INSERT[D0LANG];
NOMIDASINIT;
TITLE[d0rdtpc];
*last edited by CT June 10, 1979
SETTASK[17];

RV[REFR,77];	*memory refresh address

*The following registers hold the volatile state of the processor on a fault: 
RV[RXALU,76];	*ALU result and SALUF
RV[RXAPC,75];	*APCTask&APC
RV[RXCTASK,74];	*CTASK.NCIA
RV[RXPPB,73];	*Page,Parity,BootReason
RV[RXSTK,72];	*Stackpointer

RV[RTMP,71];	*temporary

*The following registers are used for D0-Midas communication (RTMP is also used):
RV[RWSTAT,70];	*status register
RV[RDATA,67];	*holds data

*FFault determines how faults will be treated when programs are running.  If it is
*zero, all faults will be reported to Midas.  If FFault is nonzero, the kernel will
*send control through location 120 when a fault occurs and PARITY # 0 (faults with
*PARITY = 0 are breakpoints).
RV[FFAULT,66];

*Registers between 360 and 367 are used by the Midas overlays.  The following 
*registers, used by WriteMI,  are also in this range.
RV[RADDR,65];

RV[RCNT,64];
RV[STACK4,64];

RV[RW0,63];
RV[STACK3,63];

RV[RW1,62];
RV[STACK2,62];

RV[STACK1,61];
MC[pStk1,361]; *pointer to stack1
RV[STACK0,60];


*Constants for Recv and Send
MC[RecvByte,12];
MC[RecvWord,16];
MC[SendByte,21];
MC[SendWord,25];

*The following are at fixed locations in Kernel.mc:
UserFault:	Return, AT[120];
NextCom:	Return, AT[7404];
Send:	Return, AT[7460];
Recv:	Return, AT[7464];

*d0rdtpc overlay
*Used by Midas to read TPC for any task.

*Notify task n to do the read
OverlayArea:
	RWSTAT ← RecvByte, Call[Recv], at[7500]; *get task number to read
	stack1 ← T, at[7501];
	T ← 7400c, at[7502];
	stack1 ← (lsh[stack1,14]) + (T), at[7503];
	stack1 ← (stack1) + (111c), at[7504]; *stack1 points to task n, location GetTPC (7511)
	RTMP ← pStk1,at[7505];
	Stkp ← RTMP, at[7506]; *set stkp to point to stack1
	stack0 ← 177400c, at[7507]; *set up stack0 to point to task 17, location 7515
	stack0 ← (stack0) + (115c), goto[NotifyBothWays], at[7510];

GetTPC:	usectask, at[7511];
	MNBR ← APC&APCTASK, at[7512];
NotifyBothWays:
	APC&APCTask ← Stack&-1,at[7513];
	return, AT[7514];
	T ← MNBR, AT[7515]; *back in task 17, get recovered TPC
	RDATA ← T, AT[7516];
	nop, AT[7517];
	RWSTAT ← SendWord, Call[Send], AT[7520]; *send the word to Midas
	goto[NextCom], AT[7521];

	END;