- have some emulation modes for single stepping, breaking, changing emulation speed

- started to make a better CPU state output with opcode mnemonics

8 files changed, 133 insertions, 17 deletions

diff --git a/README b/README
index da96843..29cf2cf 100644
--- a/README
+++ b/README
@@ -121,6 +121,9 @@ devices (ROM, RAM, VIA) to the bus
 29.11.2020
 work on 7-segment display in emulator
 
+5.12.2020
+work on emulator (disassembly and single-stepping)
+
 commands
 --------
 
diff --git a/emu/6502.c b/emu/6502.c
index 877f3f5..c52373f 100644
--- a/emu/6502.c
+++ b/emu/6502.c
@@ -150,10 +150,62 @@ static bool is_carry( cpu_6502_t *cpu )
 {
 	return cpu->PS & PS_C;
 }
+
+static const char mnemonic[NOF_OPCODES][MAX_MENMONIC_LENGTH] = {
+	/*         0     1      2      3      4      5      6      7      8      9      A      B      C      D      E      F */
+	/* 0 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 1 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 2 */  "JSR", "???", "???", "???", "???", "???", "???", "???", "???", "???", "ROL", "???", "???", "???", "???", "???",
+	/* 3 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 4 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "JMP", "???", "???", "???",
+	/* 5 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 6 */  "RTS", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 7 */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* 8 */  "???", "???", "???", "???", "???", "???", "STX", "???", "DEY", "???", "???", "???", "???", "???", "STX", "???",
+	/* 9 */  "BCC", "???", "???", "???", "???", "???", "???", "???", "???", "???", "TXS", "???", "???", "???", "???", "???",
+	/* A */  "LDY", "???", "LDX", "???", "LDY", "LDA", "LDX", "???", "???", "LDA", "???", "???", "???", "???", "???", "???",
+	/* B */  "BCS", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* C */  "???", "???", "???", "???", "???", "???", "???", "???", "INY", "???", "DEX", "???", "???", "???", "???", "???",
+	/* D */  "BNE", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???",
+	/* E */  "CPX", "???", "???", "???", "???", "???", "INC", "???", "???", "SBC", "NOP", "???", "???", "???", "???", "???",
+	/* F */  "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???", "???"
+
+/*
+             "BRK", "ORA", ""   , "", "TSB", "ORA", "ASL", "RMB0", "PHP", "ORA", "ASL", ""   , "TSB", "ORA", "ASL", "BBR0",
+             "BPL", "ORA", "ORA", "", "TRB", "ORA", "ASL", "RMB1", "CLC", "ORA", "INC", ""   , "TRB", "ORA", "ASL", "BBR1",
+             "JSR", "AND", ""   , "", "BIT", "AND", "ROL", "RMB2", "PLP", "AND", "ROL", ""   , "BIT", "AND", "ROL", "BBR2",
+             "BMI", "AND", "AND", "", "BIT", "AND", "ROL", "RMB3", "SEC", "AND", "DEC", ""   , "BIT", "AND", "ROL", "BBR3",
+             "RTI", "EOR", ""   , "", ""   , "EOR", "LSR", "RMB4", "PHA", "EOR", "LSR", ""   , "JMP", "EOR", "LSR", "BBR4",
+             "BVC", "EOR", "EOR", "", ""   , "EOR", "LSR", "RMB5", "CLI", "EOR", "PHY", ""   , ""   , "EOR", "LSR", "BBR5",
+             "RTS", "ADC", ""   , "", "STZ", "ADC", "ROR", "RMB6", "PLA", "ADC", "ROR", ""   , "JMP", "ADC", "ROR", "BBR6",
+             "BVS", "ADC", "ADC", "", "STZ", "ADC", "ROR", "RMB7", "SEI", "ADC", "PLY", ""   , "JMP", "ADC", "ROR", "BBR7",
+             "BRA", "STA", ""   , "", "STY", "STA", "STX", "SMB0", "DEY", "BIT", "TXA", ""   , "STY", "STA", "STX", "BBS0",
+             "BCC", "STA", "STA", "", "STY", "STA", "STX", "SMB1", "TYA", "STA", "TXS", ""   , "STZ", "STA", "STZ", "BBS1",
+             "LDY", "LDA", "LDX", "", "LDY", "LDA", "LDX", "SMB2", "TAY", "LDA", "TAX", ""   , "LDY", "LDA", "LDX", "BBS2",
+             "BCS", "LDA", "LDA", "", "LDY", "LDA", "LDX", "SMB3", "CLV", "LDA", "TSX", ""   , "LDY", "LDA", "LDX", "BBS3",
+             "CPY", "CMP", ""   , "", "CPY", "CMP", "DEC", "SMB4", "INY", "CMP", "DEX", "WAI", "CPY", "CMP", "DEC", "BBS4",
+             "BNE", "CMP", "CMP", "", ""   , "CMP", "DEC", "SMB5", "CLD", "CMP", "PHX", "STP", ""   , "CMP", "DEC", "BBS5",
+             "CPX", "SBC", ""   , "", "CPX", "SBC", "INC", "SMB6", "INX", "SBC", "NOP", ""   , "CPX", "SBC", "INC", "BBS6",
+             "BEQ", "SBC", "SBC", "", ""   , "SBC", "INC", "SMB7", "SED", "SBC", "PLX", ""   , ""   , "SBC", "INC", "BBS7"	
+*/
+};
+
+void cpu_6502_get_opcode_mnemonic( cpu_6502_t *cpu, char *buf, int buflen, uint16_t addr )
+{
+	uint8_t opcode;
+	
+	opcode = cpu_6502_read_byte( cpu, addr );
 	
-void cpu_6502_print_state( cpu_6502_t *cpu, uint8_t opcode )
+	snprintf( buf, buflen, "%s (%02X)", mnemonic[opcode], opcode );
+}
+	
+void cpu_6502_print_state( cpu_6502_t *cpu, uint16_t addr )
 {
-	fprintf( stderr, "PC: %04X SP: 01%02X PS: %02X %c%c-%c%c%c%c%c A: %02X X: %02X Y: %02X OP: %02X steps: %d\n", 
+	char opcode_str[MAX_OPCODE_MNEMONIC_STRING_LENGTH];
+	
+	cpu_6502_get_opcode_mnemonic( cpu, opcode_str, MAX_OPCODE_MNEMONIC_STRING_LENGTH, addr );
+	
+	fprintf( stderr, "PC: %04X SP: 01%02X PS: %02X %c%c-%c%c%c%c%c A: %02X X: %02X Y: %02X steps: %d OP: %s\n", 
 		cpu->PC, cpu->SP, cpu->PS,
 		is_negative( cpu ) ? 'N' : 'n',
 		is_overflow( cpu ) ? 'V' : 'v',
@@ -162,7 +214,8 @@ void cpu_6502_print_state( cpu_6502_t *cpu, uint8_t opcode )
 		is_interrupt( cpu ) ? 'I' : 'i',
 		is_zero( cpu ) ? 'Z' : 'z',
 		is_carry( cpu ) ? 'C' : 'c',
-		cpu->A, cpu->X, cpu->Y, opcode, cpu->steps );
+		cpu->A, cpu->X, cpu->Y, cpu->steps,
+		opcode_str );
 }
 
 static void update_negative_and_sign( cpu_6502_t *cpu, uint8_t x )
@@ -200,7 +253,7 @@ void cpu_6502_step( cpu_6502_t *cpu )
 	cpu->PC++;
 
 	if( cpu->debug_flags & DEBUG_STATUS ) {
-		cpu_6502_print_state( cpu, opcode );
+		cpu_6502_print_state( cpu, cpu->PC-1 );
 	}
 	if( cpu->debug_flags & DEBUG_STACK ) {
 		cpu_6502_print_stack( cpu );
@@ -279,7 +332,7 @@ void cpu_6502_step( cpu_6502_t *cpu )
 			update_negative_and_sign( cpu, cpu->Y );
 			break;
 		
-		case INC_IMPL:
+		case INC_ZERO:
 			operand8 = cpu_6502_read_byte( cpu, cpu->PC );
 			cpu->PC++;
 			tmp = cpu_6502_read_byte( cpu, operand8 );
diff --git a/emu/6502.h b/emu/6502.h
index bfc8314..1880c90 100644
--- a/emu/6502.h
+++ b/emu/6502.h
@@ -53,7 +53,7 @@ enum {
 	DEX_IMPL = 0xCA,
 	DEY_IMPL = 0x88,
 	INY_IMPL = 0xC8,
-	INC_IMPL = 0xE6,
+	INC_ZERO = 0xE6,
 	ROL_ACC  = 0x2A,
 	BNE_REL  = 0xD0,
 	BCC_REL  = 0x90,
@@ -67,6 +67,12 @@ enum {
 	NOP_IMPL = 0xEA
 };
 
+enum {
+	MAX_OPCODE_MNEMONIC_STRING_LENGTH = 20,
+	MAX_MENMONIC_LENGTH = 5,
+	NOF_OPCODES = 256
+};
+
 void cpu_6502_init( cpu_6502_t *cpu, bus_t *bus, bool initialize );
 void cpu_6502_reset( cpu_6502_t *cpu );
 uint8_t cpu_6502_read_byte( cpu_6502_t *cpu, uint16_t addr );
@@ -78,7 +84,8 @@ uint8_t cpu_6502_pop_byte( cpu_6502_t *cpu );
 uint16_t cpu_6502_pop_word( cpu_6502_t *cpu );
 void cpu_6502_run( cpu_6502_t *cpu, int steps );
 void cpu_6502_step( cpu_6502_t *cpu );
-void cpu_6502_print_state( cpu_6502_t *cpu, uint8_t opcode );
+void cpu_6502_get_opcode_mnemonic( cpu_6502_t *cpu, char *buf, int buflen, uint16_t addr );
+void cpu_6502_print_state( cpu_6502_t *cpu, uint16_t addr );
 void cpu_6502_print_memory( cpu_6502_t *cpu, uint16_t base, uint8_t size );
 void cpu_6502_print_stack( cpu_6502_t *cpu );
 void cpu_6502_print_zerop_page( cpu_6502_t *cpu );
diff --git a/emu/emu.c b/emu/emu.c
index 539c89b..421d4cc 100644
--- a/emu/emu.c
+++ b/emu/emu.c
@@ -73,6 +73,10 @@ int main( int argc, char *argv[] )
 	if( args_info.debug_given ) {
 		emul.debug = true;
 	}
+	if( args_info.start_paused_given ) {
+		emul.paused = true;
+		emul.speed = 25;
+	}
 	emul_start( &emul );
 
 	cpu_6502_reset( &cpu );
diff --git a/emu/emul.c b/emu/emul.c
index bf64d13..0399d33 100644
--- a/emu/emul.c
+++ b/emu/emul.c
@@ -11,6 +11,8 @@ void emul_init( emul_t *emul, cpu_6502_t *cpu, bus_t *bus, int width, int height
 	emul->width = width;
 	emul->height = height;
 	emul->debug = false;
+	emul->paused = false;
+	emul->speed = CPU_FREQUENCY;
 }
 
 void emul_start( emul_t *emul )
@@ -78,31 +80,68 @@ void emul_run( emul_t *emul, int nof_steps )
 	if( emul->gui ) {
 		SDL_Event event;
 		bool done = false;
+
+		if( emul->paused ) {
+			fprintf( stderr, "CPU is paused, press\n"
+				"(s) for single step\n"
+				"(c) for continue running\n"
+				"(b) break to single stepping\n"
+				"(+) speed up\n"
+				"(-) speed down\n"
+				"(q) or (ESC) for shutting down\n" );
+		}
+
 		while( !done ) {
 			uint32_t frame_start = SDL_GetTicks( );
-			
+						
 			SDL_PollEvent( &event );
 			
 			switch( event.type ) {
 				case SDL_KEYDOWN:
 					switch( event.key.keysym.sym ) {
 						case SDLK_ESCAPE:
+						case SDLK_q:
 							done = true;
 							break;
+						case SDLK_c:
+							fprintf( stderr, "continuing at normal speed %1.6f MHz\n", ( (double)emul->speed / 1000000 ) );
+							emul->paused = false;
+							break;
+						case SDLK_b:
+							fprintf( stderr, "CPU paused (in single step mode)\n" );
+							emul->paused = true;
+							break;
+						case SDLK_s:
+							cpu_6502_run( emul->cpu, 1 );
+							break;
+						case SDLK_PLUS:
+						case SDLK_KP_PLUS:
+							emul->speed *= 10;
+							if( emul->speed > CPU_FREQUENCY ) {
+								emul->speed = CPU_FREQUENCY;
+							}
+							fprintf( stderr, "CPU speed  is %1.6f MHz now\n", ( (double)emul->speed / 1000000 ) );
+							break;
+						case SDLK_MINUS:
+						case SDLK_KP_MINUS:
+							emul->speed /= 10;
+							if( emul->speed < 25 ) {
+								emul->speed = 25;
+							}
+							fprintf( stderr, "CPU speed  is %1.6f MHz now\n", ( (double)emul->speed / 1000000 ) );
+							break;
 					}
 					break;
-
+				
 				case SDL_QUIT:
 					done = true;
-					break;
+					break;				
 			}
 			
-			cpu_6502_run( emul->cpu, CPU_FREQUENCY / DISPLAY_FPS );
-			
-			if( emul->debug ) {
-				cpu_6502_print_state( emul->cpu, 0 );
+			if( !emul->paused ) {
+				cpu_6502_run( emul->cpu, emul->speed / DISPLAY_FPS );
 			}
-			
+						
 			SDL_RenderCopy( emul->renderer, emul->background_texture, NULL, NULL );
 
 			for( int i = 0; i < emul->bus->nof_devices; i++ ) {
diff --git a/emu/emul.h b/emu/emul.h
index a0e6b5f..fa443a0 100644
--- a/emu/emul.h
+++ b/emu/emul.h
@@ -34,6 +34,8 @@ typedef struct emul_t {
 	int width;
 	int height;
 	bool debug;
+	bool paused;
+	int speed;
 #ifdef WITH_GUI
 	SDL_Window *window;
 	SDL_Renderer *renderer;
diff --git a/emu/options.ggo b/emu/options.ggo
index 5a93897..90bb5c1 100644
--- a/emu/options.ggo
+++ b/emu/options.ggo
@@ -51,7 +51,7 @@ section "Debug Options"
 	option "print-7seg" -
 		"Print what the 7-segment display on the VIA is doing"
 		optional
-		
+			
 section "GUI Options"
 			
 	option "width" -
@@ -65,3 +65,7 @@ section "GUI Options"
 		int typestr="pixel"
 		default="250"
 		optional
+
+	option "start-paused" -
+		"Start the CPU in paused mode"
+		optional
diff --git a/emu/options.ggo.in b/emu/options.ggo.in
index 9e54009..ccec63e 100644
--- a/emu/options.ggo.in
+++ b/emu/options.ggo.in
@@ -51,7 +51,7 @@ section "Debug Options"
 	option "print-7seg" -
 		"Print what the 7-segment display on the VIA is doing"
 		optional
-		
+			
 section "GUI Options"
 			
 	option "width" -
@@ -65,3 +65,7 @@ section "GUI Options"
 		int typestr="pixel"
 		default="250"
 		optional
+
+	option "start-paused" -
+		"Start the CPU in paused mode"
+		optional