From d7a92f4441ebed18ebeb9fc71205493df20930f2 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Mon, 18 Mar 2019 17:06:14 -0400
Subject: [PATCH] cop/brk debugger support... cop=1 brk=1

to enable brk/cop support.  cop/brk instructions will be caught *BEFORE* execution and drop into the debugger shell.  step/go/next will execute the instruction as normal.  %pc++ will skip over the instruction.
---
 src/debug_shell.re2c | 36 +++++++++++++++++++++++++++++++++++-
 src/defcomm.h        |  4 ++++
 src/instable.h       | 18 ++++++++++++++----
 src/sim65816.c       |  4 +++-
 4 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/src/debug_shell.re2c b/src/debug_shell.re2c
index 368528b..5003e08 100644
--- a/src/debug_shell.re2c
+++ b/src/debug_shell.re2c
@@ -885,6 +885,36 @@ next:
 	return 0;
 }
 
+static int do_brk_cop(const char *cp, int which) {
+	/* brk=1 / brk=0 */
+
+	const char *YYCURSOR = cp;
+	int value = 0;
+
+	/*!re2c
+		[01] eol {
+			value = *cp - '0';
+			goto next;
+		}
+		* { return -1; }
+	*/
+next:
+
+	switch(which) {
+		case 0x00:
+			engine.flags &= ~FLAG_WANT_BRK;
+			if (value) engine.flags |= FLAG_WANT_BRK;
+			printf("brk intercept %s\n\n", value ? "on" : "off");
+			break;
+		case 0x02:
+			engine.flags &= ~FLAG_WANT_COP;
+			if (value) engine.flags |= FLAG_WANT_COP;
+			printf("cop intercept %s\n\n", value ? "on" : "off");
+			break;
+	}
+	return 0;
+}
+
 static word32 do_mem_assign(word32 addr, const char *cp) {
 	/* "string" -> pokes ASCII chars */
 	/* 'string' -> pokes ASCII chars | 0x80 */
@@ -1122,6 +1152,8 @@ static int parse_command(const char *cp) {
 		("q" | "quit" | "exit" | "bye") eol { return 'q'; }
 		"reset" eol { do_reset(); return 0; }
 		("help" | "?") eol { do_help(); return 0; }
+		"brk=" { return do_brk_cop(YYCURSOR, 0x00); }
+		"cop=" { return do_brk_cop(YYCURSOR, 0x02); }
 
 		// register stuff
 
@@ -1420,7 +1452,9 @@ int debug_shell(int code) {
 		} 
 		printf("%06x: %0*x\n", g_abort_address, g_abort_bytes * 2, g_abort_value);
 	}
-	if (code == RET_BRK) {
+	if (code == RET_BRK || code == RET_COP) {
+		/* todo -- should do this at end, verify pc/memory unchanged */
+		engine.flags |= FLAG_IGNORE_BRK;
 		/* hit a BRK op */
 	}
 	if (code == RET_HALT) {
diff --git a/src/defcomm.h b/src/defcomm.h
index aaca6c0..849b322 100644
--- a/src/defcomm.h
+++ b/src/defcomm.h
@@ -100,6 +100,10 @@
 #define FLAG_IGNORE_BP	0x02
 #define FLAG_STEP		0x04
 #define FLAG_WANT_BRK	0x08
+#define FLAG_WANT_COP	0x10
+#define FLAG_WANT_RET	0x20
+#define FLAG_WANT_JSL	0x40
+#define FLAG_IGNORE_BRK	0x80 /* and cop */
 
 #define MODE_BORDER		0
 #define MODE_TEXT		1
diff --git a/src/instable.h b/src/instable.h
index bb71684..21b3c48 100644
--- a/src/instable.h
+++ b/src/instable.h
@@ -76,9 +76,11 @@ brk_testing_SYM
 #else
 	GET_1BYTE_ARG;
 
-	if(flags & FLAG_WANT_BRK) {
-		CYCLES_PLUS_2;
-		FINISH(RET_BRK, arg);
+	if (flags & FLAG_WANT_BRK) {
+		if (~flags & FLAG_IGNORE_BRK) {
+			CYCLES_PLUS_2;
+			FINISH(RET_BRK, arg);
+		}
 	}
 	INC_KPC_2;
 	g_num_brk++;
@@ -167,8 +169,16 @@ cop_native_SYM
 
 
 #else
-	g_num_cop++;
+	GET_1BYTE_ARG;
+
+	if (flags & FLAG_WANT_COP) {
+		if (~flags & FLAG_IGNORE_BRK) {
+			CYCLES_PLUS_2;
+			FINISH(RET_COP, arg);
+		}
+	}
 	INC_KPC_2;
+	g_num_cop++;
 
 	psr = psr & (~0x82);
 	psr |= (neg << 7);
diff --git a/src/sim65816.c b/src/sim65816.c
index 43ba00f..1bfc7a2 100644
--- a/src/sim65816.c
+++ b/src/sim65816.c
@@ -1607,7 +1607,9 @@ int run_prog()      {
 
     if (ret == RET_MP) break;
     if (ret == RET_BP) break;
-    engine.flags &= ~(FLAG_IGNORE_BP | FLAG_IGNORE_MP);
+    if (ret == RET_BRK) break;
+    if (ret == RET_COP) break;
+    engine.flags &= ~(FLAG_IGNORE_BP | FLAG_IGNORE_MP | FLAG_IGNORE_BRK);
     if(g_stepping) {
       ret = 0;
       break;