Initial creation of sourceware repositorygdb-4_18-branchpoint

1 files changed, 1024 insertions, 0 deletions

diff --git a/gdb/sparcl-stub.c b/gdb/sparcl-stub.c
new file mode 100644
index 0000000..c7994fe
--- /dev/null
+++ b/gdb/sparcl-stub.c
@@ -0,0 +1,1024 @@
+/****************************************************************************
+
+		THIS SOFTWARE IS NOT COPYRIGHTED
+
+   HP offers the following for use in the public domain.  HP makes no
+   warranty with regard to the software or it's performance and the
+   user accepts the software "AS IS" with all faults.
+
+   HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD
+   TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+
+****************************************************************************/
+
+/****************************************************************************
+ *  Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $
+ *
+ *  Module name: remcom.c $
+ *  Revision: 1.34 $
+ *  Date: 91/03/09 12:29:49 $
+ *  Contributor:     Lake Stevens Instrument Division$
+ *
+ *  Description:     low level support for gdb debugger. $
+ *
+ *  Considerations:  only works on target hardware $
+ *
+ *  Written by:      Glenn Engel $
+ *  ModuleState:     Experimental $
+ *
+ *  NOTES:           See Below $
+ *
+ *  Modified for SPARC by Stu Grossman, Cygnus Support.
+ *  Based on sparc-stub.c, it's modified for SPARClite Debug Unit hardware
+ *  breakpoint support to create sparclite-stub.c, by Kung Hsu, Cygnus Support.
+ *
+ *  This code has been extensively tested on the Fujitsu SPARClite demo board.
+ *
+ *  To enable debugger support, two things need to happen.  One, a
+ *  call to set_debug_traps() is necessary in order to allow any breakpoints
+ *  or error conditions to be properly intercepted and reported to gdb.
+ *  Two, a breakpoint needs to be generated to begin communication.  This
+ *  is most easily accomplished by a call to breakpoint().  Breakpoint()
+ *  simulates a breakpoint by executing a trap #1.
+ *
+ *************
+ *
+ *    The following gdb commands are supported:
+ *
+ * command          function                               Return value
+ *
+ *    g             return the value of the CPU registers  hex data or ENN
+ *    G             set the value of the CPU registers     OK or ENN
+ *
+ *    mAA..AA,LLLL  Read LLLL bytes at address AA..AA      hex data or ENN
+ *    MAA..AA,LLLL: Write LLLL bytes at address AA.AA      OK or ENN
+ *
+ *    c             Resume at current address              SNN   ( signal NN)
+ *    cAA..AA       Continue at address AA..AA             SNN
+ *
+ *    s             Step one instruction                   SNN
+ *    sAA..AA       Step one instruction from AA..AA       SNN
+ *
+ *    k             kill
+ *
+ *    ?             What was the last sigval ?             SNN   (signal NN)
+ *
+ *    bBB..BB	    Set baud rate to BB..BB		   OK or BNN, then sets
+ *							   baud rate
+ *
+ * All commands and responses are sent with a packet which includes a
+ * checksum.  A packet consists of
+ *
+ * $<packet info>#<checksum>.
+ *
+ * where
+ * <packet info> :: <characters representing the command or response>
+ * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
+ *
+ * When a packet is received, it is first acknowledged with either '+' or '-'.
+ * '+' indicates a successful transfer.  '-' indicates a failed transfer.
+ *
+ * Example:
+ *
+ * Host:                  Reply:
+ * $m0,10#2a               +$00010203040506070809101112131415#42
+ *
+ ****************************************************************************/
+
+#include <string.h>
+#include <signal.h>
+#include <sparclite.h>
+
+/************************************************************************
+ *
+ * external low-level support routines
+ */
+
+extern void putDebugChar (int c); /* write a single character      */
+extern int getDebugChar (void);	/* read and return a single char */
+
+/************************************************************************/
+/* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/
+/* at least NUMREGBYTES*2 are needed for register packets */
+#define BUFMAX 2048
+
+static int initialized = 0;	/* !0 means we've been initialized */
+
+extern void breakinst ();
+static void set_mem_fault_trap (int enable);
+static void get_in_break_mode (void);
+
+static const char hexchars[]="0123456789abcdef";
+
+#define NUMREGS 80 
+
+/* Number of bytes of registers.  */
+#define NUMREGBYTES (NUMREGS * 4)
+enum regnames {G0, G1, G2, G3, G4, G5, G6, G7,
+		 O0, O1, O2, O3, O4, O5, SP, O7,
+		 L0, L1, L2, L3, L4, L5, L6, L7,
+		 I0, I1, I2, I3, I4, I5, FP, I7,
+
+		 F0, F1, F2, F3, F4, F5, F6, F7,
+		 F8, F9, F10, F11, F12, F13, F14, F15,
+		 F16, F17, F18, F19, F20, F21, F22, F23,
+		 F24, F25, F26, F27, F28, F29, F30, F31,
+		 Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR,
+		 DIA1, DIA2, DDA1, DDA2, DDV1, DDV2, DCR, DSR };
+
+/***************************  ASSEMBLY CODE MACROS *************************/
+/* 									   */
+
+extern void trap_low();
+
+/* Create private copies of common functions used by the stub.  This prevents
+   nasty interactions between app code and the stub (for instance if user steps
+   into strlen, etc..) */
+
+static int
+strlen (const char *s)
+{
+  const char *s1 = s;
+
+  while (*s1++ != '\000');
+
+  return s1 - s;
+}
+
+static char *
+strcpy (char *dst, const char *src)
+{
+  char *retval = dst;
+
+  while ((*dst++ = *src++) != '\000');
+
+  return retval;
+}
+
+static void *
+memcpy (void *vdst, const void *vsrc, int n)
+{
+  char *dst = vdst;
+  const char *src = vsrc;
+  char *retval = dst;
+
+  while (n-- > 0)
+    *dst++ = *src++;
+
+  return retval;
+}
+
+asm("
+	.reserve trapstack, 1000 * 4, \"bss\", 8
+
+	.data
+	.align	4
+
+in_trap_handler:
+	.word	0
+
+	.text
+	.align 4
+
+! This function is called when any SPARC trap (except window overflow or
+! underflow) occurs.  It makes sure that the invalid register window is still
+! available before jumping into C code.  It will also restore the world if you
+! return from handle_exception.
+!
+! On entry, trap_low expects l1 and l2 to contain pc and npc respectivly.
+! Register usage throughout the routine is as follows:
+!
+!	l0 - psr
+!	l1 - pc
+!	l2 - npc
+!	l3 - wim
+!	l4 - scratch and y reg
+!	l5 - scratch and tbr
+!	l6 - unused
+!	l7 - unused
+
+	.globl _trap_low
+_trap_low:
+	mov	%psr, %l0
+	mov	%wim, %l3
+
+	srl	%l3, %l0, %l4		! wim >> cwp
+	cmp	%l4, 1
+	bne	window_fine		! Branch if not in the invalid window
+	nop
+
+! Handle window overflow
+
+	mov	%g1, %l4		! Save g1, we use it to hold the wim
+	srl	%l3, 1, %g1		! Rotate wim right
+	tst	%g1
+	bg	good_wim		! Branch if new wim is non-zero
+	nop
+
+! At this point, we need to bring a 1 into the high order bit of the wim.
+! Since we don't want to make any assumptions about the number of register
+! windows, we figure it out dynamically so as to setup the wim correctly.
+
+	not	%g1			! Fill g1 with ones
+	mov	%g1, %wim		! Fill the wim with ones
+	nop
+	nop
+	nop
+	mov	%wim, %g1		! Read back the wim
+	inc	%g1			! Now g1 has 1 just to left of wim
+	srl	%g1, 1, %g1		! Now put 1 at top of wim
+	mov	%g0, %wim		! Clear wim so that subsequent save
+	nop				!  won't trap
+	nop
+	nop
+
+good_wim:
+	save	%g0, %g0, %g0		! Slip into next window
+	mov	%g1, %wim		! Install the new wim
+
+	std	%l0, [%sp + 0 * 4]	! save L & I registers
+	std	%l2, [%sp + 2 * 4]
+	std	%l4, [%sp + 4 * 4]
+	std	%l6, [%sp + 6 * 4]
+
+	std	%i0, [%sp + 8 * 4]
+	std	%i2, [%sp + 10 * 4]
+	std	%i4, [%sp + 12 * 4]
+	std	%i6, [%sp + 14 * 4]
+
+	restore				! Go back to trap window.
+	mov	%l4, %g1		! Restore %g1
+
+window_fine:
+	sethi	%hi(in_trap_handler), %l4
+	ld	[%lo(in_trap_handler) + %l4], %l5
+	tst	%l5
+	bg	recursive_trap
+	inc	%l5
+
+	set	trapstack+1000*4, %sp	! Switch to trap stack
+
+recursive_trap:
+	st	%l5, [%lo(in_trap_handler) + %l4]
+	sub	%sp,(16+1+6+1+80)*4,%sp	! Make room for input & locals
+ 					! + hidden arg + arg spill
+					! + doubleword alignment
+					! + registers[72] local var
+
+	std	%g0, [%sp + (24 + 0) * 4] ! registers[Gx]
+	std	%g2, [%sp + (24 + 2) * 4]
+	std	%g4, [%sp + (24 + 4) * 4]
+	std	%g6, [%sp + (24 + 6) * 4]
+
+	std	%i0, [%sp + (24 + 8) * 4] ! registers[Ox]
+	std	%i2, [%sp + (24 + 10) * 4]
+	std	%i4, [%sp + (24 + 12) * 4]
+	std	%i6, [%sp + (24 + 14) * 4]
+
+	mov	%y, %l4
+	mov	%tbr, %l5
+	st	%l4, [%sp + (24 + 64) * 4] ! Y
+	st	%l0, [%sp + (24 + 65) * 4] ! PSR
+	st	%l3, [%sp + (24 + 66) * 4] ! WIM
+	st	%l5, [%sp + (24 + 67) * 4] ! TBR
+	st	%l1, [%sp + (24 + 68) * 4] ! PC
+	st	%l2, [%sp + (24 + 69) * 4] ! NPC
+
+	or	%l0, 0xf20, %l4
+	mov	%l4, %psr		! Turn on traps, disable interrupts
+
+	set	0x1000, %l1
+	btst	%l1, %l0		! FP enabled?
+	be	no_fpstore
+	nop
+
+! Must save fsr first, to flush the FQ.  This may cause a deferred fp trap, so
+! traps must be enabled to allow the trap handler to clean things up.
+
+	st	%fsr, [%sp + (24 + 70) * 4]
+
+	std	%f0, [%sp + (24 + 32) * 4]
+	std	%f2, [%sp + (24 + 34) * 4]
+	std	%f4, [%sp + (24 + 36) * 4]
+	std	%f6, [%sp + (24 + 38) * 4]
+	std	%f8, [%sp + (24 + 40) * 4]
+	std	%f10, [%sp + (24 + 42) * 4]
+	std	%f12, [%sp + (24 + 44) * 4]
+	std	%f14, [%sp + (24 + 46) * 4]
+	std	%f16, [%sp + (24 + 48) * 4]
+	std	%f18, [%sp + (24 + 50) * 4]
+	std	%f20, [%sp + (24 + 52) * 4]
+	std	%f22, [%sp + (24 + 54) * 4]
+	std	%f24, [%sp + (24 + 56) * 4]
+	std	%f26, [%sp + (24 + 58) * 4]
+	std	%f28, [%sp + (24 + 60) * 4]
+	std	%f30, [%sp + (24 + 62) * 4]
+no_fpstore:
+
+	call	_handle_exception
+	add	%sp, 24 * 4, %o0	! Pass address of registers
+
+! Reload all of the registers that aren't on the stack
+
+	ld	[%sp + (24 + 1) * 4], %g1 ! registers[Gx]
+	ldd	[%sp + (24 + 2) * 4], %g2
+	ldd	[%sp + (24 + 4) * 4], %g4
+	ldd	[%sp + (24 + 6) * 4], %g6
+
+	ldd	[%sp + (24 + 8) * 4], %i0 ! registers[Ox]
+	ldd	[%sp + (24 + 10) * 4], %i2
+	ldd	[%sp + (24 + 12) * 4], %i4
+	ldd	[%sp + (24 + 14) * 4], %i6
+
+
+	ldd	[%sp + (24 + 64) * 4], %l0 ! Y & PSR
+	ldd	[%sp + (24 + 68) * 4], %l2 ! PC & NPC
+
+	set	0x1000, %l5
+	btst	%l5, %l1		! FP enabled?
+	be	no_fpreload
+	nop
+
+	ldd	[%sp + (24 + 32) * 4], %f0
+	ldd	[%sp + (24 + 34) * 4], %f2
+	ldd	[%sp + (24 + 36) * 4], %f4
+	ldd	[%sp + (24 + 38) * 4], %f6
+	ldd	[%sp + (24 + 40) * 4], %f8
+	ldd	[%sp + (24 + 42) * 4], %f10
+	ldd	[%sp + (24 + 44) * 4], %f12
+	ldd	[%sp + (24 + 46) * 4], %f14
+	ldd	[%sp + (24 + 48) * 4], %f16
+	ldd	[%sp + (24 + 50) * 4], %f18
+	ldd	[%sp + (24 + 52) * 4], %f20
+	ldd	[%sp + (24 + 54) * 4], %f22
+	ldd	[%sp + (24 + 56) * 4], %f24
+	ldd	[%sp + (24 + 58) * 4], %f26
+	ldd	[%sp + (24 + 60) * 4], %f28
+	ldd	[%sp + (24 + 62) * 4], %f30
+
+	ld	[%sp + (24 + 70) * 4], %fsr
+no_fpreload:
+
+	restore				! Ensure that previous window is valid
+	save	%g0, %g0, %g0		!  by causing a window_underflow trap
+
+	mov	%l0, %y
+	mov	%l1, %psr		! Make sure that traps are disabled
+					! for rett
+	sethi	%hi(in_trap_handler), %l4
+	ld	[%lo(in_trap_handler) + %l4], %l5
+	dec	%l5
+	st	%l5, [%lo(in_trap_handler) + %l4]
+
+	jmpl	%l2, %g0		! Restore old PC
+	rett	%l3			! Restore old nPC
+");
+
+/* Convert ch from a hex digit to an int */
+
+static int
+hex(ch)
+     unsigned char ch;
+{
+  if (ch >= 'a' && ch <= 'f')
+    return ch-'a'+10;
+  if (ch >= '0' && ch <= '9')
+    return ch-'0';
+  if (ch >= 'A' && ch <= 'F')
+    return ch-'A'+10;
+  return -1;
+}
+
+/* scan for the sequence $<data>#<checksum>     */
+
+static void
+getpacket(buffer)
+     char *buffer;
+{
+  unsigned char checksum;
+  unsigned char xmitcsum;
+  int i;
+  int count;
+  unsigned char ch;
+
+  do
+    {
+      /* wait around for the start character, ignore all other characters */
+      while ((ch = (getDebugChar() & 0x7f)) != '$') ;
+
+      checksum = 0;
+      xmitcsum = -1;
+
+      count = 0;
+
+      /* now, read until a # or end of buffer is found */
+      while (count < BUFMAX)
+	{
+	  ch = getDebugChar() & 0x7f;
+	  if (ch == '#')
+	    break;
+	  checksum = checksum + ch;
+	  buffer[count] = ch;
+	  count = count + 1;
+	}
+
+      if (count >= BUFMAX)
+	continue;
+
+      buffer[count] = 0;
+
+      if (ch == '#')
+	{
+	  xmitcsum = hex(getDebugChar() & 0x7f) << 4;
+	  xmitcsum |= hex(getDebugChar() & 0x7f);
+#if 0
+	  /* Humans shouldn't have to figure out checksums to type to it. */
+	  putDebugChar ('+');
+	  return;
+#endif
+	  if (checksum != xmitcsum)
+	    putDebugChar('-');	/* failed checksum */
+	  else
+	    {
+	      putDebugChar('+'); /* successful transfer */
+	      /* if a sequence char is present, reply the sequence ID */
+	      if (buffer[2] == ':')
+		{
+		  putDebugChar(buffer[0]);
+		  putDebugChar(buffer[1]);
+		  /* remove sequence chars from buffer */
+		  count = strlen(buffer);
+		  for (i=3; i <= count; i++)
+		    buffer[i-3] = buffer[i];
+		}
+	    }
+	}
+    }
+  while (checksum != xmitcsum);
+}
+
+/* send the packet in buffer.  */
+
+static void
+putpacket(buffer)
+     unsigned char *buffer;
+{
+  unsigned char checksum;
+  int count;
+  unsigned char ch;
+
+  /*  $<packet info>#<checksum>. */
+  do
+    {
+      putDebugChar('$');
+      checksum = 0;
+      count = 0;
+
+      while (ch = buffer[count])
+	{
+	  putDebugChar (ch);
+	  checksum += ch;
+	  count += 1;
+	}
+
+      putDebugChar('#');
+      putDebugChar(hexchars[checksum >> 4]);
+      putDebugChar(hexchars[checksum & 0xf]);
+
+    }
+  while ((getDebugChar() & 0x7f) != '+');
+}
+
+static char remcomInBuffer[BUFMAX];
+static char remcomOutBuffer[BUFMAX];
+
+/* Indicate to caller of mem2hex or hex2mem that there has been an
+   error.  */
+static volatile int mem_err = 0;
+
+/* Convert the memory pointed to by mem into hex, placing result in buf.
+ * Return a pointer to the last char put in buf (null), in case of mem fault,
+ * return 0.
+ * If MAY_FAULT is non-zero, then we will handle memory faults by returning
+ * a 0, else treat a fault like any other fault in the stub.
+ */
+
+static unsigned char *
+mem2hex(mem, buf, count, may_fault)
+     unsigned char *mem;
+     unsigned char *buf;
+     int count;
+     int may_fault;
+{
+  unsigned char ch;
+
+  set_mem_fault_trap(may_fault);
+
+  while (count-- > 0)
+    {
+      ch = *mem++;
+      if (mem_err)
+	return 0;
+      *buf++ = hexchars[ch >> 4];
+      *buf++ = hexchars[ch & 0xf];
+    }
+
+  *buf = 0;
+
+  set_mem_fault_trap(0);
+
+  return buf;
+}
+
+/* convert the hex array pointed to by buf into binary to be placed in mem
+ * return a pointer to the character AFTER the last byte written */
+
+static char *
+hex2mem(buf, mem, count, may_fault)
+     unsigned char *buf;
+     unsigned char *mem;
+     int count;
+     int may_fault;
+{
+  int i;
+  unsigned char ch;
+
+  set_mem_fault_trap(may_fault);
+
+  for (i=0; i<count; i++)
+    {
+      ch = hex(*buf++) << 4;
+      ch |= hex(*buf++);
+      *mem++ = ch;
+      if (mem_err)
+	return 0;
+    }
+
+  set_mem_fault_trap(0);
+
+  return mem;
+}
+
+/* This table contains the mapping between SPARC hardware trap types, and
+   signals, which are primarily what GDB understands.  It also indicates
+   which hardware traps we need to commandeer when initializing the stub. */
+
+static struct hard_trap_info
+{
+  unsigned char tt;		/* Trap type code for SPARClite */
+  unsigned char signo;		/* Signal that we map this trap into */
+} hard_trap_info[] = {
+  {0x01, SIGSEGV},		/* instruction access error */
+  {0x02, SIGILL},		/* privileged instruction */
+  {0x03, SIGILL},		/* illegal instruction */
+  {0x04, SIGEMT},		/* fp disabled */
+  {0x07, SIGBUS},		/* mem address not aligned */
+  {0x09, SIGSEGV},		/* data access exception */
+  {0x0a, SIGEMT},		/* tag overflow */
+  {0x20, SIGBUS},		/* r register access error */
+  {0x21, SIGBUS},		/* instruction access error */
+  {0x24, SIGEMT},		/* cp disabled */
+  {0x29, SIGBUS},		/* data access error */
+  {0x2a, SIGFPE},		/* divide by zero */
+  {0x2b, SIGBUS},		/* data store error */
+  {0x80+1, SIGTRAP},		/* ta 1 - normal breakpoint instruction */
+  {0xff, SIGTRAP},		/* hardware breakpoint */
+  {0, 0}			/* Must be last */
+};
+
+/* Set up exception handlers for tracing and breakpoints */
+
+void
+set_debug_traps()
+{
+  struct hard_trap_info *ht;
+
+/* Only setup fp traps if the FP is disabled.  */
+
+  for (ht = hard_trap_info;
+       ht->tt != 0 && ht->signo != 0;
+       ht++)
+    if (ht->tt != 4 || ! (read_psr () & 0x1000))
+      exceptionHandler(ht->tt, trap_low);
+
+  /* In case GDB is started before us, ack any packets (presumably
+     "$?#xx") sitting there.  */
+
+  putDebugChar ('+');
+
+  initialized = 1;
+}
+
+asm ("
+! Trap handler for memory errors.  This just sets mem_err to be non-zero.  It
+! assumes that %l1 is non-zero.  This should be safe, as it is doubtful that
+! 0 would ever contain code that could mem fault.  This routine will skip
+! past the faulting instruction after setting mem_err.
+
+	.text
+	.align 4
+
+_fltr_set_mem_err:
+	sethi %hi(_mem_err), %l0
+	st %l1, [%l0 + %lo(_mem_err)]
+	jmpl %l2, %g0
+	rett %l2+4
+");
+
+static void
+set_mem_fault_trap(enable)
+     int enable;
+{
+  extern void fltr_set_mem_err();
+  mem_err = 0;
+
+  if (enable)
+    exceptionHandler(9, fltr_set_mem_err);
+  else
+    exceptionHandler(9, trap_low);
+}
+
+asm ("
+	.text
+	.align 4
+
+_dummy_hw_breakpoint:
+	jmpl %l2, %g0
+	rett %l2+4
+	nop
+	nop
+");
+
+static void
+get_in_break_mode()
+{
+  extern void dummy_hw_breakpoint();
+
+  exceptionHandler (255, dummy_hw_breakpoint);
+
+  asm ("ta 255");
+
+  exceptionHandler (255, trap_low);
+}
+
+/* Convert the SPARC hardware trap type code to a unix signal number. */
+
+static int
+computeSignal(tt)
+     int tt;
+{
+  struct hard_trap_info *ht;
+
+  for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
+    if (ht->tt == tt)
+      return ht->signo;
+
+  return SIGHUP;		/* default for things we don't know about */
+}
+
+/*
+ * While we find nice hex chars, build an int.
+ * Return number of chars processed.
+ */
+
+static int
+hexToInt(char **ptr, int *intValue)
+{
+  int numChars = 0;
+  int hexValue;
+
+  *intValue = 0;
+
+  while (**ptr)
+    {
+      hexValue = hex(**ptr);
+      if (hexValue < 0)
+	break;
+
+      *intValue = (*intValue << 4) | hexValue;
+      numChars ++;
+
+      (*ptr)++;
+    }
+
+  return (numChars);
+}
+
+/*
+ * This function does all command procesing for interfacing to gdb.  It
+ * returns 1 if you should skip the instruction at the trap address, 0
+ * otherwise.
+ */
+
+static void
+handle_exception (registers)
+     unsigned long *registers;
+{
+  int tt;			/* Trap type */
+  int sigval;
+  int addr;
+  int length;
+  char *ptr;
+  unsigned long *sp;
+  unsigned long dsr;
+
+/* First, we must force all of the windows to be spilled out */
+
+  asm("	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	save %sp, -64, %sp
+	restore
+	restore
+	restore
+	restore
+	restore
+	restore
+	restore
+	restore
+");
+
+  get_in_break_mode ();		/* Enable DSU register writes */
+
+  registers[DIA1] = read_asi (1, 0xff00);
+  registers[DIA2] = read_asi (1, 0xff04);
+  registers[DDA1] = read_asi (1, 0xff08);
+  registers[DDA2] = read_asi (1, 0xff0c);
+  registers[DDV1] = read_asi (1, 0xff10);
+  registers[DDV2] = read_asi (1, 0xff14);
+  registers[DCR] = read_asi (1, 0xff18);
+  registers[DSR] = read_asi (1, 0xff1c);
+
+  if (registers[PC] == (unsigned long)breakinst)
+    {
+      registers[PC] = registers[NPC];
+      registers[NPC] += 4;
+    }
+  sp = (unsigned long *)registers[SP];
+
+  dsr = (unsigned long)registers[DSR];
+  if (dsr & 0x3c)
+    tt = 255;
+  else
+    tt = (registers[TBR] >> 4) & 0xff;
+
+  /* reply to host that an exception has occurred */
+  sigval = computeSignal(tt);
+  ptr = remcomOutBuffer;
+
+  *ptr++ = 'T';
+  *ptr++ = hexchars[sigval >> 4];
+  *ptr++ = hexchars[sigval & 0xf];
+
+  *ptr++ = hexchars[PC >> 4];
+  *ptr++ = hexchars[PC & 0xf];
+  *ptr++ = ':';
+  ptr = mem2hex((char *)&registers[PC], ptr, 4, 0);
+  *ptr++ = ';';
+
+  *ptr++ = hexchars[FP >> 4];
+  *ptr++ = hexchars[FP & 0xf];
+  *ptr++ = ':';
+  ptr = mem2hex(sp + 8 + 6, ptr, 4, 0); /* FP */
+  *ptr++ = ';';
+
+  *ptr++ = hexchars[SP >> 4];
+  *ptr++ = hexchars[SP & 0xf];
+  *ptr++ = ':';
+  ptr = mem2hex((char *)&sp, ptr, 4, 0);
+  *ptr++ = ';';
+
+  *ptr++ = hexchars[NPC >> 4];
+  *ptr++ = hexchars[NPC & 0xf];
+  *ptr++ = ':';
+  ptr = mem2hex((char *)&registers[NPC], ptr, 4, 0);
+  *ptr++ = ';';
+
+  *ptr++ = hexchars[O7 >> 4];
+  *ptr++ = hexchars[O7 & 0xf];
+  *ptr++ = ':';
+  ptr = mem2hex((char *)&registers[O7], ptr, 4, 0);
+  *ptr++ = ';';
+
+  *ptr++ = 0;
+
+  putpacket(remcomOutBuffer);
+
+  while (1)
+    {
+      remcomOutBuffer[0] = 0;
+
+      getpacket(remcomInBuffer);
+      switch (remcomInBuffer[0])
+	{
+	case '?':
+	  remcomOutBuffer[0] = 'S';
+	  remcomOutBuffer[1] = hexchars[sigval >> 4];
+	  remcomOutBuffer[2] = hexchars[sigval & 0xf];
+	  remcomOutBuffer[3] = 0;
+	  break;
+
+	case 'd':
+				/* toggle debug flag */
+	  break;
+
+	case 'g':		/* return the value of the CPU registers */
+	  memcpy (&registers[L0], sp, 16 * 4); /* Copy L & I regs from stack */
+	  mem2hex ((char *)registers, remcomOutBuffer, NUMREGBYTES, 0);
+	  break;
+
+	case 'G':		/* Set the value of all registers */
+	case 'P':		/* Set the value of one register */
+	  {
+	    unsigned long *newsp, psr;
+
+	    psr = registers[PSR];
+
+	    ptr = &remcomInBuffer[1];
+
+	    if (remcomInBuffer[0] == 'P')
+	      {
+		int regno;
+
+		if (hexToInt (&ptr, &regno)
+		    && *ptr++ == '=')
+		  if (regno >= L0 && regno <= I7)
+		    hex2mem (ptr, sp + regno - L0, 4, 0);
+		  else
+		    hex2mem (ptr, (char *)&registers[regno], 4, 0);
+		else
+		  {
+		    strcpy (remcomOutBuffer, "P01");
+		    break;
+		  }
+	      }
+	    else
+	      {
+		hex2mem (ptr, (char *)registers, NUMREGBYTES, 0);
+		memcpy (sp, &registers[L0], 16 * 4); /* Copy L & I regs to stack */
+	      }
+
+	    /* See if the stack pointer has moved.  If so, then copy the saved
+	       locals and ins to the new location.  This keeps the window
+	       overflow and underflow routines happy.  */
+
+	    newsp = (unsigned long *)registers[SP];
+	    if (sp != newsp)
+	      sp = memcpy(newsp, sp, 16 * 4);
+
+	    /* Don't allow CWP to be modified. */
+
+	    if (psr != registers[PSR])
+	      registers[PSR] = (psr & 0x1f) | (registers[PSR] & ~0x1f);
+
+	    strcpy(remcomOutBuffer,"OK");
+	  }
+	  break;
+
+	case 'm':	  /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
+	  /* Try to read %x,%x.  */
+
+	  ptr = &remcomInBuffer[1];
+
+	  if (hexToInt(&ptr, &addr)
+	      && *ptr++ == ','
+	      && hexToInt(&ptr, &length))
+	    {
+	      if (mem2hex((char *)addr, remcomOutBuffer, length, 1))
+		break;
+
+	      strcpy (remcomOutBuffer, "E03");
+	    }
+	  else
+	    strcpy(remcomOutBuffer,"E01");
+	  break;
+
+	case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
+	  /* Try to read '%x,%x:'.  */
+
+	  ptr = &remcomInBuffer[1];
+
+	  if (hexToInt(&ptr, &addr)
+	      && *ptr++ == ','
+	      && hexToInt(&ptr, &length)
+	      && *ptr++ == ':')
+	    {
+	      if (hex2mem(ptr, (char *)addr, length, 1))
+		strcpy(remcomOutBuffer, "OK");
+	      else
+		strcpy(remcomOutBuffer, "E03");
+	    }
+	  else
+	    strcpy(remcomOutBuffer, "E02");
+	  break;
+
+	case 'c':    /* cAA..AA    Continue at address AA..AA(optional) */
+	  /* try to read optional parameter, pc unchanged if no parm */
+
+	  ptr = &remcomInBuffer[1];
+	  if (hexToInt(&ptr, &addr))
+	    {
+	      registers[PC] = addr;
+	      registers[NPC] = addr + 4;
+	    }
+
+/* Need to flush the instruction cache here, as we may have deposited a
+   breakpoint, and the icache probably has no way of knowing that a data ref to
+   some location may have changed something that is in the instruction cache.
+ */
+
+	  flush_i_cache ();
+
+	  if (!(registers[DSR] & 0x1) /* DSU enabled? */
+	      && !(registers[DCR] & 0x200)) /* Are we in break state? */
+	    {			/* Yes, set the DSU regs */
+	      write_asi (1, 0xff00, registers[DIA1]);
+	      write_asi (1, 0xff04, registers[DIA2]);
+	      write_asi (1, 0xff08, registers[DDA1]);
+	      write_asi (1, 0xff0c, registers[DDA2]);
+	      write_asi (1, 0xff10, registers[DDV1]);
+	      write_asi (1, 0xff14, registers[DDV2]);
+	      write_asi (1, 0xff1c, registers[DSR]);
+	      write_asi (1, 0xff18, registers[DCR] | 0x200); /* Clear break */
+	    }
+
+	  return;
+
+	  /* kill the program */
+	case 'k' :		/* do nothing */
+	  break;
+#if 0
+	case 't':		/* Test feature */
+	  asm (" std %f30,[%sp]");
+	  break;
+#endif
+	case 'r':		/* Reset */
+	  asm ("call 0
+		nop ");
+	  break;
+
+#if 0
+Disabled until we can unscrew this properly
+
+	case 'b':	  /* bBB...  Set baud rate to BB... */
+	  {
+	    int baudrate;
+	    extern void set_timer_3();
+
+	    ptr = &remcomInBuffer[1];
+	    if (!hexToInt(&ptr, &baudrate))
+	      {
+		strcpy(remcomOutBuffer,"B01");
+		break;
+	      }
+
+	    /* Convert baud rate to uart clock divider */
+	    switch (baudrate)
+	      {
+	      case 38400:
+		baudrate = 16;
+		break;
+	      case 19200:
+		baudrate = 33;
+		break;
+	      case 9600:
+		baudrate = 65;
+		break;
+	      default:
+		strcpy(remcomOutBuffer,"B02");
+		goto x1;
+	      }
+
+	    putpacket("OK");	/* Ack before changing speed */
+	    set_timer_3(baudrate); /* Set it */
+	  }
+x1:	  break;
+#endif
+	}			/* switch */
+
+      /* reply to the request */
+      putpacket(remcomOutBuffer);
+    }
+}
+
+/* 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)
+    return;
+
+  asm("	.globl _breakinst
+
+	_breakinst: ta 1
+      ");
+}