summaryrefslogtreecommitdiff
path: root/gnu/usr.bin/binutils/gdb/remote-bug.c
blob: cd3b798c07d3b317525cdc704351d5297f586e37 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
/* Remote debugging interface for Motorola's MVME187BUG monitor, an embedded
   monitor for the m88k.

   Copyright 1992, 1993 Free Software Foundation, Inc.
   Contributed by Cygnus Support.  Written by K. Richard Pixley.

This file is part of GDB.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "inferior.h"
#include "wait.h"

#include "gdb_string.h"
#include <ctype.h>
#include <fcntl.h>
#include <signal.h>
#include <setjmp.h>
#include <errno.h>

#include "terminal.h"
#include "gdbcore.h"
#include "gdbcmd.h"

#include "remote-utils.h"

extern int sleep();

/* External data declarations */
extern int stop_soon_quietly;	/* for wait_for_inferior */

/* Forward data declarations */
extern struct target_ops bug_ops;	/* Forward declaration */

/* Forward function declarations */
static int bug_clear_breakpoints PARAMS((void));

static int bug_read_memory PARAMS((CORE_ADDR memaddr,
					    unsigned char *myaddr,
					    int len));

static int bug_write_memory PARAMS((CORE_ADDR memaddr,
					     unsigned char *myaddr,
					     int len));

/* This variable is somewhat arbitrary.  It's here so that it can be
   set from within a running gdb.  */

static int srec_max_retries = 3;

/* Each S-record download to the target consists of an S0 header
   record, some number of S3 data records, and one S7 termination
   record.  I call this download a "frame".  Srec_frame says how many
   bytes will be represented in each frame.  */

#define SREC_SIZE 160
static int srec_frame = SREC_SIZE;

/* This variable determines how many bytes will be represented in each
   S3 s-record.  */

static int srec_bytes = 40;

/* At one point it appeared to me as though the bug monitor could not
   really be expected to receive two sequential characters at 9600
   baud reliably.  Echo-pacing is an attempt to force data across the
   line even in this condition.  Specifically, in echo-pace mode, each
   character is sent one at a time and we look for the echo before
   sending the next.  This is excruciatingly slow.  */

static int srec_echo_pace = 0;

/* How long to wait after an srec for a possible error message.
   Similar to the above, I tried sleeping after sending each S3 record
   in hopes that I might actually see error messages from the bug
   monitor.  This might actually work if we were to use sleep
   intervals smaller than 1 second.  */

static int srec_sleep = 0;

/* Every srec_noise records, flub the checksum.  This is a debugging
   feature.  Set the variable to something other than 1 in order to
   inject *deliberate* checksum errors.  One might do this if one
   wanted to test error handling and recovery.  */

static int srec_noise = 0;

/* Called when SIGALRM signal sent due to alarm() timeout.  */

/* Number of SIGTRAPs we need to simulate.  That is, the next
   NEED_ARTIFICIAL_TRAP calls to bug_wait should just return
   SIGTRAP without actually waiting for anything.  */

static int need_artificial_trap = 0;

/*
 * Download a file specified in 'args', to the bug.
 */

static void
bug_load (args, fromtty)
     char *args;
     int fromtty;
{
  bfd *abfd;
  asection *s;
  char buffer[1024];

  sr_check_open ();

  dcache_flush (gr_get_dcache());
  inferior_pid = 0;
  abfd = bfd_openr (args, 0);
  if (!abfd)
    {
      printf_filtered ("Unable to open file %s\n", args);
      return;
    }

  if (bfd_check_format (abfd, bfd_object) == 0)
    {
      printf_filtered ("File is not an object file\n");
      return;
    }

  s = abfd->sections;
  while (s != (asection *) NULL)
    {
      srec_frame = SREC_SIZE;
      if (s->flags & SEC_LOAD)
	{
	  int i;

	  char *buffer = xmalloc (srec_frame);

	  printf_filtered ("%s\t: 0x%4x .. 0x%4x  ", s->name, s->vma, s->vma + s->_raw_size);
	  fflush (stdout);
	  for (i = 0; i < s->_raw_size; i += srec_frame)
	    {
	      if (srec_frame > s->_raw_size - i)
		srec_frame = s->_raw_size - i;

	      bfd_get_section_contents (abfd, s, buffer, i, srec_frame);
	      bug_write_memory (s->vma + i, buffer, srec_frame);
	      printf_filtered ("*");
	      fflush (stdout);
	    }
	  printf_filtered ("\n");
	  free (buffer);
	}
      s = s->next;
    }
  sprintf (buffer, "rs ip %lx", (unsigned long) abfd->start_address);
  sr_write_cr (buffer);
  gr_expect_prompt ();
}

#if 0
static char *
get_word (p)
     char **p;
{
  char *s = *p;
  char *word;
  char *copy;
  size_t len;

  while (isspace (*s))
    s++;

  word = s;

  len = 0;

  while (*s && !isspace (*s))
    {
      s++;
      len++;

    }
  copy = xmalloc (len + 1);
  memcpy (copy, word, len);
  copy[len] = 0;
  *p = s;
  return copy;
}
#endif

static struct gr_settings bug_settings = {
  NULL,	/* dcache */
  "Bug>", /* prompt */
  &bug_ops, /* ops */
  bug_clear_breakpoints, /* clear_all_breakpoints */
  bug_read_memory, /* readfunc */
  bug_write_memory, /* writefunc */
  gr_generic_checkin, /* checkin */
};

static char *cpu_check_strings[] = {
  "=",
  "Invalid Register",
};

static void
bug_open (args, from_tty)
     char *args;
     int from_tty;
{
  if (args == NULL)
      args = "";

  gr_open(args, from_tty, &bug_settings);
  /* decide *now* whether we are on an 88100 or an 88110 */
  sr_write_cr("rs cr06");
  sr_expect("rs cr06");

  switch (gr_multi_scan(cpu_check_strings, 0))
    {
    case 0: /* this is an m88100 */
      target_is_m88110 = 0;
      break;
    case 1: /* this is an m88110 */
      target_is_m88110 = 1;
      break;
    default:
      abort();
    }
}

/* Tell the remote machine to resume.  */

void
bug_resume (pid, step, sig)
     int pid, step;
     enum target_signal sig;
{
  dcache_flush (gr_get_dcache());

  if (step)
    {
      sr_write_cr("t");

      /* Force the next bug_wait to return a trap.  Not doing anything
       about I/O from the target means that the user has to type
       "continue" to see any.  FIXME, this should be fixed.  */
      need_artificial_trap = 1;
    }
  else
      sr_write_cr ("g");

  return;
}

/* Wait until the remote machine stops, then return,
   storing status in STATUS just as `wait' would.  */

static char *wait_strings[] = {
  "At Breakpoint",
  "Exception: Data Access Fault (Local Bus Timeout)",
  "\r8???-Bug>",
  "\r197-Bug>",
  NULL,
};

int
bug_wait (pid, status)
     int pid;
     struct target_waitstatus *status;
{
  int old_timeout = sr_get_timeout();
  int old_immediate_quit = immediate_quit;

  status->kind = TARGET_WAITKIND_EXITED;
  status->value.integer = 0;

  /* read off leftovers from resume so that the rest can be passed
     back out as stdout.  */
  if (need_artificial_trap == 0)
    {
      sr_expect("Effective address: ");
      (void) sr_get_hex_word();
      sr_expect ("\r\n");
    }

  sr_set_timeout(-1); /* Don't time out -- user program is running. */
  immediate_quit = 1; /* Helps ability to QUIT */

  switch (gr_multi_scan(wait_strings, need_artificial_trap == 0))
    {
    case 0: /* breakpoint case */
      status->kind = TARGET_WAITKIND_STOPPED;
      status->value.sig = TARGET_SIGNAL_TRAP;
      /* user output from the target can be discarded here. (?) */
      gr_expect_prompt();
      break;

    case 1: /* bus error */
      status->kind = TARGET_WAITKIND_STOPPED;
      status->value.sig = TARGET_SIGNAL_BUS;
      /* user output from the target can be discarded here. (?) */
      gr_expect_prompt();
      break;

    case 2: /* normal case */
    case 3:
      if (need_artificial_trap != 0)
	{
	  /* stepping */
	  status->kind = TARGET_WAITKIND_STOPPED;
	  status->value.sig = TARGET_SIGNAL_TRAP;
	  need_artificial_trap--;
	  break;
	}
      else
	{
	  /* exit case */
	  status->kind = TARGET_WAITKIND_EXITED;
	  status->value.integer = 0;
	  break;
	}

    case -1: /* trouble */
    default:
      fprintf_filtered (stderr,
			"Trouble reading target during wait\n");
      break;
    }

  sr_set_timeout(old_timeout);
  immediate_quit = old_immediate_quit;
  return 0;
}

/* Return the name of register number REGNO
   in the form input and output by bug.

   Returns a pointer to a static buffer containing the answer.  */
static char *
get_reg_name (regno)
     int regno;
{
  static char *rn[] = {
    "r00", "r01", "r02", "r03", "r04", "r05", "r06", "r07",
    "r08", "r09", "r10", "r11", "r12", "r13", "r14", "r15",
    "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
    "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",

    /* these get confusing because we omit a few and switch some ordering around. */

    "cr01",  /* 32 = psr */
    "fcr62", /* 33 = fpsr*/
    "fcr63", /* 34 = fpcr */
    "ip",			/* this is something of a cheat. */
  /* 35 = sxip */
    "cr05", /* 36 = snip */
    "cr06", /* 37 = sfip */

    "x00", "x01", "x02", "x03", "x04", "x05", "x06", "x07",
    "x08", "x09", "x10", "x11", "x12", "x13", "x14", "x15",
    "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
    "x24", "x25", "x26", "x27", "x28", "x29", "x30", "x31",
  };

  return rn[regno];
}

#if 0 /* not currently used */
/* Read from remote while the input matches STRING.  Return zero on
   success, -1 on failure.  */

static int
bug_scan (s)
     char *s;
{
  int c;

  while (*s)
    {
      c = sr_readchar();
      if (c != *s++)
	{
	  fflush(stdout);
	  printf("\nNext character is '%c' - %d and s is \"%s\".\n", c, c, --s);
	  return(-1);
	}
    }

  return(0);
}
#endif /* never */

static int
bug_srec_write_cr (s)
     char *s;
{
  char *p = s;

  if (srec_echo_pace)
    for (p = s; *p; ++p)
      {
	if (sr_get_debug() > 0)
	  printf ("%c", *p);

	do
	  SERIAL_WRITE(sr_get_desc(), p, 1);
	while (sr_pollchar() != *p);
      }
  else
    {  
      sr_write_cr (s);
/*       return(bug_scan (s) || bug_scan ("\n")); */
    }

  return(0);
}

/* Store register REGNO, or all if REGNO == -1. */

static void
bug_fetch_register(regno)
     int regno;
{
  sr_check_open();

  if (regno == -1)
    {
      int i;

      for (i = 0; i < NUM_REGS; ++i)
	bug_fetch_register(i);
    }
  else if (target_is_m88110 && regno == SFIP_REGNUM)
    {
      /* m88110 has no sfip. */
      long l = 0;
      supply_register(regno, (char *) &l);
    }
  else if (regno < XFP_REGNUM)
    {
      char buffer[MAX_REGISTER_RAW_SIZE];

      sr_write ("rs ", 3);
      sr_write_cr (get_reg_name(regno));
      sr_expect ("=");
      store_unsigned_integer (buffer, REGISTER_RAW_SIZE (regno),
			      sr_get_hex_word());
      gr_expect_prompt ();
      supply_register (regno, buffer);
    }
  else
    {
      /* Float register so we need to parse a strange data format. */
      long p;
      unsigned char fpreg_buf[10];

      sr_write("rs ", 3);
      sr_write(get_reg_name(regno), strlen(get_reg_name(regno)));
      sr_write_cr(";d");
      sr_expect("rs");
      sr_expect(get_reg_name(regno));
      sr_expect(";d");
      sr_expect("=");

      /* sign */
      p = sr_get_hex_digit(1);
      fpreg_buf[0] = p << 7;

      /* exponent */
      sr_expect("_");
      p = sr_get_hex_digit(1);
      fpreg_buf[0] += (p << 4);
      fpreg_buf[0] += sr_get_hex_digit(1);

      fpreg_buf[1] = sr_get_hex_digit(1) << 4;

      /* fraction */
      sr_expect("_");
      fpreg_buf[1] += sr_get_hex_digit(1);

      fpreg_buf[2] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[3] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[4] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[5] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[6] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[7] = (sr_get_hex_digit(1) << 4) + sr_get_hex_digit(1);
      fpreg_buf[8] = 0;
      fpreg_buf[9] = 0;

      gr_expect_prompt();
      supply_register(regno, fpreg_buf);
    }

  return;
}

/* Store register REGNO, or all if REGNO == -1. */

static void
bug_store_register (regno)
     int regno;
{
  char buffer[1024];
  sr_check_open();

  if (regno == -1)
    {
      int i;

      for (i = 0; i < NUM_REGS; ++i)
	bug_store_register(i);
    }
  else
    {
      char *regname;

      regname = get_reg_name(regno);

      if (target_is_m88110 && regno == SFIP_REGNUM)
	return;
      else if (regno < XFP_REGNUM)
	sprintf(buffer, "rs %s %08x",
		regname,
		read_register(regno));
      else
	{
	  unsigned char *fpreg_buf =
	    (unsigned char *)&registers[REGISTER_BYTE(regno)];
	  
	  sprintf(buffer, "rs %s %1x_%02x%1x_%1x%02x%02x%02x%02x%02x%02x;d",
		  regname,
		  /* sign */
		  (fpreg_buf[0] >> 7) & 0xf,
		  /* exponent */
		  fpreg_buf[0] & 0x7f,
		  (fpreg_buf[1] >> 8) & 0xf,
		  /* fraction */
		  fpreg_buf[1] & 0xf,
		  fpreg_buf[2],
		  fpreg_buf[3],
		  fpreg_buf[4],
		  fpreg_buf[5],
		  fpreg_buf[6],
		  fpreg_buf[7]);
	}

      sr_write_cr(buffer);
      gr_expect_prompt();
    }

  return;
}

int
bug_xfer_memory (memaddr, myaddr, len, write, target)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
     int write;
     struct target_ops *target;	/* ignored */
{
  register int i;

  /* Round starting address down to longword boundary.  */
  register CORE_ADDR addr;

  /* Round ending address up; get number of longwords that makes.  */
  register int count;

  /* Allocate buffer of that many longwords.  */
  register int *buffer;

  addr = memaddr & -sizeof (int);
  count = (((memaddr + len) - addr) + sizeof (int) - 1) / sizeof (int);

  buffer = (int *) alloca (count * sizeof (int));

  if (write)
    {
      /* Fill start and end extra bytes of buffer with existing memory data.  */

      if (addr != memaddr || len < (int) sizeof (int))
	{
	  /* Need part of initial word -- fetch it.  */
	  buffer[0] = gr_fetch_word (addr);
	}

      if (count > 1)		/* FIXME, avoid if even boundary */
	{
	  buffer[count - 1]
	    = gr_fetch_word (addr + (count - 1) * sizeof (int));
	}

      /* Copy data to be written over corresponding part of buffer */

      memcpy ((char *) buffer + (memaddr & (sizeof (int) - 1)), myaddr, len);

      /* Write the entire buffer.  */

      for (i = 0; i < count; i++, addr += sizeof (int))
	{
	  errno = 0;
	  gr_store_word (addr, buffer[i]);
	  if (errno)
	    {

	      return 0;
	    }

	}
    }
  else
    {
      /* Read all the longwords */
      for (i = 0; i < count; i++, addr += sizeof (int))
	{
	  errno = 0;
	  buffer[i] = gr_fetch_word (addr);
	  if (errno)
	    {
	      return 0;
	    }
	  QUIT;
	}

      /* Copy appropriate bytes out of the buffer.  */
      memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (int) - 1)), len);
    }

  return len;
}

static void
start_load()
{
  char *command;

  command = (srec_echo_pace ? "lo 0 ;x" : "lo 0");

  sr_write_cr (command);
  sr_expect (command);
  sr_expect ("\r\n");
  bug_srec_write_cr ("S0030000FC");
  return;
}

/* This is an extremely vulnerable and fragile function.  I've made
   considerable attempts to make this deterministic, but I've
   certainly forgotten something.  The trouble is that S-records are
   only a partial file format, not a protocol.  Worse, apparently the
   m88k bug monitor does not run in real time while receiving
   S-records.  Hence, we must pay excruciating attention to when and
   where error messages are returned, and what has actually been sent.

   Each call represents a chunk of memory to be sent to the target.
   We break that chunk into an S0 header record, some number of S3
   data records each containing srec_bytes, and an S7 termination
   record.  */

static char *srecord_strings[] = {
  "S-RECORD",
  "-Bug>",
  NULL,
};

static int
bug_write_memory (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     unsigned char *myaddr;
     int len;
{
  int done;
  int checksum;
  int x;
  int retries;
  char *buffer = alloca ((srec_bytes + 8) << 1);

  retries = 0;

  do
    {
      done = 0;

      if (retries > srec_max_retries)
	return(-1);

      if (retries > 0)
	{
	  if (sr_get_debug() > 0)
	    printf("\n<retrying...>\n");

	  /* This gr_expect_prompt call is extremely important.  Without
	     it, we will tend to resend our packet so fast that it
	     will arrive before the bug monitor is ready to receive
	     it.  This would lead to a very ugly resend loop.  */

	  gr_expect_prompt();
	}

      start_load();

      while (done < len)
	{
	  int thisgo;
	  int idx;
	  char *buf = buffer;
	  CORE_ADDR address;

	  checksum = 0;
	  thisgo = len - done;
	  if (thisgo > srec_bytes)
	    thisgo = srec_bytes;

	  address = memaddr + done;
	  sprintf (buf, "S3%02X%08X", thisgo + 4 + 1, address);
	  buf += 12;

	  checksum += (thisgo + 4 + 1
		       + (address & 0xff)
		       + ((address >>  8) & 0xff)
		       + ((address >> 16) & 0xff)
		       + ((address >> 24) & 0xff));

	  for (idx = 0; idx < thisgo; idx++)
	    {
	      sprintf (buf, "%02X", myaddr[idx + done]);
	      checksum += myaddr[idx + done];
	      buf += 2;
	    }

	  if (srec_noise > 0)
	    {
	      /* FIXME-NOW: insert a deliberate error every now and then.
		 This is intended for testing/debugging the error handling
		 stuff.  */
	      static int counter = 0;
	      if (++counter > srec_noise)
		{
		  counter = 0;
		  ++checksum;
		}
	    }

	  sprintf(buf, "%02X", ~checksum & 0xff);
	  bug_srec_write_cr (buffer);

	  if (srec_sleep != 0)
	    sleep(srec_sleep);

	  /* This pollchar is probably redundant to the gr_multi_scan
	     below.  Trouble is, we can't be sure when or where an
	     error message will appear.  Apparently, when running at
	     full speed from a typical sun4, error messages tend to
	     appear to arrive only *after* the s7 record.   */

	  if ((x = sr_pollchar()) != 0)
	    {
	      if (sr_get_debug() > 0)
		printf("\n<retrying...>\n");

	      ++retries;

	      /* flush any remaining input and verify that we are back
		 at the prompt level. */
	      gr_expect_prompt();
	      /* start all over again. */
	      start_load();
	      done = 0;
	      continue;
	    }

	  done += thisgo;
	}

      bug_srec_write_cr("S7060000000000F9");
      ++retries;

      /* Having finished the load, we need to figure out whether we
	 had any errors.  */
    } while (gr_multi_scan(srecord_strings, 0) == 0);;

  return(0);
}

/* Copy LEN bytes of data from debugger memory at MYADDR
   to inferior's memory at MEMADDR.  Returns errno value.
 * sb/sh instructions don't work on unaligned addresses, when TU=1.
 */

/* Read LEN bytes from inferior memory at MEMADDR.  Put the result
   at debugger address MYADDR.  Returns errno value.  */
static int
bug_read_memory (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     unsigned char *myaddr;
     int len;
{
  char request[100];
  char *buffer;
  char *p;
  char type;
  char size;
  unsigned char c;
  unsigned int inaddr;
  unsigned int checksum;

  sprintf(request, "du 0 %x:&%d", memaddr, len);
  sr_write_cr(request);

  p = buffer = alloca(len);

  /* scan up through the header */
  sr_expect("S0030000FC");

  while (p < buffer + len)
    {
      /* scan off any white space. */
      while (sr_readchar() != 'S') ;;

      /* what kind of s-rec? */
      type = sr_readchar();

      /* scan record size */
      sr_get_hex_byte(&size);
      checksum = size;
      --size;
      inaddr = 0;

      switch (type)
	{
	case '7':
	case '8':
	case '9':
	  goto done;

	case '3':
	  sr_get_hex_byte(&c);
	  inaddr = (inaddr << 8) + c;
	  checksum += c;
	  --size;
	  /* intentional fall through */
	case '2':
	  sr_get_hex_byte(&c);
	  inaddr = (inaddr << 8) + c;
	  checksum += c;
	  --size;
	  /* intentional fall through */
	case '1':
	  sr_get_hex_byte(&c);
	  inaddr = (inaddr << 8) + c;
	  checksum += c;
	  --size;
	  sr_get_hex_byte(&c);
	  inaddr = (inaddr << 8) + c;
	  checksum += c;
	  --size;
	  break;

	default:
	  /* bonk */
	  error("reading s-records.");
	}

      if (inaddr < memaddr
	  || (memaddr + len) < (inaddr + size))
	error("srec out of memory range.");

      if (p != buffer + inaddr - memaddr)
	error("srec out of sequence.");

      for (; size; --size, ++p)
	{
	  sr_get_hex_byte(p);
	  checksum += *p;
	}

      sr_get_hex_byte(&c);
      if (c != (~checksum & 0xff))
	error("bad s-rec checksum");
    }

 done:
  gr_expect_prompt();
  if (p != buffer + len)
    return(1);

  memcpy(myaddr, buffer, len);
  return(0);
}

#define MAX_BREAKS	16
static int num_brkpts = 0;
static int
bug_insert_breakpoint (addr, save)
     CORE_ADDR addr;
     char *save;		/* Throw away, let bug save instructions */
{
  sr_check_open ();

  if (num_brkpts < MAX_BREAKS)
    {
      char buffer[100];

      num_brkpts++;
      sprintf (buffer, "br %x", addr);
      sr_write_cr (buffer);
      gr_expect_prompt ();
      return(0);
    }
  else
    {
      fprintf_filtered (stderr,
		      "Too many break points, break point not installed\n");
      return(1);
    }

}
static int
bug_remove_breakpoint (addr, save)
     CORE_ADDR addr;
     char *save;		/* Throw away, let bug save instructions */
{
  if (num_brkpts > 0)
    {
      char buffer[100];

      num_brkpts--;
      sprintf (buffer, "nobr %x", addr);
      sr_write_cr (buffer);
      gr_expect_prompt ();

    }
  return (0);
}

/* Clear the bugs notion of what the break points are */
static int
bug_clear_breakpoints ()
{

  if (sr_is_open())
    {
      sr_write_cr ("nobr");
      sr_expect("nobr");
      gr_expect_prompt ();
    }
  num_brkpts = 0;
  return(0);
}

struct target_ops bug_ops =
{
  "bug", "Remote BUG monitor",
  "Use the mvme187 board running the BUG monitor connected by a serial line.",

  bug_open, gr_close,
  0, gr_detach, bug_resume, bug_wait,	/* attach */
  bug_fetch_register, bug_store_register,
  gr_prepare_to_store,
  bug_xfer_memory,
  gr_files_info,
  bug_insert_breakpoint, bug_remove_breakpoint,	/* Breakpoints */
  0, 0, 0, 0, 0,		/* Terminal handling */
  gr_kill,			/* FIXME, kill */
  bug_load,
  0,				/* lookup_symbol */
  gr_create_inferior,		/* create_inferior */
  gr_mourn,			/* mourn_inferior FIXME */
  0,				/* can_run */
  0,				/* notice_signals */
  process_stratum, 0,		/* next */
  1, 1, 1, 1, 1,		/* all mem, mem, stack, regs, exec */
  0, 0,				/* Section pointers */
  OPS_MAGIC,			/* Always the last thing */
};

void
_initialize_remote_bug ()
{
  add_target (&bug_ops);

  add_show_from_set
    (add_set_cmd ("srec-bytes", class_support, var_uinteger,
		  (char *) &srec_bytes,
		  "\
Set the number of bytes represented in each S-record.\n\
This affects the communication protocol with the remote target.",
		  &setlist),
     &showlist);

  add_show_from_set
    (add_set_cmd ("srec-max-retries", class_support, var_uinteger,
		  (char *) &srec_max_retries,
		  "\
Set the number of retries for shipping S-records.\n\
This affects the communication protocol with the remote target.",
		  &setlist),
     &showlist);

#if 0
  /* This needs to set SREC_SIZE, not srec_frame which gets changed at the
     end of a download.  But do we need the option at all?  */
  add_show_from_set
    (add_set_cmd ("srec-frame", class_support, var_uinteger,
		  (char *) &srec_frame,
		  "\
Set the number of bytes in an S-record frame.\n\
This affects the communication protocol with the remote target.",
		  &setlist),
     &showlist);
#endif /* 0 */

  add_show_from_set
    (add_set_cmd ("srec-noise", class_support, var_zinteger,
		  (char *) &srec_noise,
		  "\
Set number of S-record to send before deliberately flubbing a checksum.\n\
Zero means flub none at all.  This affects the communication protocol\n\
with the remote target.",
		  &setlist),
     &showlist);

  add_show_from_set
    (add_set_cmd ("srec-sleep", class_support, var_zinteger,
		  (char *) &srec_sleep,
		  "\
Set number of seconds to sleep after an S-record for a possible error message to arrive.\n\
This affects the communication protocol with the remote target.",
		  &setlist),
     &showlist);

  add_show_from_set
    (add_set_cmd ("srec-echo-pace", class_support, var_boolean,
		  (char *) &srec_echo_pace,
		  "\
Set echo-verification.\n\
When on, use verification by echo when downloading S-records.  This is\n\
much slower, but generally more reliable.", 
		  &setlist),
     &showlist);
}