From 80b6848108db41fe263ecd4c46b190f8c8d9faf8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rados=C5=82aw=20Kujawa?= <radoslaw.kujawa@c0ff33.net>
Date: Thu, 26 Jan 2017 13:11:00 +0100
Subject: [PATCH] Preliminary support for stepping.

---
 src/rk65c02.c | 53 +++++++++++++++++++++++++++++++++++----------------
 src/rk65c02.h |  4 +++-
 2 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/src/rk65c02.c b/src/rk65c02.c
index b2b59d7..1abea0c 100644
--- a/src/rk65c02.c
+++ b/src/rk65c02.c
@@ -10,6 +10,8 @@
 #include "instruction.h"
 #include "rk65c02.h"
 
+void rk65c02_exec(rk65c02emu_t *);
+
 rk65c02emu_t
 rk65c02_init(bus_t *b)
 {
@@ -23,30 +25,49 @@ rk65c02_init(bus_t *b)
 }
 
 void
-rk65c02_start(rk65c02emu_t *e) {
+rk65c02_exec(rk65c02emu_t *e)
+{
 	instruction_t i;
 	instrdef_t id;
 
+	/* XXX: handle breakpoints and watch points */
+
+	/* if disassembly-when-running enabled */
+	disassemble(e->bus, e->regs.PC);
+
+	i = instruction_fetch(e->bus, e->regs.PC);
+	id = instruction_decode(i.opcode);
+
+	if (id.emul != NULL) {
+		id.emul(e, &id, &i);
+		/* if (!instruction_modify_pc) */
+		program_counter_increment(e, &id);
+	} else {
+		printf("unimplemented opcode %X @ %X\n", i.opcode,
+		    e->regs.PC);
+		e->state = STOPPED;
+		e->stopreason = EMUERROR;
+	}
+}
+
+void
+rk65c02_start(rk65c02emu_t *e) {
+
 	e->state = RUNNING;
 	while (e->state == RUNNING) {
-		/* XXX: handle breakpoints and watch points */
+		rk65c02_exec(e);
+	}
+}
 
-		/* if disassembly-when-running enabled */
-		disassemble(e->bus, e->regs.PC);
+void
+rk65c02_step(rk65c02emu_t *e, uint16_t steps) {
 
-		i = instruction_fetch(e->bus, e->regs.PC);
-		id = instruction_decode(i.opcode);
+	uint16_t i = 0;
 
-		if (id.emul != NULL) {
-			id.emul(e, &id, &i);
-			/* if (!instruction_modify_pc) */
-			program_counter_increment(e, &id);
-		} else {
-			printf("unimplemented opcode %X @ %X\n", i.opcode,
-			    e->regs.PC);
-			e->state = STOPPED;
-			e->stopreason = EMUERROR;
-		}
+	e->state = STEPPING;
+	while ((e->state == STEPPING) && (i < steps)) {
+		rk65c02_exec(e);
+		i++;
 	}
 }
 /*
diff --git a/src/rk65c02.h b/src/rk65c02.h
index a21128e..4349fc7 100644
--- a/src/rk65c02.h
+++ b/src/rk65c02.h
@@ -9,10 +9,11 @@ typedef enum {
 	STEPPING	/* XXX: how to implement? */
 } emu_state_t;
 
-typedef enum
+typedef enum {
 	STP,		/* due to 65C02 STP instruction */
 	BREAKPOINT,	/* due to breakpoint set */
 	WATCHPOINT,	/* due to watchpoint set */
+	STEPPED,	/* stepped appropriate number of instructions */
 	HOST,		/* due to host stop function called */
 	EMUERROR	/* due to emulator error */
 } emu_stop_reason_t;
@@ -56,6 +57,7 @@ typedef struct rk65c02emu rk65c02emu_t;
 
 rk65c02emu_t rk65c02_init(bus_t *);
 void rk65c02_start(rk65c02emu_t *);
+void rk65c02_step(rk65c02emu_t *, uint16_t);
 
 #endif