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simh-testsetgenerator/sim_tape.c
Bob Supnik 9c4779c061 Notes For V3.8 
The makefile now works for Linux and most Unix's. Howevr, for Solaris
and MacOS, you must first export the OSTYPE environment variable:

> export OSTYPE
> make

Otherwise, you will get build errors.

1. New Features

1.1 3.8-0

1.1.1 SCP and Libraries

- BREAK, NOBREAK, and SHOW BREAK with no argument will set, clear, and
  show (respectively) a breakpoint at the current PC.

1.1.2 GRI

- Added support for the GRI-99 processor.

1.1.3 HP2100

- Added support for the BACI terminal interface.
- Added support for RTE OS/VMA/EMA, SIGNAL, VIS firmware extensions.

1.1.4 Nova

- Added support for 64KW memory (implemented in third-party CPU's).

1.1.5 PDP-11

- Added support for DC11, RC11, KE11A, KG11A.
- Added modem control support for DL11.
- Added ASCII character support for all 8b devices.

1.2 3.8-1

1.2.1 SCP and libraries

- Added capability to set line connection order for terminal multiplexers.

1.2.2 HP2100

- Added support for 12620A/12936A privileged interrupt fence.
- Added support for 12792C eight-channel asynchronous multiplexer.

2. Bugs Fixed

Please see the revision history on http://simh.trailing-edge.com or
in the source module sim_rev.h.
2011-04-15 08:35:54 -07:00

984 lines
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/* sim_tape.c: simulator tape support library
Copyright (c) 1993-2008, Robert M Supnik
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of Robert M Supnik shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from Robert M Supnik.
Ultimately, this will be a place to hide processing of various tape formats,
as well as OS-specific direct hardware access.
08-Jun-08 JDB Fixed signed/unsigned warning in sim_tape_set_fmt
23-Jan-07 JDB Fixed backspace over gap at BOT
22-Jan-07 RMS Fixed bug in P7B format read reclnt rev (found by Rich Cornwell)
15-Dec-06 RMS Added support for small capacity tapes
30-Aug-06 JDB Added erase gap support
14-Feb-06 RMS Added variable tape capacity
23-Jan-06 JDB Fixed odd-byte-write problem in sim_tape_wrrecf
17-Dec-05 RMS Added write support for Paul Pierce 7b format
16-Aug-05 RMS Fixed C++ declaration and cast problems
02-May-05 RMS Added support for Pierce 7b format
28-Jul-04 RMS Fixed bug in writing error records (found by Dave Bryan)
RMS Fixed incorrect error codes (found by Dave Bryan)
05-Jan-04 RMS Revised for file I/O library
25-Apr-03 RMS Added extended file support
28-Mar-03 RMS Added E11 and TPC format support
Public routines:
sim_tape_attach attach tape unit
sim_tape_detach detach tape unit
sim_tape_rdrecf read tape record forward
sim_tape_rdrecr read tape record reverse
sim_tape_wrrecf write tape record forward
sim_tape_sprecf space tape record forward
sim_tape_sprecr space tape record reverse
sim_tape_wrtmk write tape mark
sim_tape_wreom erase remainder of tape
sim_tape_wrgap write erase gap
sim_tape_rewind rewind
sim_tape_reset reset unit
sim_tape_bot TRUE if at beginning of tape
sim_tape_eot TRUE if at or beyond end of tape
sim_tape_wrp TRUE if write protected
sim_tape_set_fmt set tape format
sim_tape_show_fmt show tape format
sim_tape_set_capac set tape capacity
sim_tape_show_capac show tape capacity
*/
#include "sim_defs.h"
#include "sim_tape.h"
struct sim_tape_fmt {
char *name; /* name */
int32 uflags; /* unit flags */
t_addr bot; /* bot test */
};
static struct sim_tape_fmt fmts[MTUF_N_FMT] = {
{ "SIMH", 0, sizeof (t_mtrlnt) - 1 },
{ "E11", 0, sizeof (t_mtrlnt) - 1 },
{ "TPC", UNIT_RO, sizeof (t_tpclnt) - 1 },
{ "P7B", 0, 0 },
/* { "TPF", UNIT_RO, 0 }, */
{ NULL, 0, 0 }
};
extern int32 sim_switches;
t_stat sim_tape_ioerr (UNIT *uptr);
t_stat sim_tape_wrdata (UNIT *uptr, uint32 dat);
uint32 sim_tape_tpc_map (UNIT *uptr, t_addr *map);
t_addr sim_tape_tpc_fnd (UNIT *uptr, t_addr *map);
/* Attach tape unit */
t_stat sim_tape_attach (UNIT *uptr, char *cptr)
{
uint32 objc;
char gbuf[CBUFSIZE];
t_stat r;
if (sim_switches & SWMASK ('F')) { /* format spec? */
cptr = get_glyph (cptr, gbuf, 0); /* get spec */
if (*cptr == 0) /* must be more */
return SCPE_2FARG;
if (sim_tape_set_fmt (uptr, 0, gbuf, NULL) != SCPE_OK)
return SCPE_ARG;
}
r = attach_unit (uptr, cptr); /* attach unit */
if (r != SCPE_OK) /* error? */
return r;
switch (MT_GET_FMT (uptr)) { /* case on format */
case MTUF_F_TPC: /* TPC */
objc = sim_tape_tpc_map (uptr, NULL); /* get # objects */
if (objc == 0) { /* tape empty? */
sim_tape_detach (uptr);
return SCPE_FMT; /* yes, complain */
}
uptr->filebuf = calloc (objc + 1, sizeof (t_addr));
if (uptr->filebuf == NULL) { /* map allocated? */
sim_tape_detach (uptr);
return SCPE_MEM; /* no, complain */
}
uptr->hwmark = objc + 1; /* save map size */
sim_tape_tpc_map (uptr, (t_addr *) uptr->filebuf); /* fill map */
break;
default:
break;
}
sim_tape_rewind (uptr);
return SCPE_OK;
}
/* Detach tape unit */
t_stat sim_tape_detach (UNIT *uptr)
{
uint32 f = MT_GET_FMT (uptr);
t_stat r;
r = detach_unit (uptr); /* detach unit */
if (r != SCPE_OK)
return r;
switch (f) { /* case on format */
case MTUF_F_TPC: /* TPC */
if (uptr->filebuf) /* free map */
free (uptr->filebuf);
uptr->filebuf = NULL;
uptr->hwmark = 0;
break;
default:
break;
}
sim_tape_rewind (uptr);
return SCPE_OK;
}
/* Read record length forward (internal routine)
Inputs:
uptr = pointer to tape unit
bc = pointer to returned record length
Outputs:
status = operation status
exit condition position
unit unattached unchanged
read error unchanged, PNU set
end of file/medium unchanged, PNU set
tape mark updated
data record updated, sim_fread will read record forward
See notes at "sim_tape_wrgap" regarding erase gap implementation.
*/
t_stat sim_tape_rdlntf (UNIT *uptr, t_mtrlnt *bc)
{
uint8 c;
t_bool all_eof;
uint32 f = MT_GET_FMT (uptr);
t_mtrlnt sbc;
t_tpclnt tpcbc;
MT_CLR_PNU (uptr);
if ((uptr->flags & UNIT_ATT) == 0) /* not attached? */
return MTSE_UNATT;
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* set tape pos */
switch (f) { /* switch on fmt */
case MTUF_F_STD: case MTUF_F_E11:
do {
sim_fread (bc, sizeof (t_mtrlnt), 1, uptr->fileref); /* read rec lnt */
sbc = MTR_L (*bc); /* save rec lnt */
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr); /* pos not upd */
return sim_tape_ioerr (uptr);
}
if (feof (uptr->fileref) || (*bc == MTR_EOM)) { /* eof or eom? */
MT_SET_PNU (uptr); /* pos not upd */
return MTSE_EOM;
}
uptr->pos = uptr->pos + sizeof (t_mtrlnt); /* spc over rec lnt */
if (*bc == MTR_TMK) /* tape mark? */
return MTSE_TMK;
if (*bc == MTR_FHGAP) { /* half gap? */
uptr->pos = uptr->pos + sizeof (t_mtrlnt) / 2; /* half space fwd */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* resync */
}
else if (*bc != MTR_GAP)
uptr->pos = uptr->pos + sizeof (t_mtrlnt) + /* spc over record */
((f == MTUF_F_STD)? ((sbc + 1) & ~1): sbc);
}
while ((*bc == MTR_GAP) || (*bc == MTR_FHGAP));
break;
case MTUF_F_TPC:
sim_fread (&tpcbc, sizeof (t_tpclnt), 1, uptr->fileref);
*bc = tpcbc; /* save rec lnt */
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr); /* pos not upd */
return sim_tape_ioerr (uptr);
}
if (feof (uptr->fileref)) { /* eof? */
MT_SET_PNU (uptr); /* pos not upd */
return MTSE_EOM;
}
uptr->pos = uptr->pos + sizeof (t_tpclnt); /* spc over reclnt */
if (tpcbc == TPC_TMK) /* tape mark? */
return MTSE_TMK;
uptr->pos = uptr->pos + ((tpcbc + 1) & ~1); /* spc over record */
break;
case MTUF_F_P7B:
for (sbc = 0, all_eof = 1; ; sbc++) { /* loop thru record */
sim_fread (&c, sizeof (uint8), 1, uptr->fileref);
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr); /* pos not upd */
return sim_tape_ioerr (uptr);
}
if (feof (uptr->fileref)) { /* eof? */
if (sbc == 0) /* no data? eom */
return MTSE_EOM;
break; /* treat like eor */
}
if ((sbc != 0) && (c & P7B_SOR)) /* next record? */
break;
if ((c & P7B_DPAR) != P7B_EOF)
all_eof = 0;
}
*bc = sbc; /* save rec lnt */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* for read */
uptr->pos = uptr->pos + sbc; /* spc over record */
if (all_eof) /* tape mark? */
return MTSE_TMK;
break;
default:
return MTSE_FMT;
}
return MTSE_OK;
}
/* Read record length reverse (internal routine)
Inputs:
uptr = pointer to tape unit
bc = pointer to returned record length
Outputs:
status = operation status
exit condition position
unit unattached unchanged
beginning of tape unchanged
read error unchanged
end of file unchanged
end of medium updated
tape mark updated
data record updated, sim_fread will read record forward
See notes at "sim_tape_wrgap" regarding erase gap implementation.
*/
t_stat sim_tape_rdlntr (UNIT *uptr, t_mtrlnt *bc)
{
uint8 c;
t_bool all_eof;
uint32 f = MT_GET_FMT (uptr);
t_addr ppos;
t_mtrlnt sbc;
t_tpclnt tpcbc;
MT_CLR_PNU (uptr);
if ((uptr->flags & UNIT_ATT) == 0) /* not attached? */
return MTSE_UNATT;
if (sim_tape_bot (uptr)) /* at BOT? */
return MTSE_BOT;
switch (f) { /* switch on fmt */
case MTUF_F_STD: case MTUF_F_E11:
do {
sim_fseek (uptr->fileref, uptr->pos - sizeof (t_mtrlnt), SEEK_SET);
sim_fread (bc, sizeof (t_mtrlnt), 1, uptr->fileref); /* read rec lnt */
sbc = MTR_L (*bc);
if (ferror (uptr->fileref)) /* error? */
return sim_tape_ioerr (uptr);
if (feof (uptr->fileref)) /* eof? */
return MTSE_EOM;
uptr->pos = uptr->pos - sizeof (t_mtrlnt); /* spc over rec lnt */
if (*bc == MTR_EOM) /* eom? */
return MTSE_EOM;
if (*bc == MTR_TMK) /* tape mark? */
return MTSE_TMK;
if ((*bc & MTR_M_RHGAP) == MTR_RHGAP) { /* half gap? */
uptr->pos = uptr->pos + sizeof (t_mtrlnt) / 2; /* half space rev */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* resync */
}
else if (*bc != MTR_GAP) {
uptr->pos = uptr->pos - sizeof (t_mtrlnt) - /* spc over record */
((f == MTUF_F_STD)? ((sbc + 1) & ~1): sbc);
sim_fseek (uptr->fileref, uptr->pos + sizeof (t_mtrlnt), SEEK_SET);
}
else if (sim_tape_bot (uptr)) /* backed into BOT? */
return MTSE_BOT;
}
while ((*bc == MTR_GAP) || (*bc == MTR_RHGAP));
break;
case MTUF_F_TPC:
ppos = sim_tape_tpc_fnd (uptr, (t_addr *) uptr->filebuf); /* find prev rec */
sim_fseek (uptr->fileref, ppos, SEEK_SET); /* position */
sim_fread (&tpcbc, sizeof (t_tpclnt), 1, uptr->fileref);
*bc = tpcbc; /* save rec lnt */
if (ferror (uptr->fileref)) /* error? */
return sim_tape_ioerr (uptr);
if (feof (uptr->fileref)) /* eof? */
return MTSE_EOM;
uptr->pos = ppos; /* spc over record */
if (*bc == MTR_TMK) /* tape mark? */
return MTSE_TMK;
sim_fseek (uptr->fileref, uptr->pos + sizeof (t_tpclnt), SEEK_SET);
break;
case MTUF_F_P7B:
for (sbc = 1, all_eof = 1; (t_addr) sbc <= uptr->pos ; sbc++) {
sim_fseek (uptr->fileref, uptr->pos - sbc, SEEK_SET);
sim_fread (&c, sizeof (uint8), 1, uptr->fileref);
if (ferror (uptr->fileref)) /* error? */
return sim_tape_ioerr (uptr);
if (feof (uptr->fileref)) /* eof? */
return MTSE_EOM;
if ((c & P7B_DPAR) != P7B_EOF)
all_eof = 0;
if (c & P7B_SOR) /* start of record? */
break;
}
uptr->pos = uptr->pos - sbc; /* update position */
*bc = sbc; /* save rec lnt */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* for read */
if (all_eof) /* tape mark? */
return MTSE_TMK;
break;
default:
return MTSE_FMT;
}
return MTSE_OK;
}
/* Read record forward
Inputs:
uptr = pointer to tape unit
buf = pointer to buffer
bc = pointer to returned record length
max = maximum record size
Outputs:
status = operation status
exit condition position
unit unattached unchanged
read error unchanged, PNU set
end of file/medium unchanged, PNU set
invalid record unchanged, PNU set
tape mark updated
data record updated
data record error updated
*/
t_stat sim_tape_rdrecf (UNIT *uptr, uint8 *buf, t_mtrlnt *bc, t_mtrlnt max)
{
uint32 f = MT_GET_FMT (uptr);
t_mtrlnt i, tbc, rbc;
t_addr opos;
t_stat st;
opos = uptr->pos; /* old position */
if (st = sim_tape_rdlntf (uptr, &tbc)) /* read rec lnt */
return st;
*bc = rbc = MTR_L (tbc); /* strip error flag */
if (rbc > max) { /* rec out of range? */
MT_SET_PNU (uptr);
uptr->pos = opos;
return MTSE_INVRL;
}
i = sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr);
uptr->pos = opos;
return sim_tape_ioerr (uptr);
}
for ( ; i < rbc; i++) /* fill with 0's */
buf[i] = 0;
if (f == MTUF_F_P7B) /* p7b? strip SOR */
buf[0] = buf[0] & P7B_DPAR;
return (MTR_F (tbc)? MTSE_RECE: MTSE_OK);
}
/* Read record reverse
Inputs:
uptr = pointer to tape unit
buf = pointer to buffer
bc = pointer to returned record length
max = maximum record size
Outputs:
status = operation status
exit condition position
unit unattached unchanged
read error unchanged
end of file unchanged
end of medium updated
invalid record unchanged
tape mark updated
data record updated
data record error updated
*/
t_stat sim_tape_rdrecr (UNIT *uptr, uint8 *buf, t_mtrlnt *bc, t_mtrlnt max)
{
uint32 f = MT_GET_FMT (uptr);
t_mtrlnt i, rbc, tbc;
t_stat st;
if (st = sim_tape_rdlntr (uptr, &tbc)) /* read rec lnt */
return st;
*bc = rbc = MTR_L (tbc); /* strip error flag */
if (rbc > max) /* rec out of range? */
return MTSE_INVRL;
i = sim_fread (buf, sizeof (uint8), rbc, uptr->fileref);/* read record */
if (ferror (uptr->fileref)) /* error? */
return sim_tape_ioerr (uptr);
for ( ; i < rbc; i++) /* fill with 0's */
buf[i] = 0;
if (f == MTUF_F_P7B) /* p7b? strip SOR */
buf[0] = buf[0] & P7B_DPAR;
return (MTR_F (tbc)? MTSE_RECE: MTSE_OK);
}
/* Write record forward
Inputs:
uptr = pointer to tape unit
buf = pointer to buffer
bc = record length
Outputs:
status = operation status
exit condition position
unit unattached unchanged
write protect unchanged
write error unchanged, PNU set
data record updated
*/
t_stat sim_tape_wrrecf (UNIT *uptr, uint8 *buf, t_mtrlnt bc)
{
uint32 f = MT_GET_FMT (uptr);
t_mtrlnt sbc;
MT_CLR_PNU (uptr);
sbc = MTR_L (bc);
if ((uptr->flags & UNIT_ATT) == 0) /* not attached? */
return MTSE_UNATT;
if (sim_tape_wrp (uptr)) /* write prot? */
return MTSE_WRP;
if (sbc == 0) /* nothing to do? */
return MTSE_OK;
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* set pos */
switch (f) { /* case on format */
case MTUF_F_STD: /* standard */
sbc = MTR_L ((bc + 1) & ~1); /* pad odd length */
case MTUF_F_E11: /* E11 */
sim_fwrite (&bc, sizeof (t_mtrlnt), 1, uptr->fileref);
sim_fwrite (buf, sizeof (uint8), sbc, uptr->fileref);
sim_fwrite (&bc, sizeof (t_mtrlnt), 1, uptr->fileref);
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr);
return sim_tape_ioerr (uptr);
}
uptr->pos = uptr->pos + sbc + (2 * sizeof (t_mtrlnt)); /* move tape */
break;
case MTUF_F_P7B: /* Pierce 7B */
buf[0] = buf[0] | P7B_SOR; /* mark start of rec */
sim_fwrite (buf, sizeof (uint8), sbc, uptr->fileref);
sim_fwrite (buf, sizeof (uint8), 1, uptr->fileref); /* delimit rec */
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr);
return sim_tape_ioerr (uptr);
}
uptr->pos = uptr->pos + sbc; /* move tape */
break;
}
return MTSE_OK;
}
/* Write metadata forward (internal routine) */
t_stat sim_tape_wrdata (UNIT *uptr, uint32 dat)
{
MT_CLR_PNU (uptr);
if ((uptr->flags & UNIT_ATT) == 0) /* not attached? */
return MTSE_UNATT;
if (sim_tape_wrp (uptr)) /* write prot? */
return MTSE_WRP;
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* set pos */
sim_fwrite (&dat, sizeof (t_mtrlnt), 1, uptr->fileref);
if (ferror (uptr->fileref)) { /* error? */
MT_SET_PNU (uptr);
return sim_tape_ioerr (uptr);
}
uptr->pos = uptr->pos + sizeof (t_mtrlnt); /* move tape */
return MTSE_OK;
}
/* Write tape mark */
t_stat sim_tape_wrtmk (UNIT *uptr)
{
if (MT_GET_FMT (uptr) == MTUF_F_P7B) { /* P7B? */
uint8 buf = P7B_EOF; /* eof mark */
return sim_tape_wrrecf (uptr, &buf, 1); /* write char */
}
return sim_tape_wrdata (uptr, MTR_TMK);
}
/* Write end of medium */
t_stat sim_tape_wreom (UNIT *uptr)
{
if (MT_GET_FMT (uptr) == MTUF_F_P7B) /* cant do P7B */
return MTSE_FMT;
return sim_tape_wrdata (uptr, MTR_EOM);
}
/* Write erase gap
Inputs:
uptr = pointer to tape unit
gaplen = length of gap in tenths of an inch
bpi = current recording density in bytes per inch
Outputs:
status = operation status
exit condition position
------------------ ------------------
unit unattached unchanged
unsupported format unchanged
write protected unchanged
read error unchanged, PNU set
write error unchanged, PNU set
gap written updated
An erase gap is represented in the tape image file by a special metadata
value. This value is chosen so that it is still recognizable even if it has
been "cut in half" by a subsequent data overwrite that does not end on a
metadatum-sized boundary. In addition, a range of metadata values are
reserved for detection in the reverse direction. Erase gaps are supported
only in SIMH tape format.
This implementation supports erasing gaps in the middle of a populated tape
image and will always produce a valid image. It also produces valid images
when overwriting gaps with data records, with one exception: a data write
that leaves only two bytes of gap remaining will produce an invalid tape.
This limitation is deemed acceptable, as it is analogous to the existing
limitation that data records cannot overwrite other data records without
producing an invalid tape.
Because SIMH tape images do not carry physical parameters (e.g., recording
density), overwriting a tape image file containing gap metadata is
problematic if the density setting is not the same as that used during
recording. There is no way to establish a gap of a certain length
unequivocally in an image file, so this implementation establishes a gap of a
certain number of bytes that reflect the desired gap length at the bpi used
during writing.
To write an erase gap, the implementation uses one of two approaches,
depending on whether or not the current tape position is at EOM. Erasing at
EOM presents no special difficulties; gap metadata markers are written for
the prescribed number of bytes. If the tape is not at EOM, then erasing must
take into account the existing record structure to ensure that a valid tape
image is maintained.
The general approach is to erase for the nominal number of bytes but to
increase that length, if necessary, to ensure that a partially overwritten
data record at the end of the gap can be altered to maintain validity.
Because the smallest legal tape record requires space for two metadata
markers plus two data bytes, an erasure that would leave less than that
is increased to consume the entire record. Otherwise, the final record is
truncated appropriately.
When reading in either direction, gap metadata markers are ignored (skipped)
until a record length header, EOF marker, EOM marker, or physical EOF is
encountered. Thus, tape images containing gap metadata are transparent to
the calling simulator.
The permissibility of data record lengths that are not multiples of the
metadatum size presents a difficulty when reading. If such an "odd length"
record is written over a gap, half of a metadata marker will exist
immediately after the trailing record length.
This condition is detected when reading forward by the appearance of a
"reversed" marker. The value appears reversed because the value is made up
of half of one marker and half of the next. This is handled by seeking
forward two bytes to resync (the stipulation above that the overwrite cannot
leave only two bytes of gap means that at least one "whole" metadata marker
will follow). Reading in reverse presents a more complex problem, because
half of the marker is from the preceding trailing record length marker and
therefore could be any of a range of values. However, that range is
restricted by the SIMH tape specification requirement that record length
metadata values must have bits 30:24 set to zero. This allows unambiguous
detection of the condition.
The value chosen for gap metadata and the values reserved for "half-gap"
detection are:
0xFFFFFFFE - primary gap value
0xFFFEFFFF - reserved (indicates half-gap in forward reads)
0xFFFF0000:0xFFFF00FF - reserved (indicates half-gap in reverse reads)
0xFFFF8000:0xFFFF80FF - reserved (indicates half-gap in reverse reads)
*/
t_stat sim_tape_wrgap (UNIT *uptr, uint32 gaplen, uint32 bpi)
{
t_stat st;
t_mtrlnt meta, sbc, new_len, rec_size;
t_addr gap_pos = uptr->pos;
uint32 file_size, marker_count;
uint32 format = MT_GET_FMT (uptr);
uint32 gap_alloc = 0; /* gap allocated from tape */
int32 gap_needed = (gaplen * bpi) / 10; /* gap remainder still needed */
const uint32 meta_size = sizeof (t_mtrlnt); /* bytes per metadatum */
const uint32 min_rec_size = 2 + sizeof (t_mtrlnt) * 2; /* smallest data record size */
MT_CLR_PNU (uptr);
if ((uptr->flags & UNIT_ATT) == 0) /* not attached? */
return MTSE_UNATT;
if (format != MTUF_F_STD) /* not SIMH fmt? */
return MTSE_FMT;
if (sim_tape_wrp (uptr)) /* write protected? */
return MTSE_WRP;
file_size = sim_fsize (uptr->fileref); /* get file size */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* position tape */
/* Read tape records and allocate to gap until amount required is consumed.
Read next metadatum from tape:
- EOF or EOM: allocate remainder of bytes needed.
- TMK or GAP: allocate sizeof(metadatum) bytes.
- Reverse GAP: allocate sizeof(metadatum) / 2 bytes.
- Data record: see below.
Loop until bytes needed = 0.
*/
do {
sim_fread (&meta, meta_size, 1, uptr->fileref); /* read metadatum */
if (ferror (uptr->fileref)) { /* read error? */
uptr->pos = gap_pos; /* restore original position */
MT_SET_PNU (uptr); /* position not updated */
return sim_tape_ioerr (uptr); /* translate error */
}
else
uptr->pos = uptr->pos + meta_size; /* move tape over datum */
if (feof (uptr->fileref) || (meta == MTR_EOM)) { /* at eof or eom? */
gap_alloc = gap_alloc + gap_needed; /* allocate remainder */
gap_needed = 0;
}
else if ((meta == MTR_GAP) || (meta == MTR_TMK)) { /* gap or tape mark? */
gap_alloc = gap_alloc + meta_size; /* allocate marker space */
gap_needed = gap_needed - meta_size; /* reduce requirement */
}
else if (meta == MTR_FHGAP) { /* half gap? */
uptr->pos = uptr->pos - meta_size / 2; /* backup to resync */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* position tape */
gap_alloc = gap_alloc + meta_size / 2; /* allocate marker space */
gap_needed = gap_needed - meta_size / 2; /* reduce requirement */
}
else if (uptr->pos +
MTR_L (meta) + meta_size > file_size) { /* rec len out of range? */
gap_alloc = gap_alloc + gap_needed; /* presume overwritten tape */
gap_needed = 0; /* allocate remainder */
}
/* Allocate a data record:
- Determine record size in bytes (including metadata)
- If record size - bytes needed < smallest allowed record size,
allocate entire record to gap, else allocate needed amount and
truncate data record to reflect remainder.
*/
else { /* data record */
sbc = MTR_L (meta); /* get record data length */
rec_size = ((sbc + 1) & ~1) + meta_size * 2; /* overall size in bytes */
if (rec_size < gap_needed + min_rec_size) { /* rec too small? */
uptr->pos = uptr->pos - meta_size + rec_size; /* position past record */
sim_fseek (uptr->fileref, uptr->pos, SEEK_SET); /* move tape */
gap_alloc = gap_alloc + rec_size; /* allocate record */
gap_needed = gap_needed - rec_size; /* reduce requirement */
}
else { /* record size OK */
uptr->pos = uptr->pos - meta_size + gap_needed; /* position to end of gap */
new_len = MTR_F (meta) | (sbc - gap_needed); /* truncate to new len */
st = sim_tape_wrdata (uptr, new_len); /* write new rec len */
if (st != MTSE_OK) { /* write OK? */
uptr->pos = gap_pos; /* restore orig pos */
return st; /* PNU was set by wrdata */
}
uptr->pos = uptr->pos + sbc - gap_needed; /* position to end of data */
st = sim_tape_wrdata (uptr, new_len); /* write new rec len */
if (st != MTSE_OK) { /* write OK? */
uptr->pos = gap_pos; /* restore orig pos */
return st; /* PNU was set by wrdata */
}
gap_alloc = gap_alloc + gap_needed; /* allocate remainder */
gap_needed = 0;
}
}
}
while (gap_needed > 0);
uptr->pos = gap_pos; /* reposition to gap start */
if (gap_alloc & (meta_size - 1)) { /* gap size "odd?" */
st = sim_tape_wrdata (uptr, MTR_FHGAP); /* write half gap marker */
if (st != MTSE_OK) { /* write OK? */
uptr->pos = gap_pos; /* restore orig pos */
return st; /* PNU was set by wrdata */
}
uptr->pos = uptr->pos - meta_size / 2; /* realign position */
gap_alloc = gap_alloc - 2; /* decrease gap to write */
}
marker_count = gap_alloc / meta_size; /* count of gap markers */
do {
st = sim_tape_wrdata (uptr, MTR_GAP); /* write gap markers */
if (st != MTSE_OK) { /* write OK? */
uptr->pos = gap_pos; /* restore orig pos */
return st; /* PNU was set by wrdata */
}
}
while (--marker_count > 0);
return MTSE_OK;
}
/* Space record forward */
t_stat sim_tape_sprecf (UNIT *uptr, t_mtrlnt *bc)
{
t_stat st;
st = sim_tape_rdlntf (uptr, bc); /* get record length */
*bc = MTR_L (*bc);
return st;
}
/* Space record reverse */
t_stat sim_tape_sprecr (UNIT *uptr, t_mtrlnt *bc)
{
t_stat st;
if (MT_TST_PNU (uptr)) {
MT_CLR_PNU (uptr);
*bc = 0;
return MTSE_OK;
}
st = sim_tape_rdlntr (uptr, bc); /* get record length */
*bc = MTR_L (*bc);
return st;
}
/* Rewind tape */
t_stat sim_tape_rewind (UNIT *uptr)
{
uptr->pos = 0;
MT_CLR_PNU (uptr);
return MTSE_OK;
}
/* Reset tape */
t_stat sim_tape_reset (UNIT *uptr)
{
MT_CLR_PNU (uptr);
return SCPE_OK;
}
/* Test for BOT */
t_bool sim_tape_bot (UNIT *uptr)
{
uint32 f = MT_GET_FMT (uptr);
return (uptr->pos <= fmts[f].bot)? TRUE: FALSE;
}
/* Test for end of tape */
t_bool sim_tape_eot (UNIT *uptr)
{
return (uptr->capac && (uptr->pos >= uptr->capac))? TRUE: FALSE;
}
/* Test for write protect */
t_bool sim_tape_wrp (UNIT *uptr)
{
return (uptr->flags & MTUF_WRP)? TRUE: FALSE;
}
/* Process I/O error */
t_stat sim_tape_ioerr (UNIT *uptr)
{
perror ("Magtape library I/O error");
clearerr (uptr->fileref);
return MTSE_IOERR;
}
/* Set tape format */
t_stat sim_tape_set_fmt (UNIT *uptr, int32 val, char *cptr, void *desc)
{
uint32 f;
if (uptr == NULL)
return SCPE_IERR;
if (cptr == NULL)
return SCPE_ARG;
for (f = 0; f < MTUF_N_FMT; f++) {
if (fmts[f].name && (strcmp (cptr, fmts[f].name) == 0)) {
uptr->flags = (uptr->flags & ~MTUF_FMT) |
(f << MTUF_V_FMT) | fmts[f].uflags;
return SCPE_OK;
}
}
return SCPE_ARG;
}
/* Show tape format */
t_stat sim_tape_show_fmt (FILE *st, UNIT *uptr, int32 val, void *desc)
{
int32 f = MT_GET_FMT (uptr);
if (fmts[f].name)
fprintf (st, "%s format", fmts[f].name);
else fprintf (st, "invalid format");
return SCPE_OK;
}
/* Map a TPC format tape image */
uint32 sim_tape_tpc_map (UNIT *uptr, t_addr *map)
{
t_addr tpos;
t_tpclnt bc;
uint32 i, objc;
if ((uptr == NULL) || (uptr->fileref == NULL))
return 0;
for (objc = 0, tpos = 0;; ) {
sim_fseek (uptr->fileref, tpos, SEEK_SET);
i = sim_fread (&bc, sizeof (t_tpclnt), 1, uptr->fileref);
if (i == 0)
break;
if (map)
map[objc] = tpos;
objc++;
tpos = tpos + ((bc + 1) & ~1) + sizeof (t_tpclnt);
}
if (map) map[objc] = tpos;
return objc;
}
/* Find the preceding record in a TPC file */
t_addr sim_tape_tpc_fnd (UNIT *uptr, t_addr *map)
{
uint32 lo, hi, p;
if (map == NULL)
return 0;
lo = 0;
hi = uptr->hwmark - 1;
do {
p = (lo + hi) >> 1;
if (uptr->pos == map[p])
return ((p == 0)? map[p]: map[p - 1]);
else if (uptr->pos < map[p])
hi = p - 1;
else lo = p + 1;
}
while (lo <= hi);
return ((p == 0)? map[p]: map[p - 1]);
}
/* Set tape capacity */
t_stat sim_tape_set_capac (UNIT *uptr, int32 val, char *cptr, void *desc)
{
extern uint32 sim_taddr_64;
t_addr cap;
t_stat r;
if ((cptr == NULL) || (*cptr == 0))
return SCPE_ARG;
if (uptr->flags & UNIT_ATT)
return SCPE_ALATT;
cap = (t_addr) get_uint (cptr, 10, sim_taddr_64? 2000000: 2000, &r);
if (r != SCPE_OK)
return SCPE_ARG;
uptr->capac = cap * ((t_addr) 1000000);
return SCPE_OK;
}
/* Show tape capacity */
t_stat sim_tape_show_capac (FILE *st, UNIT *uptr, int32 val, void *desc)
{
if (uptr->capac) {
if (uptr->capac >= (t_addr) 1000000)
fprintf (st, "capacity=%dMB", (uint32) (uptr->capac / ((t_addr) 1000000)));
else if (uptr->capac >= (t_addr) 1000)
fprintf (st, "capacity=%dKB", (uint32) (uptr->capac / ((t_addr) 1000)));
else fprintf (st, "capacity=%dB", (uint32) uptr->capac);
}
else fprintf (st, "unlimited capacity");
return SCPE_OK;
}
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