sigma: Correct recognition of pending DP seek interrupt.

This corrects an error that caused SIO reject when SIO occured before
a pending seek interrupt on a different device.
 - Move the interrupt pending test from sigma_io.c into each device.
 - Make the sigma_dp.c test a special case that looks for pending
   seek interrupts.

sigma/sigma_coc.c

@@ -277,7 +277,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = mux_tio_status ();                      /* get status */
-        if ((*dvst & DVS_CST) == 0) {                   /* ctrl idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+              *dvst |= (CC2 << DVT_V_CC);               /* SIO fails */
+          else if ((*dvst & DVS_CST) == 0) {            /* ctrl idle? */
             muxc_cmd = MUXC_INIT;                       /* start dev thread */
             sim_activate (&mux_unit[MUXC], chan_ctl_time);
             }

sigma/sigma_dk.c

@@ -170,7 +170,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = dk_tio_status (un);                     /* get status */
-        if ((*dvst & (DVS_CST|DVS_DST)) == 0) {         /* ctrl + dev idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & (DVS_CST|DVS_DST)) == 0) {    /* ctrl + dev idle? */
             dk_cmd = DKS_INIT;                          /* start dev thread */
             sim_activate (&dk_unit[un], chan_ctl_time);
             }

sigma/sigma_dp.c

@@ -47,6 +47,16 @@
    one for timing asynchronous seek completions. The controller will not
    start a new operation is it is busy (any of the main units active) or if
    the target device is busy (its seek unit is active).
+ 
+   The DP's seek interrupt has a unique feature: it comes and goes, lasting only
+   a sector's time; and it gets "knocked down" by any SIO to a different unit.
+   Therefore, the SIO interrupt check is complicated.
+
+   1. If there's a controller interrupt, the SIO fails.
+   2. If there's a seek interrupt on the selected unit, the SIO fails.
+   3. All other seek interrupts are "knocked down" and rescheduled for
+      some time "in the future."
+   4. The SIO completes normally.
 */
 
 #include "sigma_io_defs.h"
@@ -589,6 +599,18 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = dp_tio_status (cidx, un);               /* get status */
+        if ((chan_chk_chi (dva) >= 0) ||                /* channel int pending? */
+            (dp_ctx[cidx].dp_ski & (1u << un))) {       /* seek int on sel unit? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+            break;
+            }
+        for (i = 0; i < DP_NUMDR; i++) {                /* knock down other seek ints */
+            if (dp_ctx[cidx].dp_ski & (1u << i)) {      /* seek int on unit? */
+                dp_clr_ski (cidx, i);                   /* knock it down */
+                sim_activate (&dp_unit[i + DP_SEEK], chan_ctl_time * 10);
+                dp_unit[i + DP_SEEK].UCMD = DSC_SEEKW;  /* resched interrupt */
+                }
+            }
         if ((*dvst & (DVS_CST|DVS_DST)) == 0) {         /* ctrl + dev idle? */
             uptr->UCMD = DPS_INIT;                      /* start dev thread */
             sim_activate (uptr, chan_ctl_time);

sigma/sigma_io.c

@@ -353,11 +353,6 @@ if (!io_init_inst (rn, ad, ch, dev, R[0])) {            /* valid inst? */
     CC |= CC1|CC2;
     return 0;
     }
-if (chan[ch].chf[dev] & CHF_INP) {                      /* int pending? */
-    chan[ch].disp[dev] (OP_TIO, ad, &dvst);             /* get status */
-    CC |= (CC2 | io_set_status (rn, ch, dev, dvst, 0)); /* set status */
-    return 0;
-    }
 st = chan[ch].disp[dev] (OP_SIO, ad, &dvst);            /* start I/O */
 CC |= io_set_status (rn, ch, dev, dvst, 0);             /* set status */
 if (CC & cpu_tab[cpu_model].iocc)                       /* error? */
@@ -806,7 +801,7 @@ if (chan[ch].chi[dev] & CHI_CTL)                        /* ctl int pending? */
 else return -1;
 }
 
-/* Set device interrupt */
+/* Set, check device interrupt */
 
 void chan_set_dvi (uint32 dva)
 {
@@ -817,6 +812,16 @@ chan[ch].chf[dev] |= CHF_INP;                           /* int pending */
 return;
 }
 
+t_bool chan_chk_dvi (uint32 dva)
+{
+uint32 ch = DVA_GETCHAN (dva);                          /* get ch, dev */
+uint32 dev = DVA_GETDEV (dva);
+
+if ((chan[ch].chf[dev] & CHF_INP) != 0)
+    return TRUE;
+return FALSE;
+}
+
 /* Called by device reset to reset channel registers */
 
 t_stat chan_reset_dev (uint32 dva)

sigma/sigma_io_defs.h

@@ -252,6 +252,7 @@ void chan_set_chi (uint32 dva, uint32 fl);
 void chan_set_dvi (uint32 dva);
 int32 chan_clr_chi (uint32 dva);
 int32 chan_chk_chi (uint32 dva);
+t_bool chan_chk_dvi (uint32 dva);
 uint32 chan_end (uint32 dva);
 uint32 chan_uen (uint32 dva);
 uint32 chan_RdMemB (uint32 dva, uint32 *dat);

sigma/sigma_lp.c

@@ -180,7 +180,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = lp_tio_status ();                       /* get status */
-        if ((*dvst & DVS_DST) == 0) {                   /* idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & DVS_DST) == 0) {              /* idle? */
             lp_cmd = LPS_INIT;                          /* start dev thread */
             sim_activate (&lp_unit, chan_ctl_time);
             }

sigma/sigma_mt.c

@@ -237,7 +237,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = mt_tio_status (un);                     /* get status */
-        if ((*dvst & (DVS_CST|DVS_DST)) == 0) {         /* ctrl + dev idle? */
+         if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & (DVS_CST|DVS_DST)) == 0) {    /* ctrl + dev idle? */
             uptr->UCMD = MCM_INIT;                      /* start dev thread */
             sim_activate (uptr, chan_ctl_time);
             }

sigma/sigma_pt.c

@@ -119,7 +119,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = pt_tio_status ();                       /* get status */
-        if ((*dvst & DVS_DST) == 0) {                   /* idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & DVS_DST) == 0) {              /* idle? */
             pt_cmd = PTS_INIT;                          /* start dev thread */
             sim_activate (&pt_unit[PTR], chan_ctl_time);
             }

sigma/sigma_rad.c

@@ -211,7 +211,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = rad_tio_status (un);                    /* get status */
-        if ((*dvst & (DVS_CST|DVS_DST)) == 0) {         /* ctrl + dev idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & (DVS_CST|DVS_DST)) == 0) {    /* ctrl + dev idle? */
             rad_cmd = RADS_INIT;                        /* start dev thread */
             sim_activate (&rad_unit[un], chan_ctl_time);
             }

sigma/sigma_tt.c

@@ -134,7 +134,9 @@ switch (op) {                                           /* case on op */
 
     case OP_SIO:                                        /* start I/O */
         *dvst = tt_tio_status ();                       /* get status */
-        if ((*dvst & DVS_DST) == 0) {                   /* idle? */
+        if (chan_chk_dvi (dva))                         /* int pending? */
+            *dvst |= (CC2 << DVT_V_CC);                 /* SIO fails */
+        else if ((*dvst & DVS_DST) == 0) {              /* idle? */
             tt_cmd = TTS_INIT;                          /* start dev thread */
             sim_activate (&tt_unit[TTO], chan_ctl_time);
             }