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emdev.h: mt backspace at EOT kept returning EOT

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Jim
2011-11-03 17:03:25 -04:00
parent 6198e38d70
commit c6d4fd1724
1 changed files with 45 additions and 31 deletions
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76
emdev.h
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@@ -664,38 +664,41 @@ readasr:
These names are usually just links to the actual tape file.
Tape status word bits (MSB to LSB):
1 = Vertical Parity Error
2 = Runaway
3 = CRC Error
4 = LRCC Error
5 = False Gap or Insufficient DMX Range
6 = Uncorrectable Read Error
7 = Raw Erorr
8 = Illegal Command
9 = Selected Tape Ready (online and not rewinding)
10 = Selected Tape Online
11 = Selected Tape is at End Of Tape (EOT)
12 = Selected Tape is Rewinding
13 = Selected Tape is at Beginning Of Tape (BOT)
14 = Selected Tape is Write Protected
15 = DMX Overrun
16 = Rewind Interrupt
1 0x8000 = Vertical Parity Error
2 0x4000 = Runaway
3 0x2000 = CRC Error
4 0x1000 = LRCC Error
5 0x0800 = False Gap or Insufficient DMX Range
6 0x0400 = Uncorrectable Read Error
7 0x0200 = Raw Error
8 0x0100 = Illegal Command (XXX: File Mark too?)
9 0x0080 = Selected Tape Ready (online and not rewinding)
10 0x0040 = Selected Tape Online
11 0x0020 = Selected Tape is at End Of Tape (EOT)
12 0x0010 = Selected Tape is Rewinding
13 0x0008 = Selected Tape is at Beginning Of Tape (BOT)
14 0x0004 = Selected Tape is Write Protected
15 0x0002 = DMX Overrun
16 0x0001 = Rewind Interrupt
OTA '01 Motion control A-register bits:
1 = Select Tape Only
2 = 0 for File operation, 1 for Record operation
3 = 1 for Space operation
4 = 1 for Read & Correct
5 = 1 for 7-track
6 = 1 for 9-track
7 = unused
8 = 1 for 2 chars/word, 0 for 1 char/word (not supported here)
9-11 = motion: 100 = Forward, 010 = Reverse, 001 = Rewind
12 = 1 for Write
13 = 1 for Unit 0
14 = 1 for Unit 1
15 = 1 for Unit 2
16 = 1 for Unit 3
1 0x8000 = Select Tape Only
2 0x4000 = 0 for File operation, 1 for Record operation
3 0x2000 = 1 for Space operation
4 0x1000 = 1 for Read & Correct
5 0x800 = 1 for 7-track
6 0x400 = 1 for 9-track
7 0x200 = unused
8 0x100 = 1 for 2 chars/word, 0 for 1 char/word (not supported here)
9-11 = motion:
0x80 = Forward
0x40 = Reverse
0x20 = Rewind
12 0x10 = 1 for Write
13 0x8 = Unit 0
14 0x4 = Unit 1
15 0x2 = Unit 2
16 0x1 = Unit 3
If the tape device file is empty, then BOT and EOT occur together.
But, this doesn't happen with real magtapes, and some Prime software
@@ -708,7 +711,7 @@ int mtread (int fd, unsigned short *iobuf, int nw, int cmd, int *mtstat) {
unsigned char buf[4];
int n,reclen,reclen2,bytestoread;
TRACE(T_TIO, " mtread, nw=%d, initial tape status is 0x%04x\n", nw, *mtstat);
TRACE(T_TIO, " mtread, fpos=%u, nw=%d, cmd=0x%04x, status is 0x%04x\n", (unsigned int) lseek(fd, 0, SEEK_CUR), nw, cmd, *mtstat);
if (cmd & 0x80) { /* forward motion */
if (*mtstat & 0x20) /* already at EOT, can't read */
return 0;
@@ -823,6 +826,17 @@ fmterr:
return 0;
}
/* if we were at EOT, clear EOT; next read will get EOT again */
if (*mtstat & 0x20) {
*mtstat &= ~0x20;
return 0;
}
/* now we're not at EOT */
*mtstat &= ~0x20;
/* backup 4 bytes, read reclen */
if (lseek(fd, -4, SEEK_CUR) == -1) {