fixed div bug

added chaosnet support

Makefile

@@ -3,7 +3,7 @@
 # $Id$
 #
 
-USIM_SRC = main.c decode.c ucode.c disk.c iob.c syms.c config.c sdl.c
+USIM_SRC = main.c decode.c ucode.c disk.c iob.c chaos.c syms.c config.c sdl.c
 USIM_HDR = ucode.h config.h
 
 USIM_LIBS = -lSDL -lpthread

README

@@ -1,5 +1,5 @@
 CADR simulator
-10/19/04
+10/21/04
 Brad Parker
 [email protected]
 
@@ -61,18 +61,18 @@ There are some hacks for noticing unibus access but no xbus/unibus
 mapping support.  The two machine lash-up/debug interface is not (yet)
 supported.  I want to add this, however.
 
-I believe the divide code is still broken and needs to be fixed.  I
-put in a hack which aborts the last step and now it seems ok, but I
-think something is wrong with my emulation of the h/w.
+I finally fixed the divide code.  Naturally the Q shift and the ALU
+shift (with a bit conditional on the Q sign) happen at the same time
+in the hardware (but not in the C code :-).
 
 There's a long delay when booting, even though the world is running
 and system-x works fine.  I need to track this down - possibly waiting
-for a time packet?
+for a time packet?  The system is available right away, however, try
+"F2-p".
 
 What needs to be done?
 ----------------------
 
-- fix the divide code
 - cleanup keyboard emulation
 - cleanup mouse emulation
 - cleanup chaosnet emulation

div.c

@@ -1,82 +1,150 @@
+/*
+;;; DIVIDE SUBROUTINE
+;   DIVIDEND IN M-1, DIVISOR IN M-2
+;   QUOTIENT IN Q-R, REMAINDER IN M-1, CLOBBERS A-TEM1
+
+DIV	(JUMP-GREATER-OR-EQUAL-XCT-NEXT M-1 A-ZERO DIV1)
+       ((A-TEM1 Q-R) M-1)	;Q GETS MAGNITUDE OF DIVIDEND, A-TEM1 SAVES ORIGINAL
+	((Q-R) SUB M-ZERO A-TEM1)
+DIV1	((M-1) DIVIDE-FIRST-STEP M-ZERO A-2)
+DIV1A	(CALL-IF-BIT-SET (BYTE-FIELD 1 0) Q-R TRAP)	;DIVIDE OVERFLOW
+
+(REPEAT 31. ((M-1) DIVIDE-STEP M-1 A-2))
+
+	((M-1) DIVIDE-LAST-STEP M-1 A-2)
+	(JUMP-LESS-OR-EQUAL-XCT-NEXT M-ZERO A-TEM1 DIV2) ;JUMP IF POSITIVE DIVIDEND
+       ((M-1) DIVIDE-REMAINDER-CORRECTION-STEP M-1 A-2) ;M-1 GETS MAGNITUDE OF REMAINDER
+	((M-1) SUB M-ZERO A-1)		;NEGATIVE DIVIDEND => NEGATIVE REMAINDER
+DIV2	((A-TEM1) XOR M-2 A-TEM1)	;IF SIGNS OF DIVIDEND AND DIVISOR ARE DIFFERENT,
+	(POPJ-LESS-OR-EQUAL M-ZERO A-TEM1)
+	(POPJ-AFTER-NEXT
+	 (A-TEM1) Q-R)
+       ((Q-R) SUB M-ZERO A-TEM1)	;THEN QUOTIENT IS NEGATIVE
+*/
+
 /*
  * unsigned divide simulation; based on CADR h/w & microcode
  */
 
+int show = 1;
+
 void ud(unsigned int dividend,
 		     unsigned int divisor,
 		     unsigned int *pquotient,
 		     unsigned int *premainder )
 {
-	int q, m, a, alu;
+	unsigned int q, m, a, alu, old_q;
 	int i;
 	int do_sub, do_add;
+	int negq, nega;
 
 	q = dividend;
 	a = divisor;
 	m = 0;
+	negq = 0;
+	nega = 0;
+
+	printf("(/ 0x%x (%o) 0x%x (%o) ); ", q, q, a, a);
+
+	if ((int)q < 0) {
+		q = -(int)q;
+		negq = 1;
+	}
+
+	if ((int)a < 0) {
+		nega = 1;
+	}
+
+	if (show) printf("\n");
 
 	alu = m - a;
 
+old_q = q;
 	q <<= 1;
 	if ((alu & 0x80000000) == 0)
 		q |= 1;
-	m = (alu << 1) | ((q & 0x80000000) ? 1 : 0);
+//	m = (alu << 1) | ((q & 0x80000000) ? 1 : 0);
+	m = (alu << 1) | ((old_q & 0x80000000) ? 1 : 0);
 
 	for (i = 0; i < 32; i++) {
 
 		do_sub = q & 1;
-		if (0)
-		printf("loop %d, m %08x alu %08x, q %08x, do_sub %d\n",
-		       i, m, alu, q, do_sub);
+
+		if (show)
+		printf("loop %d, m %08x (%o) alu %08x (%o), q %08x (%o), do_sub %d\n",
+		       i, m, m, alu, alu, q, q, do_sub);
 
 		if (do_sub) {
 			alu = m - a;
 		} else {
 			alu = m + a;
 		}
 
+old_q = q;
 		q <<= 1;
 		if ((alu & 0x80000000) == 0)
 			q |= 1;
 
 		if (i < 31)
-			m = (alu << 1) | ((q & 0x80000000) ? 1 : 0);
+//			m = (alu << 1) | ((q & 0x80000000) ? 1 : 0);
+			m = (alu << 1) | ((old_q & 0x80000000) ? 1 : 0);
 		else
 			m = alu;
 	}
 
 	do_sub = q & 1;
-	if (0)
-	printf("remainder; alu %08x, q %08x, do_sub %d\n", alu, q, do_sub);
+
+	if (nega)
+		do_sub = !do_sub;
+
+	if (show)
+	printf("remainder; m %08x, alu %08x, q %08x, do_sub %d\n", m, alu, q, do_sub);
 
 	if (do_sub) {
-//		alu = alu;
-		alu = m;
+		/* setm */
+		printf("setm; ");
 	} else {
-//		alu = alu + a;
 		alu = m + a;
 	}
 
-//	alu >>= 1;
-//	q >>= 1;
+	if (negq ^ nega) {
+		printf("diff; ");
+		q = -(int)q;
+	}
 
-	printf("done; alu %08x, q %08x (%d,%o)\n", alu, q, q, q);
+	printf("done; alu %08x (%o), q %08x (%o) (%d,%d)\n", alu, alu, q, q, alu, q);
 }
 
 
 main()
 {
 	unsigned int q, r;
 
-//	unsigned_divide(0, 3, &q, &r);
-//	unsigned_divide(4, 2, &q, &r);
-//	ud(4, 2, &q, &r);
+	show = 0;
+	ud(4, 2, &q, &r);
+#if 1
+	ud(10, 3, &q, &r);
+
 	ud(8, 2, &q, &r);
-//	ud(10, 5, &q, &r);
-//	ud(10, 3, &q, &r);
-	ud(100, 3, &q, &r);
-//	ud(021, 0503, &q, &r);
-//	ud(0136, 021, &q, &r);
+
+	ud(10, 5, &q, &r);
+
+//	ud(100, 3, &q, &r);
+
+//	ud(0503, 021, &q, &r);
+	ud(06434, 0503, &q, &r);
+	ud(0136, 021, &q, &r);
+
+	ud(0142, 021, &q, &r);
+
+	ud(0x7fffffff, 02, &q, &r);
+	ud(-1, 2, &q, &r);
+
+	ud(-6, 2, &q, &r);
+//	show=1;
+	ud(-6, -2, &q, &r);
+	ud(6, 2, &q, &r);
+#endif
 
 #if 0
 	int i;