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PDP11: Revert DZ device to prior version.

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The code in 3.12-2 is only part of a complete solution and thus merely
hangs the device/processor.

The reverted version wouldn't normally have the problem since the
normally partial code was trying to fix since I/O completion happens
right in dz_wr().  However, the "complete it immediately" model could
logically lose data if the sending side were driven harder than the TMXR
TCP transport was able to deliver data to the TCP session.  The easiest
answer is to revert to the earlier v3 DZ code since at least that worked
almost all of the time.

The right answer would be to only signal the transmit completion
interrupt if the transmit didn't end up getting buffered and if it did
get buffered (and not successfully flushed), then schedule a separate
unit to retry the pending output until it actually made it to the TCP
wire.  That separate unit would then signal the interrupt for the line
indicated in the CSR and mark CSR_TRDY.

This is more change to realize relatively little value so simply revert
and be done.
This commit is contained in:
Mark Pizzolato
2022-09-04 18:09:37 -06:00
parent 49fb037eba
commit 7a68c268b9
1 changed files with 12 additions and 16 deletions
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28
PDP11/pdp11_dz.c
View File

@@ -1,6 +1,6 @@
/* pdp11_dz.c: DZ11 terminal multiplexor simulator
Copyright (c) 2001-2020, Robert M Supnik
Copyright (c) 2001-2008, 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"),
@@ -25,7 +25,6 @@
dz DZ11 terminal multiplexor
14-Feb-20 RMS Fixed race condition for multiple transmitters (Mark Pizzolato)
29-Dec-08 RMS Added MTAB_NC to SET LOG command (Walter Mueller)
19-Nov-08 RMS Revised for common TMXR show routines
18-Jun-07 RMS Added UNIT_IDLE flag
@@ -374,8 +373,7 @@ switch ((PA >> 1) & 03) { /* case on PA<2:1> */
if (c >= 0) /* store char */
tmxr_putc_ln (lp, c);
tmxr_poll_tx (&dz_desc); /* poll output */
dz_csr[dz] &= ~CSR_TRDY; /* clear TRDY for now */
dz_update_xmti(); /* update int */
dz_update_xmti (); /* update int */
}
break;
}
@@ -476,18 +474,16 @@ void dz_update_xmti (void)
int32 dz, linemask, i, j, line;
for (dz = 0; dz < DZ_MUXES; dz++) { /* loop thru muxes */
if ((dz_csr[dz] & CSR_TRDY) == 0) { /* xmiting? */
linemask = dz_tcr[dz] & DZ_LMASK; /* enabled lines */
dz_csr[dz] &= ~CSR_TRDY; /* assume not rdy */
j = CSR_GETTL (dz_csr[dz]); /* start at current */
for (i = 0; i < DZ_LINES; i++) { /* loop thru lines */
j = (j + 1) & DZ_LNOMASK; /* next line */
line = (dz * DZ_LINES) + j; /* get line num */
if ((linemask & (1 << j)) && dz_ldsc[line].xmte) {
CSR_PUTTL(dz_csr[dz], j); /* put ln in csr */
dz_csr[dz] |= CSR_TRDY; /* set xmt rdy */
break;
}
linemask = dz_tcr[dz] & DZ_LMASK; /* enabled lines */
dz_csr[dz] &= ~CSR_TRDY; /* assume not rdy */
j = CSR_GETTL (dz_csr[dz]); /* start at current */
for (i = 0; i < DZ_LINES; i++) { /* loop thru lines */
j = (j + 1) & DZ_LNOMASK; /* next line */
line = (dz * DZ_LINES) + j; /* get line num */
if ((linemask & (1 << j)) && dz_ldsc[line].xmte) {
CSR_PUTTL (dz_csr[dz], j); /* put ln in csr */
dz_csr[dz] |= CSR_TRDY; /* set xmt rdy */
break;
}
}
if ((dz_csr[dz] & CSR_TIE) && (dz_csr[dz] & CSR_TRDY)) /* ready plus int? */