("bus error");
  919.             }

  921.           /* restore handler for bus error */
  922.           exceptionHandler (2, _catchException);
  923.           break;

  925.           /* cAA..AA    Continue at address AA..AA(optional) */
  926.           /* sAA..AA   Step one instruction from AA..AA(optional) */
  927.         case 's':
  928.           stepping = 1;
  929.         case 'c':
  930.           /* try to read optional parameter, pc unchanged if no parm */
  931.           if (hexToInt (&ptr, &addr))
  932.             registers[PC] = addr;

  934.           newPC = registers[PC];

  936.           /* clear the trace bit */
  937.           registers[PS] &= 0x7fff;

  939.           /* set the trace bit if we're stepping */
  940.           if (stepping)
  941.             registers[PS] |= 0x8000;

  943.           /*
  944.            * look for newPC in the linked list of exception frames.
  945.            * if it is found, use the old frame it.  otherwise,
  946.            * fake up a dummy frame in returnFromException().
  947.            */
  948.           if (remote_debug)
  949.             printf ("new pc = 0x%x\n", newPC);
  950.           frame = lastFrame;
  951.           while (frame)
  952.             {
  953.               if (remote_debug)
  954.                 printf ("frame at 0x%x has pc=0x%x, except#=%d\n",
  955.                         frame, frame->exceptionPC, frame->exceptionVector);
  956.               if (frame->exceptionPC == newPC)
  957.                 break;                /* bingo! a match */
  958.               /*
  959.                * for a breakpoint instruction, the saved pc may
  960.                * be off by two due to re-executing the instruction
  961.                * replaced by the trap instruction.  Check for this.
  962.                */
  963.               if ((frame->exceptionVector == 33) &&
  964.                   (frame->exceptionPC == (newPC + 2)))
  965.                 break;
  966.               if (frame == frame->previous)
  967.                 {
  968.                   frame = 0;        /* no match found */
  969.                   break;
  970.                 }
  971.               frame = frame->previous;
  972.             }

  974.           /*
  975.            * If we found a match for the PC AND we are not returning
  976.            * as a result of a breakpoint (33),
  977.            * trace exception (9), nmi (31), jmp to
  978.            * the old exception handler as if this code never ran.
  979.            */
  980.           if (frame)
  981.             {
  982.               if ((frame->exceptionVector != 9) &&
  983.                   (frame->exceptionVector != 31) &&
  984.                   (frame->exceptionVector != 33))
  985.                 {
  986.                   /*
  987.                    * invoke the previous handler.
  988.                    */
  989.                   if (oldExceptionHook)
  990.                     (*oldExceptionHook) (frame->exceptionVector);
  991.                   newPC = registers[PC];        /* pc may have changed  */
  992.                   if (newPC != frame->exceptionPC)
  993.                     {
  994.                       if (remote_debug)
  995.                         printf ("frame at 0x%x has pc=0x%x, except#=%d\n",
  996.                                 frame, frame->exceptionPC,
  997.                                 frame->exceptionVector);
  998.                       /* re-use the last frame, we're skipping it (longjump?) */
  999.                       frame = (Frame *) 0;
  1000.                       _returnFromException (frame);        /* this is a jump */
  1001.                     }
  1002.                 }
  1003.             }

  1005.           /* if we couldn't find a frame, create one */
  1006.           if (frame == 0)
  1007.             {
  1008.               frame = lastFrame - 1;

  1010.               /* by using a bunch of print commands with breakpoints,
  1011.                  it's possible for the frame stack to creep down.  If it creeps
  1012.                  too far, give up and reset it to the top.  Normal use should
  1013.                  not see this happen.
  1014.                */
  1015.               if ((unsigned int) (frame - 2) < (unsigned int) &gdbFrameStack)
  1016.                 {
  1017.                   initializeRemcomErrorFrame ();
  1018.                   frame = lastFrame;
  1019.                 }
  1020.               frame->previous = lastFrame;
  1021.               lastFrame = frame;
  1022.               frame = 0;        /* null so _return... will properly initialize it */
  1023.             }

  1025.           _returnFromException (frame);        /* this is a jump */

  1027.           break;

  1029.           /* kill the program */
  1030.         case 'k':                /* do nothing */
  1031.           break;
  1032.         }                        /* switch */

  1034.       /* reply to the request */
  1035.       putpacket (remcomOutBuffer);
  1036.     }
  1037. }


  1040. void
  1041. ‌initializeRemcomErrorFrame (void)
  1042. {
  1043.   lastFrame = ((Frame *) & gdbFrameStack[FRAMESIZE - 1]) - 1;
  1044.   lastFrame->previous = lastFrame;
  1045. }

  1047. /* this function is used to set up exception handlers for tracing and
  1048.    breakpoints */
  1049. void
  1050. ‌set_debug_traps ()
  1051. {
  1052.   extern void _debug_level7 ();
  1053.   extern void remcomHandler ();
  1054.   int exception;

  1056.   initializeRemcomErrorFrame ();
  1057.   stackPtr = &remcomStack[STACKSIZE / sizeof (int) - 1];

  1059.   for (exception = 2; exception <= 23; exception++)
  1060.     exceptionHandler (exception, _catchException);

  1062.   /* level 7 interrupt              */
  1063.   exceptionHandler (31, _debug_level7);

  1065.   /* breakpoint exception (trap #1) */
  1066.   exceptionHandler (33, _catchException);

  1068.   /* This is a trap #8 instruction.  Apparently it is someone's software
  1069.      convention for some sort of SIGFPE condition.  Whose?  How many
  1070.      people are being screwed by having this code the way it is?
  1071.      Is there a clean solution?  */
  1072.   exceptionHandler (40, _catchException);

  1074.   /* 48 to 54 are floating point coprocessor errors */
  1075.   for (exception = 48; exception <= 54; exception++)
  1076.     exceptionHandler (exception, _catchException);

  1078.   if (oldExceptionHook != remcomHandler)
  1079.     {
  1080.       oldExceptionHook = exceptionHook;
  1081.       exceptionHook = remcomHandler;
  1082.     }

  1084.   initialized = 1;

  1086. }

  1088. /* This function will generate a breakpoint exception.  It is used at the
  1089.    beginning of a program to sync up with a debugger and can be used
  1090.    otherwise as a quick means to stop program execution and "break" into
  1091.    the debugger. */

  1093. void
  1094. ‌breakpoint ()
  1095. {
  1096.   if (initialized)
  1097.     BREAKPOINT ();
  1098. }