icycle()
{
int op,a1,a2,x1,x2,i1,i2,setting,setmask,onemask,oldmask;
int ecd; /* Error Code */
/* setjmp(svstck) to save stack for return */
/* from possible segment and page faults */
if((ecd=setjmp(svstck)) != 0)
{
goto except;
}
ir = pm[cmap(pc)];
pc++;
/* extract instruction fields into op, a1, a2; */
/* generate the eff. virtual addresses v1, v2 */
/* using the algorithm in the Reference Manual */
op = extract(ir,24,6);
a1 = extract(ir,12,10);
a2 = extract(ir,0,10);
x1 = extract(ir,22,1);
x2 = extract(ir,10,1);
i1 = extract(ir,23,1);
i2 = extract(ir,11,1);
v1 = a1;
v2 = a2; /* address field forms initial value */
if (i1 == 1) v1 = pm[dmap(v1)]; /* if indirection, get ind. loc */
if (i2 == 1) v2 = pm[dmap(v2)];
if (x1 == 1) v1 = v1 + xr; /* if indexing specified, add xr */
if (x2 == 1) v2 = v2 + xr;
switch(op)
{
case 1: gr = pm[dmap(v1)]; /* gr load */
break;
case 2: pm[dmap(v1)] = gr; /* gr store */
break;
case 3: xr = pm[dmap(v1)]; /* xr load */
break;
case 4: pm[dmap(v1)] = xr; /* xr store */
break;
case 5: sr = pm[dmap(v1)]; /* sr load */
break;
case 6: pm[dmap(v1)] = sr; /* sr store */
break;
case 8: pm[dmap(v2)] = pm[dmap(v1)]; /* copy */
break;
case 9: pm[dmap(v2)] += pm[dmap(v1)]; /* add */
break;
case 10: pm[dmap(v2)] -= pm[dmap(v1)]; /* subtract */
break;
case 11: pm[dmap(v2)] *= pm[dmap(v1)]; /* multiply */
break;
case 12: /* Divide */
if (pm[dmap(v1)] == 0)
{
ecd = ARITFLT;
printf ("\nDivide Fault\n");
goto except;
}
else
pm[dmap(v2)] /= pm[dmap(v1)];
break;
case 13: pm[dmap(v2)] &= pm[dmap(v1)]; /* and */
break;
case 14: pm[dmap(v2)] |= pm[dmap(v1)]; /* or */
break;
case 16: pc = v1; /* go to */
break;
case 17: if (pm[dmap(v1)] != pm[dmap(v2)]) pc++; /* if = */
break;
case 18: if (pm[dmap(v1)] == pm[dmap(v2)]) pc++; /* if != */
break;
case 19: if (pm[dmap(v1)] >= pm[dmap(v2)]) pc++; /* if < */
break;
case 20: if (pm[dmap(v1)] < pm[dmap(v2)]) pc++; /* if >= */
break;
case 21: xr++; /* loop */
if (xr < pm[dmap(v1)]) pc = v2;
break;
case 22: sr = pc;
pc = v1; /* call */
break;
case 23: pc = sr + pm[dmap(v1)]; /* return */
break;
case 26: xr = v1; /* xr set */
break;
case 27: pm[dmap(v2)] = v1; /* vm set */
break;
case 28: pm[dmap(v2)] = extract(pm[dmap(v1 + gr/4)],(gr%4)*8,8); /* get byte */
break;
case 29: setting = extract(pm[dmap(v2)],0, 8); /* set byte */
/* Byte want to set in pos with 0s other */
setmask = setting << (gr%4)*8;
onemask = 0xFFFFFFFF - (0xFF << (gr%4) * 8); /* mask with ones 'cept 0's in pos. */
oldmask = pm[dmap(v1+(gr/4))] & onemask; /* old value of word with 0's in pos */
pm[dmap(v1+(gr/4))] = oldmask | setmask; /* new word to write to memory */
break;
case 31: ; /* noop */
break;
case 32: hlt = TRUE; /* halt */
break;
case 33: /* error */
hlt = TRUE;
/* A1 serves as error code */
printf("\n ERROR: %x\n",a1);
break;
case 34: /* PmVmCp -- Primary Mem V Mem copy */
if (md < 0) goto illins;
pm [dmap(v2)] = pm [v1];
break;
case 35: /* VmPmCp */
if (md < 0) goto illins;
pm [v2] = pm[dmap(v1)];
break;
case 36: /* Arm */
if (md < 0) goto illins;
ar |= pm [dmap(v1)];
break;
case 37: /* Disarm */
if (md < 0) goto illins;
ar &= (-1-pm[dmap(v1)]);
break;
case 38: /* OS Call */
if (md > 0) goto illins;
ie |= EBIT; /* set exception */
pm [sp+PSR_ECD] = a1; /* OS Call Number */
break;
case 40: /* Floppy IO */
if (md < 0) goto illins;
if (pm[LCL_FCP] < 0) { hlt = TRUE; break; }
floppy_io ();
break;
case 41: /* Disk IO */
if (md < 0) goto illins;
if (pm[LCL_DCP] < 0) { hlt = TRUE; break; }
disk_io ();
break;
case 42: /* Print IO */
/* Advance one line and printf pm[v1] */
if (md < 0) goto illins;
fprintf (printer,"\t%s\t%8x\n",LP_STR,pm[v1]);
fflush(printer);
break;
case 43: /* Log */
if (md < 0) goto illins;
log (v1, v2);
break;
/* Cases 44 and 45 not written yet */
case 44: /* TTY IN */
if (md < 0) goto illins;
break;
case 45: /* TTY Out */
if (md < 0) goto illins;
break;
/*********************************************/
case 48: /* Head Record */
if (moverec(v1,v2,pm[dmap(v1)]))
pc++;
break;
case 49: /* Move Record */
if (moverec (v1, v2, xr))
pc++;
break;
case 50: /* Insert Record */
if (xr < 0) break;
insrec (v1, pm[dmap(v2)], xr);
pc++;
break;
case 51: /* Find Record */
while (((pm[dmap(v1)+1] & pm[dmap(v2)]) != gr) && (pm[dmap(v1)] > 0))
{
v1 = pm[dmap(v1)];
}
if ((pm[dmap(v1)+1] & pm[dmap(v2)]) == gr)
{
xr = v1;
pc++;
}
break;
case 53: /* Allocate */
if (allocate(v1,v2,gr)) pc++;
break;
case 54: /* DeAllocate */
if (deallocate(v1,v2,gr)) pc++;
break;
case 56: /* SP Load */
if (md < 0) goto illins;
sp = pm [dmap(v1)];
break;
case 57: /* Switch Process */
if (md < 0) goto illins;
swcontxt (v1, v2);
break;
case 60: /* Send Message */
if (md < 0) goto illins;
if (pm [LCL_MSF] > 0)
send_mesg ();
break;
case 61: /* Receive Message */
if (md < 0) goto illins;
if (pm[dmap(sp + PSR_MSQ)] > 0)
recv_mesg ();
else
{
/* reset M bit and switch to scheduler */
pc--;
pm[dmap(sp + PSR_STW)] |= MBIT;
swcontxt (pm[LCL_SCH], pc);
}
break;
default: hlt = TRUE; /* Unused Op */
break;
} /* End Case */
goto realtm ; /* Ready for real time section */
/* Real Time Code */
realtm:
pm [LCL_TOD]++; /* Increment Time of Day */
pm [LCL_ALM]++; /* Increment Alarm */
if (pm [LCL_ALM] == 0)
ie |= ABIT; /* Set the Alarm */
if (sp > 0)
pm [sp+PSR_CPT]++; /* Increment CPU time */
if (fbsyrd) /* Floppy busy? Get 2 wrds */
{
/* Read two words */
/* is it pointing to the correct place? */
if (fread (&pm[ftx], WD_B, 2, floppy) != 2)
{
fbsyrd = 0;
pc --;
}
else
{
ftx += 2;
if (ftx == ftul)
{ fbsyrd = 0; ie |= FBIT; md &= ~(1<<FBIT); }
}
}
if (dbsyrd) /* Disk Busy Reading ? Get 2 Words */
{
recv (dmasock, &pm[dtx], 2*WD_B, 0);
dtx += 2;
if (dtx == dtul)
{ dbsyrd = 0; ie |= DBIT; md &= ~(1<<DBIT); }
}
else
if (dbsywr) /* Disk Writing (and not reading) Send 2 words */
{
write (dmasock, &pm[dtx], 2*WD_B);
dtx += 2;
if (dtx == dtul)
{ dbsywr = 0; ie |= DBIT; md &= ~(1<<DBIT); }
}
/* Interrupt Handling */
if (ie != 0 && ar < 0)
{
int intr;
int md_sign;
int md_val;
/* If something else running and this is not a greater one ignore for now */
if ((extract (md,0,WD_L-1) != 0) && (md <= ie)) return; /* Go away */
/* Get sign bit */
md_sign = (extract (md,(WD_L-1),1)) << (WD_L-1) ;
/* Get the rightmost interrupt and make sure it can execute */
for (i=0; i< LEV_N; i++)
{
if ( (intr = (ffs (ie)-1)) != -1) /* Find the int */
if (extract (ar,intr,1)) /* Is it armed? */
{
if (sp > 0)
/* Set the "return to" value to SP */
pm [LCL_ITV + (2*intr) +1] = sp;
else
{ hlt = TRUE ; break ; }
ie &= ~(1<<intr); /* Clear the int */
swcontxt (pm[LCL_ITV+(2*intr)], pc); /* Switch to it */
md = (1 << intr); /* Set mode register */
/* md = ((1<<intr) | md_sign); /* Set mode register */
break;
}
}
}
return;
/* Illegal instruction */
illins:
ecd = INSTFLT;
printf ("\n\nIll Ins ECD : %x\n\n", ecd);
goto except;
/* Exception */
except:
ie |= EBIT;
printf ("\nException Handler ECD : %x\n", ecd);
if (sp > 0)
pm [sp+PSR_ECD] = ecd;
else
hlt = TRUE;
return;
}
void imsai_fif_out(BYTE data)
{
static int fdstate = 0; /* state of the fd */
static int fdaddr[16]; /* address of disk descriptors */
static int descno; /* descriptor # */
void disk_io(int);
/*
* The controller understands these commands:
* 0x10: set address of a disk descriptor from the following two out's
* 0x00: do the work as setup in the disk descriptor
* 0x20: reset a drive to home position, the lower digit contains
* the drive to reset, 0x2f for all drives
*
* The dd address only needs to be set once, the OS then can adjust
* the wanted I/O in the descriptor and send the 0x00 command
* multiple times for this descriptor.
*
* The commands 0x10 and 0x00 are OR'ed with a descriptor number
* 0x0 - 0xf, so there can be 16 different disk descriptors that
* need to be remembered.
*/
switch (fdstate) {
case 0: /* start of command phase */
switch (data & 0xf0) {
case 0x00: /* do what disk descriptor says */
descno = data & 0xf;
disk_io(fdaddr[descno]);
break;
case 0x10: /* next 2 is address of disk descriptor */
descno = data & 0xf;
fdstate++;
break;
case 0x20: /* reset drive(s) */
break; /* no mechanical drives, so nothing to do */
default:
printf("FIF: unknown cmd %02x\r\n", data);
return;
}
break;
case 1: /* LSB of disk descriptor address */
fdaddr[descno] = data;
fdstate++;
break;
case 2: /* MSB of disk descriptor address */
fdaddr[descno] += data << 8;
fdstate = 0;
break;
default:
printf("FIF: internal state error\r\n");
cpu_error = IOERROR;
cpu_state = STOPPED;
break;
}
}