gdb/stubs/sparc-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. *  Modified for SPARC by Stu Grossman, Cygnus Support.
  33. *
  34. *  This code has been extensively tested on the Fujitsu SPARClite demo board.
  35. *
  36. *  To enable debugger support, two things need to happen.  One, a
  37. *  call to set_debug_traps() is necessary in order to allow any breakpoints
  38. *  or error conditions to be properly intercepted and reported to gdb.
  39. *  Two, a breakpoint needs to be generated to begin communication.  This
  40. *  is most easily accomplished by a call to breakpoint().  Breakpoint()
  41. *  simulates a breakpoint by executing a trap #1.
  42. *
  43. *************
  44. *
  45. *    The following gdb commands are supported:
  46. *
  47. * command          function                               Return value
  48. *
  49. *    g             return the value of the CPU registers  hex data or ENN
  50. *    G             set the value of the CPU registers     OK or ENN
  51. *
  52. *    mAA..AA,LLLL  Read LLLL bytes at address AA..AA      hex data or ENN
  53. *    MAA..AA,LLLL: Write LLLL bytes at address AA.AA      OK or ENN
  54. *
  55. *    c             Resume at current address              SNN   ( signal NN)
  56. *    cAA..AA       Continue at address AA..AA             SNN
  57. *
  58. *    s             Step one instruction                   SNN
  59. *    sAA..AA       Step one instruction from AA..AA       SNN
  60. *
  61. *    k             kill
  62. *
  63. *    ?             What was the last sigval ?             SNN   (signal NN)
  64. *
  65. * All commands and responses are sent with a packet which includes a
  66. * checksum.  A packet consists of
  67. *
  68. * $<packet info>#<checksum>.
  69. *
  70. * where
  71. * <packet info> :: <characters representing the command or response>
  72. * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
  73. *
  74. * When a packet is received, it is first acknowledged with either '+' or '-'.
  75. * '+' indicates a successful transfer.  '-' indicates a failed transfer.
  76. *
  77. * Example:
  78. *
  79. * Host:                  Reply:
  80. * $m0,10#2a               +$00010203040506070809101112131415#42
  81. *
  82. ****************************************************************************/

  84. #include <string.h>
  85. #include <signal.h>

  87. /************************************************************************
  88. *
  89. * external low-level support routines
  90. */

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

  95. /************************************************************************/
  96. /* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/
  97. /* at least NUMREGBYTES*2 are needed for register packets */
  98. ‌#define BUFMAX 2048

  100. ‌static int initialized = 0;        /* !0 means we've been initialized */

  102. static void set_mem_fault_trap();

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

  106. ‌#define NUMREGS 72

  108. /* Number of bytes of registers.  */
  109. ‌#define NUMREGBYTES (NUMREGS * 4)
  110. ‌enum regnames {G0, G1, G2, G3, G4, G5, G6, G7,
  111.                  O0, O1, O2, O3, O4, O5, SP, O7,
  112.                  L0, L1, L2, L3, L4, L5, L6, L7,
  113.                  I0, I1, I2, I3, I4, I5, FP, I7,

  115.                  F0, F1, F2, F3, F4, F5, F6, F7,
  116.                  F8, F9, F10, F11, F12, F13, F14, F15,
  117.                  F16, F17, F18, F19, F20, F21, F22, F23,
  118.                  F24, F25, F26, F27, F28, F29, F30, F31,
  119.                  Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR };

  121. /***************************  ASSEMBLY CODE MACROS *************************/
  122. /*                                                                            */

  124. extern void trap_low();

  126. asm("
  127.         .reserve trapstack, 1000 * 4, \"bss\", 8

  129.         .data
  130.         .align        4

  132. in_trap_handler:
  133.         .word        0

  135.         .text
  136.         .align 4

  138. ! This function is called when any SPARC trap (except window overflow or
  139. ! underflow) occurs.  It makes sure that the invalid register window is still
  140. ! available before jumping into C code.  It will also restore the world if you
  141. ! return from handle_exception.

  143.         .globl _trap_low
  144. _trap_low:
  145.         mov        %psr, %l0
  146.         mov        %wim, %l3

  148.         srl        %l3, %l0, %l4                ! wim >> cwp
  149.         cmp        %l4, 1
  150.         bne        window_fine                ! Branch if not in the invalid window
  151.         nop

  153. ! Handle window overflow

  155.         mov        %g1, %l4                ! Save g1, we use it to hold the wim
  156.         srl        %l3, 1, %g1                ! Rotate wim right
  157.         tst        %g1
  158.         bg        good_wim                ! Branch if new wim is non-zero
  159.         nop

  161. ! At this point, we need to bring a 1 into the high order bit of the wim.
  162. ! Since we don't want to make any assumptions about the number of register
  163. ! windows, we figure it out dynamically so as to setup the wim correctly.

  165.         not        %g1                        ! Fill g1 with ones
  166.         mov        %g1, %wim                ! Fill the wim with ones
  167.         nop
  168.         nop
  169.         nop
  170.         mov        %wim, %g1                ! Read back the wim
  171.         inc        %g1                        ! Now g1 has 1 just to left of wim
  172.         srl        %g1, 1, %g1                ! Now put 1 at top of wim
  173.         mov        %g0, %wim                ! Clear wim so that subsequent save
  174.         nop                                !  won't trap
  175.         nop
  176.         nop

  178. good_wim:
  179.         save        %g0, %g0, %g0                ! Slip into next window
  180.         mov        %g1, %wim                ! Install the new wim

  182.         std        %l0, [%sp + 0 * 4]        ! save L & I registers
  183.         std        %l2, [%sp + 2 * 4]
  184.         std        %l4, [%sp + 4 * 4]
  185.         std        %l6, [%sp + 6 * 4]

  187.         std        %i0, [%sp + 8 * 4]
  188.         std        %i2, [%sp + 10 * 4]
  189.         std        %i4, [%sp + 12 * 4]
  190.         std        %i6, [%sp + 14 * 4]

  192.         restore                                ! Go back to trap window.
  193.         mov        %l4, %g1                ! Restore %g1

  195. window_fine:
  196.         sethi        %hi(in_trap_handler), %l4
  197.         ld        [%lo(in_trap_handler) + %l4], %l5
  198.         tst        %l5
  199.         bg        recursive_trap
  200.         inc        %l5

  202.         set        trapstack+1000*4, %sp        ! Switch to trap stack

  204. recursive_trap:
  205.         st        %l5, [%lo(in_trap_handler) + %l4]
  206.         sub        %sp,(16+1+6+1+72)*4,%sp        ! Make room for input & locals
  207.                                          ! + hidden arg + arg spill
  208.                                         ! + doubleword alignment
  209.                                         ! + registers[72] local var

  211.         std        %g0, [%sp + (24 + 0) * 4] ! registers[Gx]
  212.         std        %g2, [%sp + (24 + 2) * 4]
  213.         std        %g4, [%sp + (24 + 4) * 4]
  214.         std        %g6, [%sp + (24 + 6) * 4]

  216.         std        %i0, [%sp + (24 + 8) * 4] ! registers[Ox]
  217.         std        %i2, [%sp + (24 + 10) * 4]
  218.         std        %i4, [%sp + (24 + 12) * 4]
  219.         std        %i6, [%sp + (24 + 14) * 4]
  220.                                         ! F0->F31 not implemented
  221.         mov        %y, %l4
  222.         mov        %tbr, %l5
  223.         st        %l4, [%sp + (24 + 64) * 4] ! Y
  224.         st        %l0, [%sp + (24 + 65) * 4] ! PSR
  225.         st        %l3, [%sp + (24 + 66) * 4] ! WIM
  226.         st        %l5, [%sp + (24 + 67) * 4] ! TBR
  227.         st        %l1, [%sp + (24 + 68) * 4] ! PC
  228.         st        %l2, [%sp + (24 + 69) * 4] ! NPC

  230.                                         ! CPSR and FPSR not impl

  232.         or        %l0, 0xf20, %l4
  233.         mov        %l4, %psr                ! Turn on traps, disable interrupts

  235.         call        _handle_exception
  236.         add        %sp, 24 * 4, %o0        ! Pass address of registers

  238. ! Reload all of the registers that aren't on the stack

  240.         ld        [%sp + (24 + 1) * 4], %g1 ! registers[Gx]
  241.         ldd        [%sp + (24 + 2) * 4], %g2
  242.         ldd        [%sp + (24 + 4) * 4], %g4
  243.         ldd        [%sp + (24 + 6) * 4], %g6

  245.         ldd        [%sp + (24 + 8) * 4], %i0 ! registers[Ox]
  246.         ldd        [%sp + (24 + 10) * 4], %i2
  247.         ldd        [%sp + (24 + 12) * 4], %i4
  248.         ldd        [%sp + (24 + 14) * 4], %i6

  250.         ldd        [%sp + (24 + 64) * 4], %l0 ! Y & PSR
  251.         ldd        [%sp + (24 + 68) * 4], %l2 ! PC & NPC

  253.         restore                                ! Ensure that previous window is valid
  254.         save        %g0, %g0, %g0                !  by causing a window_underflow trap

  256.         mov        %l0, %y
  257.         mov        %l1, %psr                ! Make sure that traps are disabled
  258.                                         ! for rett

  260.         sethi        %hi(in_trap_handler), %l4
  261.         ld        [%lo(in_trap_handler) + %l4], %l5
  262.         dec        %l5
  263.         st        %l5, [%lo(in_trap_handler) + %l4]

  265.         jmpl        %l2, %g0                ! Restore old PC
  266.         rett        %l3                        ! Restore old nPC
  267. ");

  269. /* Convert ch from a hex digit to an int */

  271. static int
  272. ‌hex (unsigned char ch)
  273. {
  274.   if (ch >= 'a' && ch <= 'f')
  275.     return ch-'a'+10;
  276.   if (ch >= '0' && ch <= '9')
  277.     return ch-'0';
  278.   if (ch >= 'A' && ch <= 'F')
  279.     return ch-'A'+10;
  280.   return -1;
  281. }

  283. ‌static char remcomInBuffer[BUFMAX];
  284. ‌static char remcomOutBuffer[BUFMAX];

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

  288. unsigned char *
  289. ‌getpacket (void)
  290. {
  291.   unsigned char *buffer = &remcomInBuffer[0];
  292.   unsigned char checksum;
  293.   unsigned char xmitcsum;
  294.   int count;
  295.   char ch;

  297.   while (1)
  298.     {
  299.       /* wait around for the start character, ignore all other characters */
  300.       while ((ch = getDebugChar ()) != '$')
  301.         ;

  303. retry:
  304.       checksum = 0;
  305.       xmitcsum = -1;
  306.       count = 0;

  308.       /* now, read until a # or end of buffer is found */
  309.       while (count < BUFMAX - 1)
  310.         {
  311.           ch = getDebugChar ();
  312.           if (ch == '$')
  313.             goto retry;
  314.           if (ch == '#')
  315.             break;
  316.           checksum = checksum + ch;
  317.           buffer[count] = ch;
  318.           count = count + 1;
  319.         }
  320.       buffer[count] = 0;

  322.       if (ch == '#')
  323.         {
  324.           ch = getDebugChar ();
  325.           xmitcsum = hex (ch) << 4;
  326.           ch = getDebugChar ();
  327.           xmitcsum += hex (ch);

  329.           if (checksum != xmitcsum)
  330.             {
  331.               putDebugChar ('-');        /* failed checksum */
  332.             }
  333.           else
  334.             {
  335.               putDebugChar ('+');        /* successful transfer */

  337.               /* if a sequence char is present, reply the sequence ID */
  338.               if (buffer[2] == ':')
  339.                 {
  340.                   putDebugChar (buffer[0]);
  341.                   putDebugChar (buffer[1]);

  343.                   return &buffer[3];
  344.                 }

  346.               return &buffer[0];
  347.             }
  348.         }
  349.     }
  350. }

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

  354. static void
  355. ‌putpacket (unsigned char *buffer)
  356. {
  357.   unsigned char checksum;
  358.   int count;
  359.   unsigned char ch;

  361.   /*  $<packet info>#<checksum>. */
  362.   do
  363.     {
  364.       putDebugChar('$');
  365.       checksum = 0;
  366.       count = 0;

  368.       while (ch = buffer[count])
  369.         {
  370.           putDebugChar(ch);
  371.           checksum += ch;
  372.           count += 1;
  373.         }

  375.       putDebugChar('#');
  376.       putDebugChar(hexchars[checksum >> 4]);
  377.       putDebugChar(hexchars[checksum & 0xf]);

  379.     }
  380.   while (getDebugChar() != '+');
  381. }

  383. /* Indicate to caller of mem2hex or hex2mem that there has been an
  384.    error.  */
  385. ‌static volatile int mem_err = 0;

  387. /* Convert the memory pointed to by mem into hex, placing result in buf.
  388. * Return a pointer to the last char put in buf (null), in case of mem fault,
  389. * return 0.
  390. * If MAY_FAULT is non-zero, then we will handle memory faults by returning
  391. * a 0, else treat a fault like any other fault in the stub.
  392. */

  394. static unsigned char *
  395. ‌mem2hex (unsigned char *mem, unsigned char *buf, int count, int may_fault)
  396. {
  397.   unsigned char ch;

  399.   set_mem_fault_trap(may_fault);

  401.   while (count-- > 0)
  402.     {
  403.       ch = *mem++;
  404.       if (mem_err)
  405.         return 0;
  406.       *buf++ = hexchars[ch >> 4];
  407.       *buf++ = hexchars[ch & 0xf];
  408.     }

  410.   *buf = 0;

  412.   set_mem_fault_trap(0);

  414.   return buf;
  415. }

  417. /* convert the hex array pointed to by buf into binary to be placed in mem
  418. * return a pointer to the character AFTER the last byte written */

  420. static char *
  421. ‌hex2mem (unsigned char *buf, unsigned char *mem, int count, int may_fault)
  422. {
  423.   int i;
  424.   unsigned char ch;

  426.   set_mem_fault_trap(may_fault);

  428.   for (i=0; i<count; i++)
  429.     {
  430.       ch = hex(*buf++) << 4;
  431.       ch |= hex(*buf++);
  432.       *mem++ = ch;
  433.       if (mem_err)
  434.         return 0;
  435.     }

  437.   set_mem_fault_trap(0);

  439.   return mem;
  440. }

  442. /* This table contains the mapping between SPARC hardware trap types, and
  443.    signals, which are primarily what GDB understands.  It also indicates
  444.    which hardware traps we need to commandeer when initializing the stub. */

  446. ‌static struct hard_trap_info
  447. {
  448.   unsigned char tt;                /* Trap type code for SPARClite */
  449.   unsigned char signo;                /* Signal that we map this trap into */
  450. ‌} hard_trap_info[] = {
  451.   {1, SIGSEGV},                        /* instruction access error */
  452.   {2, SIGILL},                        /* privileged instruction */
  453.   {3, SIGILL},                        /* illegal instruction */
  454.   {4, SIGEMT},                        /* fp disabled */
  455.   {36, SIGEMT},                        /* cp disabled */
  456.   {7, SIGBUS},                        /* mem address not aligned */
  457.   {9, SIGSEGV},                        /* data access exception */
  458.   {10, SIGEMT},                        /* tag overflow */
  459.   {128+1, SIGTRAP},                /* ta 1 - normal breakpoint instruction */
  460.   {0, 0}                        /* Must be last */
  461. };

  463. /* Set up exception handlers for tracing and breakpoints */

  465. void
  466. ‌set_debug_traps (void)
  467. {
  468.   struct hard_trap_info *ht;

  470.   for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  471.     exceptionHandler(ht->tt, trap_low);

  473.   initialized = 1;
  474. }

  476. asm ("
  477. ! Trap handler for memory errors.  This just sets mem_err to be non-zero.  It
  478. ! assumes that %l1 is non-zero.  This should be safe, as it is doubtful that
  479. ! 0 would ever contain code that could mem fault.  This routine will skip
  480. ! past the faulting instruction after setting mem_err.

  482.         .text
  483.         .align 4

  485. _fltr_set_mem_err:
  486.         sethi %hi(_mem_err), %l0
  487.         st %l1, [%l0 + %lo(_mem_err)]
  488.         jmpl %l2, %g0
  489.         rett %l2+4
  490. ");

  492. static void
  493. ‌set_mem_fault_trap (int enable)
  494. {
  495.   extern void fltr_set_mem_err();
  496.   mem_err = 0;

  498.   if (enable)
  499.     exceptionHandler(9, fltr_set_mem_err);
  500.   else
  501.     exceptionHandler(9, trap_low);
  502. }

  504. /* Convert the SPARC hardware trap type code to a unix signal number. */

  506. static int
  507. ‌computeSignal (int tt)
  508. {
  509.   struct hard_trap_info *ht;

  511.   for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  512.     if (ht->tt == tt)
  513.       return ht->signo;

  515.   return SIGHUP;                /* default for things we don't know about */
  516. }

  518. /*
  519. * While we find nice hex chars, build an int.
  520. * Return number of chars processed.
  521. */

  523. static int
  524. ‌hexToInt(char **ptr, int *intValue)
  525. {
  526.   int numChars = 0;
  527.   int hexValue;

  529.   *intValue = 0;

  531.   while (**ptr)
  532.     {
  533.       hexValue = hex(**ptr);
  534.       if (hexValue < 0)
  535.         break;

  537.       *intValue = (*intValue << 4) | hexValue;
  538.       numChars ++;

  540.       (*ptr)++;
  541.     }

  543.   return (numChars);
  544. }

  546. /*
  547. * This function does all command procesing for interfacing to gdb.  It
  548. * returns 1 if you should skip the instruction at the trap address, 0
  549. * otherwise.
  550. */

  552. extern void breakinst();

  554. static void
  555. ‌handle_exception (unsigned long *registers)
  556. {
  557.   int tt;                        /* Trap type */
  558.   int sigval;
  559.   int addr;
  560.   int length;
  561.   char *ptr;
  562.   unsigned long *sp;

  564. /* First, we must force all of the windows to be spilled out */

  566.   asm("        save %sp, -64, %sp
  567.         save %sp, -64, %sp
  568.         save %sp, -64, %sp
  569.         save %sp, -64, %sp
  570.         save %sp, -64, %sp
  571.         save %sp, -64, %sp
  572.         save %sp, -64, %sp
  573.         save %sp, -64, %sp
  574.         restore
  575.         restore
  576.         restore
  577.         restore
  578.         restore
  579.         restore
  580.         restore
  581.         restore
  582. ");

  584.   if (registers[PC] == (unsigned long)breakinst)
  585.     {
  586.       registers[PC] = registers[NPC];
  587.       registers[NPC] += 4;
  588.     }

  590.   sp = (unsigned long *)registers[SP];

  592.   tt = (registers[TBR] >> 4) & 0xff;

  594.   /* reply to host that an exception has occurred */
  595.   sigval = computeSignal(tt);
  596.   ptr = remcomOutBuffer;

  598.   *ptr++ = 'T';
  599.   *ptr++ = hexchars[sigval >> 4];
  600.   *ptr++ = hexchars[sigval & 0xf];

  602.   *ptr++ = hexchars[PC >> 4];
  603.   *ptr++ = hexchars[PC & 0xf];
  604.   *ptr++ = ':';
  605.   ptr = mem2hex((char *)&registers[PC], ptr, 4, 0);
  606.   *ptr++ = ';';

  608.   *ptr++ = hexchars[FP >> 4];
  609.   *ptr++ = hexchars[FP & 0xf];
  610.   *ptr++ = ':';
  611.   ptr = mem2hex(sp + 8 + 6, ptr, 4, 0); /* FP */
  612.   *ptr++ = ';';

  614.   *ptr++ = hexchars[SP >> 4];
  615.   *ptr++ = hexchars[SP & 0xf];
  616.   *ptr++ = ':';
  617.   ptr = mem2hex((char *)&sp, ptr, 4, 0);
  618.   *ptr++ = ';';

  620.   *ptr++ = hexchars[NPC >> 4];
  621.   *ptr++ = hexchars[NPC & 0xf];
  622.   *ptr++ = ':';
  623.   ptr = mem2hex((char *)&registers[NPC], ptr, 4, 0);
  624.   *ptr++ = ';';

  626.   *ptr++ = hexchars[O7 >> 4];
  627.   *ptr++ = hexchars[O7 & 0xf];
  628.   *ptr++ = ':';
  629.   ptr = mem2hex((char *)&registers[O7], ptr, 4, 0);
  630.   *ptr++ = ';';

  632.   *ptr++ = 0;

  634.   putpacket(remcomOutBuffer);

  636.   while (1)
  637.     {
  638.       remcomOutBuffer[0] = 0;

  640.       ptr = getpacket();
  641.       switch (*ptr++)
  642.         {
  643.         case '?':
  644.           remcomOutBuffer[0] = 'S';
  645.           remcomOutBuffer[1] = hexchars[sigval >> 4];
  646.           remcomOutBuffer[2] = hexchars[sigval & 0xf];
  647.           remcomOutBuffer[3] = 0;
  648.           break;

  650.         case 'd':                /* toggle debug flag */
  651.           break;

  653.         case 'g':                /* return the value of the CPU registers */
  654.           {
  655.             ptr = remcomOutBuffer;
  656.             ptr = mem2hex((char *)registers, ptr, 16 * 4, 0); /* G & O regs */
  657.             ptr = mem2hex(sp + 0, ptr, 16 * 4, 0); /* L & I regs */
  658.             memset(ptr, '0', 32 * 8); /* Floating point */
  659.             mem2hex((char *)&registers[Y],
  660.                     ptr + 32 * 4 * 2,
  661.                     8 * 4,
  662.                     0);                /* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */
  663.           }
  664.           break;

  666.         case 'G':           /* set the value of the CPU registers - return OK */
  667.           {
  668.             unsigned long *newsp, psr;

  670.             psr = registers[PSR];

  672.             hex2mem(ptr, (char *)registers, 16 * 4, 0); /* G & O regs */
  673.             hex2mem(ptr + 16 * 4 * 2, sp + 0, 16 * 4, 0); /* L & I regs */
  674.             hex2mem(ptr + 64 * 4 * 2, (char *)&registers[Y],
  675.                     8 * 4, 0);        /* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */

  677.             /* See if the stack pointer has moved.  If so, then copy the saved
  678.                locals and ins to the new location.  This keeps the window
  679.                overflow and underflow routines happy.  */

  681.             newsp = (unsigned long *)registers[SP];
  682.             if (sp != newsp)
  683.               sp = memcpy(newsp, sp, 16 * 4);

  685.             /* Don't allow CWP to be modified. */

  687.             if (psr != registers[PSR])
  688.               registers[PSR] = (psr & 0x1f) | (registers[PSR] & ~0x1f);

  690.             strcpy(remcomOutBuffer,"OK");
  691.           }
  692.           break;

  694.         case 'm':          /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
  695.           /* Try to read %x,%x.  */

  697.           if (hexToInt(&ptr, &addr)
  698.               && *ptr++ == ','
  699.               && hexToInt(&ptr, &length))
  700.             {
  701.               if (mem2hex((char *)addr, remcomOutBuffer, length, 1))
  702.                 break;

  704.               strcpy (remcomOutBuffer, "E03");
  705.             }
  706.           else
  707.             strcpy(remcomOutBuffer,"E01");
  708.           break;

  710.         case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
  711.           /* Try to read '%x,%x:'.  */

  713.           if (hexToInt(&ptr, &addr)
  714.               && *ptr++ == ','
  715.               && hexToInt(&ptr, &length)
  716.               && *ptr++ == ':')
  717.             {
  718.               if (hex2mem(ptr, (char *)addr, length, 1))
  719.                 strcpy(remcomOutBuffer, "OK");
  720.               else
  721.                 strcpy(remcomOutBuffer, "E03");
  722.             }
  723.           else
  724.             strcpy(remcomOutBuffer, "E02");
  725.           break;

  727.         case 'c':    /* cAA..AA    Continue at address AA..AA(optional) */
  728.           /* try to read optional parameter, pc unchanged if no parm */

  730.           if (hexToInt(&ptr, &addr))
  731.             {
  732.               registers[PC] = addr;
  733.               registers[NPC] = addr + 4;
  734.             }

  736. /* Need to flush the instruction cache here, as we may have deposited a
  737.    breakpoint, and the icache probably has no way of knowing that a data ref to
  738.    some location may have changed something that is in the instruction cache.
  739. */

  741.           flush_i_cache();
  742.           return;

  744.           /* kill the program */
  745.         case 'k' :                /* do nothing */
  746.           break;
  747. #if 0
  748.         case 't':                /* Test feature */
  749.           asm (" std %f30,[%sp]");
  750.           break;
  751. #endif
  752.         case 'r':                /* Reset */
  753.           asm ("call 0
  754.                 nop ");
  755.           break;
  756.         }                        /* switch */

  758.       /* reply to the request */
  759.       putpacket(remcomOutBuffer);
  760.     }
  761. }

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

  768. void
  769. ‌breakpoint (void)
  770. {
  771.   if (!initialized)
  772.     return;

  774.   asm("        .globl _breakinst

  776.         _breakinst: ta 1
  777.       ");
  778. }