Merge pull request #2 from Russell-S-Harper/master

Synchronizing.
2024-06-14 21:29:36 +00:00 · 2018-08-06 22:17:00 -04:00 · 2018-08-06 22:17:00 -04:00 · e887a83539
commit e887a83539
parent a1f07b12ab f3f8cd5aa3
16 changed files with 2225 additions and 0 deletions
--- a/common-post-process/Makefile
+++ b/common-post-process/Makefile
@ -0,0 +1,10 @@
+TGT=common-post-process
+
+$(TGT): main.c $(TGT).h $(TGT).re $(TGT).l $(TGT).y
+	re2c -is $(TGT).re -o $(TGT).c
+	flex --header-file=$(TGT).yy.h -o $(TGT).yy.c $(TGT).l
+	bison -d $(TGT).y
+	gcc main.c $(TGT).c $(TGT).tab.c $(TGT).yy.c -lfl -lm -o $(TGT)
+
+clean: 
+	rm -f $(TGT).c $(TGT).yy.h $(TGT).yy.c $(TGT).tab.h $(TGT).tab.c
--- a/common-post-process/common-post-process.h
+++ b/common-post-process/common-post-process.h
@ -0,0 +1,71 @@
+#ifndef __COMMON_POST_PROCESS_H
+#define __COMMON_POST_PROCESS_H
+
+/* How many bits for ... */
+
+/* ... internal significands */
+#define INT_SIGN	48
+
+/* ... internal fractions */
+#define INT_FRAC	16
+
+/* ... internal full numbers */
+#define INT_FULL	(INT_SIGN + INT_FRAC)
+
+/* ... exported significands */
+#define EXP_SIGN	20
+
+/* ... exported fractions */
+#define EXP_FRAC	10
+
+/* ... exported full numbers */
+#define EXP_FULL	(EXP_SIGN + EXP_FRAC)
+
+/*
+	Internal calculations may require left shifting of
+	numbers by INT_FRAC bits, so be aware that the higher
+	bits of numbers may be lost if multiplying or dividing
+	large numbers.
+
+	These are the safe upper limits for various internal
+	significand and fraction combinations in bits.
+
+	+----------+----------+-------------+
+	| INT_SIGN | INT_FRAC | Upper Limit |
+	+----------+----------+-------------+
+	|    64    |     0    |   2^63-1    |
+	|    56    |     8    |   2^47-1    |
+	|    48    |    16    |   2^31-1    |
+	|    40    |    24    |   2^15-1    |
+	+----------+----------+-------------+
+*/
+
+/* Definitions for flex and bison */
+
+#ifndef TOKEN_LEN
+#define TOKEN_LEN	256
+#endif /* TOKEN_LEN */
+#define TOKENS		128
+#define IO_BUFFER	(TOKENS * TOKEN_LEN)	
+
+typedef enum
+{
+	TT_COMMAND, TT_DEFAULT, TT_WHITE_SPACE, TT_END_OF_LINE
+} TOKEN_TYPE;
+
+typedef struct
+{
+	TOKEN_TYPE type;
+	char text[TOKEN_LEN];
+} TOKEN;
+
+extern long long result;
+
+int yyparse (void);
+void yyerror(char const *s);
+
+int tokenizeInput(const char *cursor, TOKEN *tokens);
+long long parseCommon(const char *input);
+long long shiftCommon(long long base, long long amount);
+
+#endif /* __COMMON_POST_PROCESS_H */
--- a/common-post-process/common-post-process.l
+++ b/common-post-process/common-post-process.l
@ -0,0 +1,34 @@
+%{
+
+#include <stdio.h>
+#include <string.h>
+
+#include "common-post-process.tab.h"
+
+%}
+
+DEC	[0-9]+(\.[0-9]+)?
+HEX	\$[0-9A-Fa-f]+(\.[0-9A-Fa-f]+)?
+OCT	&[0-7]+(\.[0-7]+)?
+BIN	%[01]+(\.[01]+)?
+
+%%
+
+[A-Za-z_][A-Za-z0-9_]*	{ strncpy(yylval.sval, yytext, sizeof(yylval.sval)); return IDENTIFIER; }
+{DEC}|{HEX}|{OCT}|{BIN}	{ strncpy(yylval.sval, yytext, sizeof(yylval.sval)); return CONSTANT; }
+"<<"			return LEFT_OP;
+">>"			return RIGHT_OP;
+(<=)|(=<)		return LE_OP;
+(>=)|(=>)		return GE_OP;
+(<>)|(><)		return NE_OP;
+"&&"			return AND_OP;
+"||"			return OR_OP;
+[ \t\n]+        	; /* Ignore whitespace */
+[-()<>+~!*/%=&^|]	return yytext[0];
+.			{ fprintf(stderr, "SET (invalid character '%s')\n", yytext); exit(1); }
+
+%%
+
+int yywrap(void) {
+    return 1;
+}
--- a/common-post-process/common-post-process.re
+++ b/common-post-process/common-post-process.re
@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "common-post-process.h"
+
+static int copyToken(TOKEN *tokens, int index, TOKEN_TYPE type, const char *text, int length);
+
+int tokenizeInput(const char *cursor, TOKEN *tokens)
+{
+	const char *marker, *token;
+	int i;
+
+	for (i = 0; *cursor && i < TOKENS; )
+	{
+		token = cursor;
+/*!re2c
+		re2c:define:YYCTYPE = "char";
+		re2c:define:YYCURSOR = cursor;
+		re2c:define:YYMARKER = marker;
+		re2c:variable:yych = c;
+		re2c:indent:top = 2;
+		re2c:yyfill:enable = 0;
+		re2c:yych:conversion = 1;
+	
+		BELL						= "\x07" ;
+		BACKSPACE					= "\x08" ;
+		HORIZONTAL_TAB					= "\x09" ;
+		LINE_FEED					= "\x0a" ;
+		VERTICAL_TAB					= "\x0b" ;
+		FORM_FEED					= "\x0c" ;
+		CARRIAGE_RETURN					= "\x0d" ;
+		ESCAPE						= "\x1b" ;
+		DELETE						= "\x7f" ;
+	
+		SPACE						= "\x20" ;
+		EXCLAMATION_MARK				= "\x21" ;
+		QUOTATION_MARK					= "\x22" ;
+		NUMBER_SIGN					= "\x23" ;
+		DOLLAR_SIGN					= "\x24" ;
+		PERCENT_SIGN					= "\x25" ;
+		AMPERSAND					= "\x26" ;
+		APOSTROPHE					= "\x27" ;
+		LEFT_PARENTHESIS				= "\x28" ;
+		RIGHT_PARENTHESIS				= "\x29" ;
+		ASTERISK					= "\x2a" ;
+		PLUS_SIGN					= "\x2b" ;
+		COMMA						= "\x2c" ;
+		HYPHEN_MINUS					= "\x2d" ;
+		FULL_STOP					= "\x2e" ;
+		SOLIDUS						= "\x2f" ;
+		COLON						= "\x3a" ;
+		SEMICOLON					= "\x3b" ;
+		LESS_THAN_SIGN					= "\x3c" ;
+		EQUALS_SIGN					= "\x3d" ;
+		GREATER_THAN_SIGN				= "\x3e" ;
+		QUESTION_MARK					= "\x3f" ;
+		COMMERCIAL_AT					= "\x40" ;
+		LEFT_SQUARE_BRACKET				= "\x5b" ;
+		REVERSE_SOLIDUS					= "\x5c" ;
+		RIGHT_SQUARE_BRACKET				= "\x5d" ;
+		CIRCUMFLEX_ACCENT				= "\x5e" ;
+		LOW_LINE					= "\x5f" ;
+		GRAVE_ACCENT					= "\x60" ;
+		LEFT_CURLY_BRACKET				= "\x7b" ;
+		VERTICAL_LINE					= "\x7c" ;
+		RIGHT_CURLY_BRACKET				= "\x7d" ;
+		TILDE						= "\x7e" ;
+	
+		DIGIT		= [0-9] ;
+	
+		LETTER		= [A-Za-z] ;
+	
+		WHITE_SPACE	= BELL | BACKSPACE | HORIZONTAL_TAB | ESCAPE | DELETE | SPACE ;
+	
+		VALID		= DIGIT | LETTER | EXCLAMATION_MARK | DOLLAR_SIGN | PERCENT_SIGN | AMPERSAND
+					| LEFT_PARENTHESIS | RIGHT_PARENTHESIS | ASTERISK | PLUS_SIGN | HYPHEN_MINUS
+					| FULL_STOP | SOLIDUS | LESS_THAN_SIGN | EQUALS_SIGN | GREATER_THAN_SIGN
+					| LOW_LINE | VERTICAL_LINE | TILDE | WHITE_SPACE ;
+	
+		COMMAND		= LOW_LINE [Ss][Ee][Tt] LOW_LINE [Vv] WHITE_SPACE* LEFT_PARENTHESIS WHITE_SPACE* QUOTATION_MARK VALID+ QUOTATION_MARK WHITE_SPACE* RIGHT_PARENTHESIS ;
+	
+		DEFAULT		= . ;
+	
+		END_OF_LINE	= ( LINE_FEED | VERTICAL_TAB | FORM_FEED | CARRIAGE_RETURN )+ ;
+	
+		COMMAND		{ i = copyToken(tokens, i, TT_COMMAND, token, (int)(cursor - token)); continue; }
+		DEFAULT		{ i = copyToken(tokens, i, TT_DEFAULT, token, (int)(cursor - token)); continue; }
+		WHITE_SPACE	{ i = copyToken(tokens, i, TT_WHITE_SPACE, token, (int)(cursor - token)); continue; }
+		END_OF_LINE	{ i = copyToken(tokens, i, TT_END_OF_LINE, token, (int)(cursor - token)); continue; }
+*/
+	}
+
+	return i;
+}
+
+int copyToken(TOKEN *tokens, int index, TOKEN_TYPE type, const char *text, int length)
+{
+	if (index < TOKENS)
+	{
+		int i;
+
+		tokens[index].type = type;
+
+		for (i = 0; i < length && i + 1 < TOKEN_LEN; ++i)
+			tokens[index].text[i] = text[i];
+
+		tokens[index].text[i] = '\0';
+
+		++index;
+	}
+	return index;
+}
--- a/common-post-process/common-post-process.y
+++ b/common-post-process/common-post-process.y
@ -0,0 +1,172 @@
+%error-verbose
+
+%code requires {
+	#include "common-post-process.h"
+}
+
+%{
+	#include <stdlib.h>
+	#include <stdio.h>
+	#include <limits.h>
+	#include <math.h>
+
+	#include "common-post-process.h"
+	#include "common-post-process.yy.h"
+%}
+
+%union {
+	long long ival;
+	char sval[TOKEN_LEN];
+}
+
+%token <sval> CONSTANT IDENTIFIER
+%token LEFT_OP RIGHT_OP LE_OP GE_OP NE_OP AND_OP OR_OP
+
+%type <ival> expr primary_expr unary_expr mult_expr add_expr shift_expr rel_expr eq_expr and_expr xor_expr or_expr logical_and_expr logical_or_expr
+
+%start expr
+%%
+
+primary_expr
+	: '*'						{ fprintf(stderr, "SET (program counter * is not allowed)\n"); exit(1); }
+	| IDENTIFIER					{ fprintf(stderr, "SET (unsubstituted constant '%s', use #define)\n", $1); exit(1); }
+	| CONSTANT					{ $$ = parseCommon($1); }
+	| '(' expr ')'					{ $$ = $2; }
+	;
+
+unary_expr
+	: primary_expr
+	| '<' unary_expr				{ $$ = $2 & (0xff << INT_FRAC); }
+	| '>' unary_expr				{ $$ = $2 >> CHAR_BIT & (0xff << INT_FRAC); }
+	| '+' unary_expr				{ $$ = +$2; }
+	| '-' unary_expr				{ $$ = -$2; }
+	| '~' unary_expr				{ $$ = ~$2; }
+	| '!' unary_expr				{ $$ = !$2; }
+	;
+
+mult_expr
+	: unary_expr
+	| mult_expr '*' unary_expr			{ $$ = ($1 * $3) >> INT_FRAC; }
+	| mult_expr '/' unary_expr			{ $$ = ($1 << INT_FRAC) / $3; }
+	| mult_expr '%' unary_expr			{ $$ = $1 % $3; }
+	;
+
+add_expr
+	: mult_expr
+	| add_expr '+' mult_expr			{ $$ = $1 + $3; }
+	| add_expr '-' mult_expr			{ $$ = $1 - $3; }
+	;
+
+shift_expr
+	: add_expr
+	| shift_expr LEFT_OP add_expr			{ $$ = shiftCommon($1, +$3); }
+	| shift_expr RIGHT_OP add_expr			{ $$ = shiftCommon($1, -$3); }
+	;
+
+rel_expr
+	: shift_expr
+	| rel_expr '<' shift_expr			{ $$ = ($1 < $3)? 1: 0; }
+	| rel_expr '>' shift_expr			{ $$ = ($1 > $3)? 1: 0; }
+	| rel_expr LE_OP shift_expr			{ $$ = ($1 <= $3)? 1: 0; }
+	| rel_expr GE_OP shift_expr			{ $$ = ($1 >= $3)? 1: 0; }
+	;
+
+eq_expr
+	: rel_expr
+	| eq_expr '=' rel_expr				{ $$ = ($1 == $3)? 1: 0; }
+	| eq_expr NE_OP rel_expr			{ $$ = ($1 == $3)? 0: 1; }
+	;
+
+and_expr
+	: eq_expr
+	| and_expr '&' eq_expr				{ $$ = $1 & $3; }
+	;
+
+xor_expr
+	: and_expr
+	| xor_expr '^' and_expr				{ $$ = $1 ^ $3; }
+	;
+
+or_expr
+	: xor_expr
+	| or_expr '|' xor_expr				{ $$ = $1 | $3; }
+	;
+
+logical_and_expr
+	: or_expr
+	| logical_and_expr AND_OP or_expr		{ $$ = ($1 && $3)? 1: 0; }
+	;
+
+logical_or_expr
+	: logical_and_expr
+	| logical_or_expr OR_OP logical_and_expr	{ $$ = ($1 || $3)? 1: 0; }
+	;
+
+expr
+	: logical_or_expr				{ result = $1; }
+	;
+
+%%
+
+void yyerror(char const *s)
+{
+	fprintf (stderr, "SET (%s)\n", s);
+	exit(1);
+}
+
+long long parseCommon(const char *input)
+{
+	char digit[2] = {'\0', '\0'};
+	double base = 10.0, working = 0.0;
+	int sign;
+	long long output;
+	/* Check the first character for a base specification */
+	switch (*input) {
+		case '$':
+			base = 16.0;
+			++input;
+			break;
+		case '&':
+			base = 8.0;
+			++input;
+			break;
+		case '%':
+			base = 2.0;
+			++input;
+			break;
+	}
+	/* Get all the digits before the point */
+	while (*input && *input != '.') {
+		digit[0] = *input;
+		working = working * base + (double)strtol(digit, NULL, base);
+		++input;
+	}
+	/* Has a fraction? */
+	if (*input == '.') {
+		double fraction = 0.0, divisor = 1.0;
+		++input;
+		/* Get all the digits after the point */
+		while (*input) {
+			digit[0] = *input;
+			fraction = fraction * base + (double)strtol(digit, NULL, base);
+			divisor *= base;
+			++input;
+		}
+		/* Convert to fraction and add it */
+		working += fraction / divisor;
+	}
+	/* Convert to integer */
+	sign = (working < 0.0)? -1: +1;
+	output = sign * (long long)floor(fabs(working) * (double)(1 << INT_FRAC));
+	/* Done */
+	return output;
+}
+
+long long shiftCommon(long long base, long long amount)
+{
+	double scaling = (double)(1 << INT_FRAC);
+	double x = (double) base / scaling, y = (double) amount / scaling;
+	double working = x * pow(2.0, y);
+	int sign = (working < 0.0)? -1: +1;
+	return sign * (long long)floor(fabs(working) * scaling);
+}
--- a/common-post-process/main.c
+++ b/common-post-process/main.c
@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <limits.h>
+#include <string.h>
+
+#include "common-post-process.h"
+#include "common-post-process.yy.h"
+
+long long result;
+
+int main(int argc, char **argv)
+{
+	TOKEN tokens[TOKENS];
+	char buffer[IO_BUFFER] = {'\0'};
+
+	/* Process input */
+	while (fgets(buffer, IO_BUFFER, stdin))
+	{
+		/* Tokenize the line */
+		int count;
+		if (count = tokenizeInput(buffer, tokens))
+		{
+			/* Iterate through the tokens */
+			int i;
+			for (i = 0; i < count; ++i)
+			{
+				int j;
+				unsigned long working;
+				const char *s = "", *p, *q;
+				switch (tokens[i].type)
+				{
+					/* Process each _SET_V("<expr>") command */
+					case TT_COMMAND:
+						/* Extract the start and ending indices */
+						p = strchr(tokens[i].text, '"') + 1;
+						q = strrchr(tokens[i].text, '"');
+						/* Parse the input */
+						yyin = fmemopen((void *)p, q - p, "r");
+						yyparse();
+						fclose(yyin);
+						/* Output */
+						working = (unsigned long)((result >> (INT_FRAC - EXP_FRAC)) % (1 << EXP_FULL));
+						for (j = 0; j < EXP_FULL; j += CHAR_BIT)
+						{
+							printf("%s$%02lX", s, working & 0xff);
+							working >>= CHAR_BIT;
+							s = ", ";
+						}
+						break;
+					default:
+						/* Default, just print it */
+						printf("%s", tokens[i].text);
+						break;
+				}
+			}
+		}
+	}
+	return 0;
+}
--- a/common/Makefile
+++ b/common/Makefile
@ -0,0 +1,12 @@
+system.obj: common.obj page6.obj
+	cat common.obj page6.obj > system.obj
+
+common.obj: rom.h common.h common.asm
+	xa -M common.asm -l common.lbl -o common.obj
+
+page6.obj: rom.h macros.h page6.src
+	cpp -P page6.src | ./common-post-process > page6.asm
+	xa -M page6.asm -l page6.lbl -o page6.obj
+
+clean: 
+	rm -f page6.asm common.obj page6.obj common.lbl page6.lbl
--- a/common/common.asm
+++ b/common/common.asm
@ -0,0 +1,390 @@
+#include "rom.h"
+#include "common.h"
+
+	; ROM code header
+	.WORD CMN_CD, _END_CMN_CD - CMN_CD
+
+	; beginning of ROM code
+	* = CMN_CD
+
+_CMN	.(		; common function interpreter
+	JSR _SAV	; save registers
+	PLA
+	STA _PCL	; set program counter from return address
+	PLA
+	STA _PCH
+	INC _PCL	; advance the program counter
+	BNE _1
+	INC _PCH
+_1	JSR _2		; interpret and execute one common instruction
+	JMP _1
+_2	LDY #0
+	LDA (_PC),Y	; get operand
+	INC _PCL	; advance the program counter
+	BNE _3
+	INC _PCH
+_3	TAX		; save operand for later
+	AND #$F0
+	BEQ _4		; go to 0X instructions
+	CMP #$F0	; check for FX functions
+	BEQ _5		; go to FX instructions
+	LSR		; get offset to XR instructions
+	LSR
+	LSR
+	TAY
+	DEY
+	DEY
+	LDA FN_XR+1,Y	; push high address
+	PHA
+	LDA FN_XR,Y	; push low address
+	PHA
+	TXA		; restore operand
+	AND #$F		; mask to get register
+	ASL		; shift to get offset to register
+	ASL
+	TAX		; back to index
+	RTS		; "return" to routine	
+_4	TXA		; get operand
+	ASL		; shift to get offset to 0X instructions
+	TAY
+	LDA FN_0X+1,Y	; push high address
+	PHA
+	LDA FN_0X,Y	; push low address
+	PHA
+	TXA		; restore operand
+	RTS		; "return" to routine	
+_5	TXA		; get operand
+	AND #$F		; mask to get index
+	ASL		; shift to get offset to FX instructions
+	TAY
+	LDA FN_FX+1,Y	; push high address
+	PHA
+	LDA FN_FX,Y	; push low address
+	PHA
+	TXA		; restore operand
+	RTS		; "return" to routine
+.)
+
+_INI .(			; initialize common
+			; copy system functions (TODO)
+			; load program (TODO)
+	LDA #0		; clear RSI
+	STA _RSI
+	JMP (_PC)	; go to last loaded block
+.)
+
+_SAV	.(		; save the registers prior to entering common
+	STA _ACC
+	STX _IDX
+	STY _IDY
+	PHP
+	PLA
+	STA _PS
+	CLD
+	RTS
+.)
+
+_RES	.(		; restore the registers prior to leaving common
+	LDA _PS
+	PHA
+	LDA _ACC
+	LDX _IDX
+	LDY _IDY
+	PLP
+	RTS
+.)
+
+_SET	.(		; SET r aabbcc.dd	1r dd cc bb aa	Rr <- aabbcc.dd	- set register
+	LDY #0
+	LDA (_PC),Y	; transfer four bytes over
+	STA _R0,X
+	INY
+	LDA (_PC),Y
+	STA _R0+1,X
+	INY
+	LDA (_PC),Y
+	STA _R0+2,X
+	INY
+	LDA (_PC),Y
+	STA _R0+3,X
+	LDA #4		; update program counter
+	CLC
+	ADC _PCL
+	STA _PCL
+	BCC _1
+	INC _PCH
+_1	RTS		; done
+.)
+
+_POP	.(		; POP r			2r		Rr <- RS	- pop from stack
+	LDY _RSI	; get register stack index
+	DEY		; transfer four bytes over
+	LDA _RS,Y
+	STA _R0+3,X
+	DEY
+	LDA _RS,Y
+	STA _R0+2,X
+	DEY
+	LDA _RS,Y
+	STA _R0+1,X
+	DEY
+	LDA _RS,Y
+	STA _R0,X
+	STY _RSI	; update register stack index
+	RTS
+.)
+
+_PSH	.(		; PSH r			3r		RS <- Rr	- push onto stack
+	LDY _RSI	; get register stack index
+	LDA _R0,X	; transfer four bytes over
+	STA _RS,Y
+	INY
+	LDA _R0+1,X
+	STA _RS,Y
+	INY
+	LDA _R0+2,X
+	STA _RS,Y
+	INY
+	LDA _R0+3,X
+	STA _RS,Y
+	INY
+	STY _RSI	; update register stack index
+	RTS
+.)
+
+_EXC	.(		; EXC r			4r		Rr <-> RS	- exchange Rr with stack
+	LDY _RSI	; RS to RD
+	LDA _RS-1,Y
+	STA _RD+3
+	LDA _RS-2,Y
+	STA _RD+2
+	LDA _RS-3,Y
+	STA _RD+1
+	LDA _RS-4,Y
+	STA _RD
+	LDA _R0,X	; copy Rr to RS
+	STA _RS-4,Y
+	LDA _R0+1,X
+	STA _RS-3,Y
+	LDA _R0+2,X
+	STA _RS-2,Y
+	LDA _R0+3,X
+	STA _RS-1,Y
+	LDA _RD		; copy RD to Rr
+	STA _R0,X
+	LDA _RD+1
+	STA _R0+1,X
+	LDA _RD+2
+	STA _R0+2,X
+	LDA _RD+3
+	STA _R0+3,X
+	RTS
+.)
+
+_INR	.(		; INR r			5r		Rr <- Rr + 1.0	- increment register
+	LDA _R0+3,X
+	AND #_MSK_O	; check for existing overflow condition
+	BEQ _4
+	EOR #_MSK_O
+	BEQ _4
+	BNE _3		; existing overflow, skip increment operation
+_4	LDA #_PLS_1	; adding plus one
+	CLC
+	ADC _R0+1,X
+	STA _R0+1,X
+	BCC _1
+	LDA #0
+	ADC _R0+2,X
+	STA _R0+2,X
+	BCC _1
+	LDA #0
+	ADC _R0+3,X
+	STA _R0+3,X
+_1	LDA _R0+3,X
+	AND #_MSK_O	; check for overflow
+	BEQ _2
+	EOR #_MSK_O
+	BEQ _2
+_3	LDA _F		; set overflow
+	ORA #_F_O
+	STA _F
+	BNE _5
+_2	LDA _F		; clear overflow
+	AND #_F_O^$FF
+	STA _F
+_5	RTS
+.)
+
+_DCR	.(		; DCR r			6r		Rr <- Rr - 1.0	- decrement register
+	LDA _R0+3,X
+	AND #_MSK_U	; check for existing underflow condition
+	BEQ _4
+	EOR #_MSK_U
+	BEQ _4
+	BNE _3		; existing underflow, skip decrement operation
+_4	LDA #_MNS_1	; adding minus one
+	CLC
+	ADC _R0+1,X
+	STA _R0+1,X
+	LDA #$FF
+	ADC _R0+2,X
+	STA _R0+2,X
+	LDA #$FF
+	ADC _R0+3,X
+	STA _R0+3,X
+_1	LDA _R0+3,X
+	AND #_MSK_U	; check for underflow
+	BEQ _2
+	EOR #_MSK_U
+	BEQ _2
+_3	LDA _F		; set underflow
+	ORA #_F_U
+	STA _F
+	BNE _5
+_2	LDA _F		; clear underflow
+	AND #_F_U^$FF
+	STA _F
+_5	RTS
+.)
+
+_TST	.(		; TST r			7r		F <- Rr <=> 0.0	- test register
+	RTS
+.)
+
+_DEC	.(		; DEC r			8r		Rr <- dec(Rr)	- convert Rr from hex aabbcc.dd to decimal ######.##
+	RTS
+.)
+
+_HEX	.(		; HEX r			9r		Rr <- hex(Rr)	- convert Rr from decimal ######.## to hex aabbcc.dd
+	RTS
+.)
+
+_ADD	.(		; ADD r pq		ar pq		Rr <- Rp + Rq	- addition
+	RTS
+.)
+
+_SUB	.(		; SUB r pq		br pq		Rr <- Rp - Rq	- subtraction
+	RTS
+.)
+
+_MUL	.(		; MUL r pq		cr pq		Rr <- Rp * Rq	- multiplication
+	RTS
+.)
+
+_DIV	.(		; DIV r pq		dr pq		Rr <- Rp / Rq	- division
+	RTS
+.)
+
+_MOD	.(		; MOD r pq		er pq		Rr <- Rp % Rq	- modulus
+	RTS
+.)
+	
+_ESC	.(		; ESC			00				- escape back into regular assembler
+	PLA		; discard the COMMON _1 return address
+	PLA
+	JSR _RES	; restore the registers
+	JMP (_PC)	; get back in the code
+.)
+
+_RTN	.(		; RTN			01				- return from subroutine
+	RTS
+.)
+
+_BRS	.(		; BRS xxyy		02 yy xx	PC <- PC + xxyy	- branch to subroutine
+	RTS
+.)
+
+_BRA	.(		; BRA xxyy		03 yy xx	PC <- PC + xxyy	- branch always
+	RTS
+.)
+
+_BRE	.(		; BRE xxyy		04 yy xx	PC <- PC + xxyy	- branch if Rp = Rq (after CMP)
+	LDA #_F_E
+	BNE _BRX
+.)
+
+_BRG	.(		; BRG xxyy		05 yy xx	PC <- PC + xxyy	- branch if Rp > Rq (after CMP)
+	LDA #_F_G
+	BNE _BRX
+.)
+
+_BRL	.(		; BRL xxyy		06 yy xx	PC <- PC + xxyy	- branch if Rp < Rq (after CMP)
+	LDA #_F_L
+	BNE _BRX
+.)
+
+_BRZ	.(		; BRZ xxyy		07 yy xx	PC <- PC + xxyy	- branch if Rr = 0.0 (after TST)
+	LDA #_F_Z
+	BNE _BRX
+.)
+
+_BRP	.(		; BRP xxyy		08 yy xx	PC <- PC + xxyy	- branch if Rr > 0.0 (after TST)
+	LDA #_F_P
+	BNE _BRX
+.)
+
+_BRN	.(		; BRN xxyy		09 yy xx	PC <- PC + xxyy	- branch if Rr < 0.0 (after TST)
+	LDA #_F_N
+	BNE _BRX
+.)
+
+_BRO	.(		; BRO xxyy		0a yy xx	PC <- PC + xxyy	- branch if overflow (after arithmetic operations)
+	LDA #_F_O
+	BNE _BRX
+.)
+
+_BRU	.(		; BRU xxyy		0b yy xx	PC <- PC + xxyy	- branch if underflow (after arithmetic operations)
+	LDA #_F_U
+	BNE _BRX	; (TODO) this line can probably be removed
+.)
+
+_BRX	.(		; generic branch testing
+	AND _F		; check the bit
+	BNE _BRA	; if set, branch
+	INC _PCL	; not set, advance the program counter
+	BNE _1
+	INC _PCH
+_1	RTS
+.)
+
+_CPR	.(		; CPR pq		0c pq		Rp <- Rq	- copy register
+	RTS
+.)
+
+_LDI	.(		; LDI pq		0d pq		Rp <- (Rq:bbcc)	- load indirect from memory
+	RTS
+.)
+
+_SVI	.(		; SVI pq		0e pq		(Rp:bbcc) <- Rq	- save indirect to memory
+	RTS
+.)
+
+_CMR	.(		; CMR pq		0f pq		F <- Rp <=> Rq	- compare registers
+	RTS
+.)
+
+_END_CMN_CD
+
+	; ROM data header
+	.WORD CMN_DT, _END_CMN_DT - CMN_DT
+
+	; beginning of ROM data
+	* = CMN_DT
+
+FN_0X	.WORD _ESC-1, _RTN-1, _BRS-1, _BRA-1, _BRE-1, _BRG-1, _BRL-1, _BRZ-1,
+	.WORD _BRP-1, _BRN-1, _BRO-1, _BRU-1, _CPR-1, _LDI-1, _SVI-1, _CMR-1
+FN_XR	.WORD _SET-1, _POP-1, _PSH-1, _EXC-1, _INR-1, _DCR-1, _TST-1,
+	.WORD _DEC-1, _HEX-1, _ADD-1, _SUB-1, _MUL-1, _DIV-1, _MOD-1
+
+_END_CMN_DT
+
+	; 6502 addresses
+	.WORD ADDR, 6
+
+	; 6502 NMI, Reset and IRQ
+	* = $FFFA
+ADDR	.WORD 0, _INI, 0
+
+
+
+
--- a/common/common.h
+++ b/common/common.h
@ -0,0 +1,139 @@
+#ifndef __COMMON_H
+#define __COMMON_H
+
+; Using four byte quantities aabbccdd with one bit overflow/underflow, 21 bits significand, 10 bits fraction
+
+; Largest value:          $3fffffff or  1048575.999(9)
+; Smallest value:         $c0000001 or -1048575.999(0)
+; Largest value for DEC:  $3d08ffff or   999999.999(9)
+; Smallest value for DEC: $c2f70001 or  -999999.999(0)
+
+; Instructions
+
+; SET r aabbcc.dd	1r dd cc bb aa	Rr <- aabbccdd	- set register
+; POP r			2r		Rr <- RS	- pop from stack
+; PSH r			3r		RS <- Rr	- push onto stack
+; EXC r			4r		Rr <-> RS	- exchange Rr with stack
+; INR r			5r		Rr <- Rr + 1.0	- increment register
+; DCR r			6r		Rr <- Rr - 1.0	- decrement register
+; TST r			7r		F <- Rr <=> 0.0	- test register
+; DEC r			8r		Rr <- dec(Rr)	- convert Rr from hex aabbccdd to decimal #########
+; HEX r			9r		Rr <- hex(Rr)	- convert Rr from decimal ######### to hex aabbccdd
+; ADD r pq		ar pq		Rr <- Rp + Rq	- addition
+; SUB r pq		br pq		Rr <- Rp - Rq	- subtraction
+; MUL r pq		cr pq		Rr <- Rp * Rq	- multiplication
+; DIV r pq		dr pq		Rr <- Rp / Rq	- division
+; MOD r pq		er pq		Rr <- Rp % Rq	- modulus
+; EXT z	...		fz ...				- system and user defined functions
+
+; ESC			00				- escape back into regular assembler
+; RTN			01				- return from subroutine
+; BRS xxyy		02 yy xx	PC <- PC + xxyy	- branch to subroutine
+; BRA xxyy		03 yy xx	PC <- PC + xxyy	- branch always
+; BRE xxyy		04 yy xx	PC <- PC + xxyy	- branch if Rp = Rq (after CMR)
+; BRG xxyy		05 yy xx	PC <- PC + xxyy	- branch if Rp > Rq (after CMR)
+; BRL xxyy		06 yy xx	PC <- PC + xxyy	- branch if Rp < Rq (after CMR)
+; BRZ xxyy		07 yy xx	PC <- PC + xxyy	- branch if Rr = 0.0 (after TST)
+; BRP xxyy		08 yy xx	PC <- PC + xxyy	- branch if Rr > 0.0 (after TST)
+; BRN xxyy		09 yy xx	PC <- PC + xxyy	- branch if Rr < 0.0 (after TST)
+; BRO xxyy		0a yy xx	PC <- PC + xxyy	- branch if overflow (after arithmetic operations)
+; BRU xxyy		0b yy xx	PC <- PC + xxyy	- branch if underflow (after arithmetic operations)
+; CPR pq		0c pq		Rp <- Rq	- copy register
+; LDI pq		0d pq		Rp <- (int(Rq))	- load indirect from memory
+; SVI pq		0e pq		(int(Rp)) <- Rq	- save indirect to memory
+; CMR pq		0f pq		F <- Rp <=> Rq	- compare registers
+
+; 64 bytes in page zero for common registers
+_R0	= $C0
+_R1	= _R0 + 4
+_R2	= _R1 + 4
+_R3	= _R2 + 4
+_R4	= _R3 + 4
+_R5	= _R4 + 4
+_R6	= _R5 + 4
+_R7	= _R6 + 4
+_R8	= _R7 + 4
+_R9	= _R8 + 4
+_RA	= _R9 + 4
+_RB	= _RA + 4
+_RC	= _RB + 4	; workspace for arithmetic operations
+_RD	= _RC + 4	; as above and for EXC
+_RE	= _RD + 4	; register E maintains common status
+_RF	= _RE + 4	; register F saves/restores processor status
+
+; register E maintains common status
+; (dd cc bb aa) aa: index for register stack RS / ccbb: program counter PC / dd: flags F UONPZLGE
+_RSI	= _RE		; register stack index
+_PCL	= _RSI + 1	; program counter low
+_PCH	= _PCL + 1	; program counter high
+_F	= _PCH + 1	; flags
+_PC	= _PCL		; program counter
+
+; bits for flags
+_F_E	=   1		; if Rp = Rq (after CMP)
+_F_G	=   2		; if Rp > Rq (after CMP)
+_F_L	=   4		; if Rp < Rq (after CMP)
+_F_Z	=   8		; if Rr = 0.0 (after TST)
+_F_P	=  16		; if Rr > 0.0 (after TST)
+_F_N	=  32		; if Rr < 0.0 (after TST)
+_F_O	=  64		; if overflow (after arithmetic operations)
+_F_U	= 128		; if underflow (after arithmetic operations)
+
+; register F saves/restores processor status
+; (dd cc bb aa) aa: accumulator, bb: index X, cc: index Y, dd: processor status
+_ACC	= _RF		; saved accumulator to restore
+_IDX	= _ACC + 1	; saved index X to restore
+_IDY	= _IDX + 1	; saved index Y to restore
+_PS	= _IDY + 1	; saved processor status to restore
+
+; 256 bytes of page two
+_RS	= $200		; register stack
+
+; 64 bytes of page three
+FN_FX	= $300		; list of system and user functions
+
+; function constants
+_ESC_C	= $00
+_RTN_C	= $01
+_BRS_C	= $02
+_BRA_C	= $03
+_BRE_C	= $04
+_BRG_C	= $05
+_BRL_C	= $06
+_BRZ_C	= $07
+_BRP_C	= $08
+_BRN_C	= $09
+_BRO_C	= $0a
+_BRU_C	= $0b
+_CPR_C	= $0c
+_LDI_C	= $0d
+_SVI_C	= $0e
+_CMR_C	= $0f
+
+_SET_C	= $10
+_POP_C	= $20
+_PSH_C	= $30
+_EXC_C	= $40
+_INR_C	= $50
+_DCR_C	= $60
+_TST_C	= $70
+_DEC_C	= $80
+_HEX_C	= $90
+_ADD_C	= $a0
+_SUB_C	= $b0
+_MUL_C	= $c0
+_DIV_C	= $d0
+_MOD_C	= $e0
+_EXT_C	= $f0
+
+; common constants
+
+; plus and minus 1 for increment and decrement
+_PLS_1	= %00000100	; i.e. the $04 part of $00000400
+_MNS_1	= %11111100	; i.e. the $FC part of $FFFFFC00
+
+; masks for overflow and unerflow
+_MSK_O	= %11000000	; mask for overflow
+_MSK_U	= %11000000	; mask for underflow
+
+#endif /* __COMMON_H */
--- a/common/macros.h
+++ b/common/macros.h
@ -0,0 +1,98 @@
+#include "common.h"
+
+#ifndef MACROS_H
+#define MACROS_H
+
+; registers
+#define	R0		0
+#define	R1		1
+#define	R2		2
+#define	R3		3
+#define	R4		4
+#define	R5		5
+#define	R6		6
+#define	R7		7
+#define	R8		8
+#define	R9		9
+#define	RA		10
+#define	RB		11
+#define	RC		12
+#define	RD		13
+#define	RE		14
+#define	RF		15
+
+; system functions
+#define	S0		0
+#define	S1		1
+#define	S2		2
+#define	S3		3
+#define	S4		4
+#define	S5		5
+#define	S6		6
+#define	S7		7
+#define	S8		8
+#define	S9		9
+#define	SA		10
+#define	SB		11
+#define	SC		12
+#define	SD		13
+#define	SE		14
+#define	SF		15
+
+; user functions
+#define	U0		15
+#define	U1		14
+#define	U2		13
+#define	U3		12
+#define	U4		11
+#define	U5		10
+#define	U6		9
+#define	U7		8
+#define	U8		7
+#define	U9		6
+#define	UA		5
+#define	UB		4
+#define	UC		3
+#define	UD		2
+#define	UE		1
+#define	UF		0
+
+; macros
+#define ESC		.BYTE _ESC_C
+#define RTN		.BYTE _RTN_C
+#define BRS(o)		.BYTE _BRS_C, <(o - * - 3), >(o - * - 3)
+#define BRA(o)		.BYTE _BRA_C, <(o - * - 3), >(o - * - 3)
+#define BRE(o)		.BYTE _BRE_C, <(o - * - 3), >(o - * - 3)
+#define BRG(o)		.BYTE _BRG_C, <(o - * - 3), >(o - * - 3)
+#define BRL(o)		.BYTE _BRL_C, <(o - * - 3), >(o - * - 3)
+#define BRZ(o)		.BYTE _BRZ_C, <(o - * - 3), >(o - * - 3)
+#define BRP(o)		.BYTE _BRP_C, <(o - * - 3), >(o - * - 3)
+#define BRN(o)		.BYTE _BRN_C, <(o - * - 3), >(o - * - 3)
+#define BRO(o)		.BYTE _BRO_C, <(o - * - 3), >(o - * - 3)
+#define BRU(o)		.BYTE _BRU_C, <(o - * - 3), >(o - * - 3)
+#define CPR(p, q)	.BYTE _CPR_C, p * 16 + q
+#define LDI(p, q)	.BYTE _LDI_C, p * 16 + q
+#define SVI(p, q)	.BYTE _SVI_C, p * 16 + q
+#define CMR(p, q)	.BYTE _CMR_C, p * 16 + q
+#define SET(r, v)	.BYTE _SET_C + r, _SET_V(#v)
+#define POP(r)		.BYTE _POP_C + r
+#define PSH(r)		.BYTE _PSH_C + r
+#define EXC(r)		.BYTE _EXC_C + r
+#define INR(r)		.BYTE _INR_C + r
+#define DCR(r)		.BYTE _DCR_C + r
+#define TST(r)		.BYTE _TST_C + r
+#define DEC(r)		.BYTE _DEC_C + r
+#define HEX(r)		.BYTE _HEX_C + r
+#define ADD(r)		.BYTE _ADD_C + r
+#define SUB(r, p, q)	.BYTE _SUB_C + r, p * 16 + q
+#define MUL(r, p, q)	.BYTE _MUL_C + r, p * 16 + q
+#define DIV(r, p, q)	.BYTE _DIV_C + r, p * 16 + q
+#define MOD(r, p, q)	.BYTE _MOD_C + r, p * 16 + q
+#define EXT(f)		.BYTE _EXT_C + f
+
+; header, begin and end of blocks
+#define HDR(a)		.WORD a, _END_##a - a:* = * - 4:a .(
+#define BGN(a)		a .(
+#define END(a)		.):_END_##a
+
+#endif // MACROS_H
--- a/common/page6.src
+++ b/common/page6.src
@ -0,0 +1,36 @@
+#include "rom.h"
+#include "macros.h"
+
+	* = $600
+
+HDR(DEMO)
+	CMN
+	SET(R0, +1048575.999)
+	SET(R1, -1048575.999)
+	SET(R2, 0.0)
+	SET(R3, 0.0)
+	INR(R0)
+	DCR(R1)
+	INR(R2)
+	DCR(R3)
+	INR(R0)
+	DCR(R1)
+	ESC
+	BRK
+
+BGN(FACTORIAL)
+	SET(R1, $10.4456)
+	SET(R2, 1)
+	HEX(R1)
+	MOD(R3, R1, R2)
+	SUB(R1, R1, R3)
+_1	TST(R1)
+	BRZ(_2)
+	MUL(R2, R2, R1)
+	DEC(R1)
+	BRA(_1)
+_2	EXT(S0)
+	RTN
+END(FACTORIAL)
+
+END(DEMO)
--- a/common/rom.h
+++ b/common/rom.h
@ -0,0 +1,11 @@
+#ifndef __ROM_H
+#define __ROM_H
+
+; ROM addresses
+CMN_CD	= $F800
+CMN_DT	= $FF00
+
+; macros
+#define CMN	JSR CMN_CD
+
+#endif /* __ROM_H */
--- a/emulator/Makefile
+++ b/emulator/Makefile
@ -0,0 +1,3 @@
+emulator: emulator.h emulator.c main.c
+	gcc -o emulator emulator.c main.c
+
--- a/emulator/emulator.c
+++ b/emulator/emulator.c
@ -0,0 +1,964 @@
+/* Fake6502 CPU emulator core v1.1 *******************
+ * (c)2011 Mike Chambers (miker00lz@gmail.com)       *
+ *****************************************************
+ * v1.1 - Small bugfix in BIT opcode, but it was the *
+ *        difference between a few games in my NES   *
+ *        emulator working and being broken!         *
+ *        I went through the rest carefully again    *
+ *        after fixing it just to make sure I didn't *
+ *        have any other typos! (Dec. 17, 2011)      *
+ *                                                   *
+ * v1.0 - First release (Nov. 24, 2011)              *
+ *****************************************************
+ * LICENSE: This source code is released into the    *
+ * public domain, but if you use it please do give   *
+ * credit. I put a lot of effort into writing this!  *
+ *                                                   *
+ *****************************************************
+ * Fake6502 is a MOS Technology 6502 CPU emulation   *
+ * engine in C. It was written as part of a Nintendo *
+ * Entertainment System emulator I've been writing.  *
+ *                                                   *
+ * A couple important things to know about are two   *
+ * defines in the code. One is "UNDOCUMENTED" which, *
+ * when defined, allows Fake6502 to compile with     *
+ * full support for the more predictable             *
+ * undocumented instructions of the 6502. If it is   *
+ * undefined, undocumented opcodes just act as NOPs. *
+ *                                                   *
+ * The other define is "NES_CPU", which causes the   *
+ * code to compile without support for binary-coded  *
+ * decimal (BCD) support for the ADC and SBC         *
+ * opcodes. The Ricoh 2A03 CPU in the NES does not   *
+ * support BCD, but is otherwise identical to the    *
+ * standard MOS 6502. (Note that this define is      *
+ * enabled in this file if you haven't changed it    *
+ * yourself. If you're not emulating a NES, you      *
+ * should comment it out.)                           *
+ *                                                   *
+ * If you do discover an error in timing accuracy,   *
+ * or operation in general please e-mail me at the   *
+ * address above so that I can fix it. Thank you!    *
+ *                                                   *
+ *****************************************************
+ * Usage:                                            *
+ *                                                   *
+ * Fake6502 requires you to provide two external     *
+ * functions:                                        *
+ *                                                   *
+ * uint8_t read6502(uint16_t address)                *
+ * void write6502(uint16_t address, uint8_t value)   *
+ *                                                   *
+ * You may optionally pass Fake6502 the pointer to a *
+ * function which you want to be called after every  *
+ * emulated instruction. This function should be a   *
+ * void with no parameters expected to be passed to  *
+ * it.                                               *
+ *                                                   *
+ * This can be very useful. For example, in a NES    *
+ * emulator, you check the number of clock ticks     *
+ * that have passed so you can know when to handle   *
+ * APU events.                                       *
+ *                                                   *
+ * To pass Fake6502 this pointer, use the            *
+ * hookexternal(void *funcptr) function provided.    *
+ *                                                   *
+ * To disable the hook later, pass NULL to it.       *
+ *****************************************************
+ * Useful functions in this emulator:                *
+ *                                                   *
+ * void reset6502()                                  *
+ *   - Call this once before you begin execution.    *
+ *                                                   *
+ * void exec6502(uint32_t tickcount)                 *
+ *   - Execute 6502 code up to the next specified    *
+ *     count of clock ticks.                         *
+ *                                                   *
+ * void step6502()                                   *
+ *   - Execute a single instrution.                  *
+ *                                                   *
+ * void irq6502()                                    *
+ *   - Trigger a hardware IRQ in the 6502 core.      *
+ *                                                   *
+ * void nmi6502()                                    *
+ *   - Trigger an NMI in the 6502 core.              *
+ *                                                   *
+ * void hookexternal(void *funcptr)                  *
+ *   - Pass a pointer to a void function taking no   *
+ *     parameters. This will cause Fake6502 to call  *
+ *     that function once after each emulated        *
+ *     instruction.                                  *
+ *                                                   *
+ *****************************************************
+ * Useful variables in this emulator:                *
+ *                                                   *
+ * uint32_t clockticks6502                           *
+ *   - A running total of the emulated cycle count.  *
+ *                                                   *
+ * uint32_t instructions                             *
+ *   - A running total of the total emulated         *
+ *     instruction count. This is not related to     *
+ *     clock cycle timing.                           *
+ *                                                   *
+ *****************************************************/
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include "emulator.h"
+
+#define FLAG_CARRY     0x01
+#define FLAG_ZERO      0x02
+#define FLAG_INTERRUPT 0x04
+#define FLAG_DECIMAL   0x08
+#define FLAG_BREAK     0x10
+#define FLAG_CONSTANT  0x20
+#define FLAG_OVERFLOW  0x40
+#define FLAG_SIGN      0x80
+
+#define BASE_STACK     0x100
+
+#define saveaccum(n) a = (uint8_t)((n) & 0x00FF)
+
+
+//flag modifier macros
+#define setcarry() status |= FLAG_CARRY
+#define clearcarry() status &= (~FLAG_CARRY)
+#define setzero() status |= FLAG_ZERO
+#define clearzero() status &= (~FLAG_ZERO)
+#define setinterrupt() status |= FLAG_INTERRUPT
+#define clearinterrupt() status &= (~FLAG_INTERRUPT)
+#define setdecimal() status |= FLAG_DECIMAL
+#define cleardecimal() status &= (~FLAG_DECIMAL)
+#define setoverflow() status |= FLAG_OVERFLOW
+#define clearoverflow() status &= (~FLAG_OVERFLOW)
+#define setsign() status |= FLAG_SIGN
+#define clearsign() status &= (~FLAG_SIGN)
+
+
+//flag calculation macros
+#define zerocalc(n) {\
+    if ((n) & 0x00FF) clearzero();\
+        else setzero();\
+}
+
+#define signcalc(n) {\
+    if ((n) & 0x0080) setsign();\
+        else clearsign();\
+}
+
+#define carrycalc(n) {\
+    if ((n) & 0xFF00) setcarry();\
+        else clearcarry();\
+}
+
+#define overflowcalc(n, m, o) { /* n = result, m = accumulator, o = memory */ \
+    if (((n) ^ (uint16_t)(m)) & ((n) ^ (o)) & 0x0080) setoverflow();\
+        else clearoverflow();\
+}
+
+
+//6502 CPU registers
+uint16_t pc;
+uint8_t sp, a, x, y, status;
+
+
+//helper variables
+uint32_t instructions = 0; //keep track of total instructions executed
+uint32_t clockticks6502 = 0, clockgoal6502 = 0;
+uint16_t oldpc, ea, reladdr, value, result;
+uint8_t opcode, oldstatus;
+
+//externally supplied functions
+extern uint8_t read6502(uint16_t address);
+extern void write6502(uint16_t address, uint8_t value);
+
+//a few general functions used by various other functions
+void push16(uint16_t pushval) {
+    write6502(BASE_STACK + sp, (pushval >> 8) & 0xFF);
+    write6502(BASE_STACK + ((sp - 1) & 0xFF), pushval & 0xFF);
+    sp -= 2;
+}
+
+void push8(uint8_t pushval) {
+    write6502(BASE_STACK + sp--, pushval);
+}
+
+uint16_t pull16() {
+    uint16_t temp16;
+    temp16 = read6502(BASE_STACK + ((sp + 1) & 0xFF)) | ((uint16_t)read6502(BASE_STACK + ((sp + 2) & 0xFF)) << 8);
+    sp += 2;
+    return(temp16);
+}
+
+uint8_t pull8() {
+    return (read6502(BASE_STACK + ++sp));
+}
+
+void reset6502() {
+    pc = (uint16_t)read6502(0xFFFC) | ((uint16_t)read6502(0xFFFD) << 8);
+    a = 0;
+    x = 0;
+    y = 0;
+    sp = 0xFD;
+    status |= FLAG_CONSTANT;
+}
+
+
+static void (*addrtable[256])();
+static void (*optable[256])();
+uint8_t penaltyop, penaltyaddr;
+
+//addressing mode functions, calculates effective addresses
+static void imp() { //implied
+}
+
+static void acc() { //accumulator
+}
+
+static void imm() { //immediate
+    ea = pc++;
+}
+
+static void zp() { //zero-page
+    ea = (uint16_t)read6502((uint16_t)pc++);
+}
+
+static void zpx() { //zero-page,X
+    ea = ((uint16_t)read6502((uint16_t)pc++) + (uint16_t)x) & 0xFF; //zero-page wraparound
+}
+
+static void zpy() { //zero-page,Y
+    ea = ((uint16_t)read6502((uint16_t)pc++) + (uint16_t)y) & 0xFF; //zero-page wraparound
+}
+
+static void rel() { //relative for branch ops (8-bit immediate value, sign-extended)
+    reladdr = (uint16_t)read6502(pc++);
+    if (reladdr & 0x80) reladdr |= 0xFF00;
+}
+
+static void abso() { //absolute
+    ea = (uint16_t)read6502(pc) | ((uint16_t)read6502(pc+1) << 8);
+    pc += 2;
+}
+
+static void absx() { //absolute,X
+    uint16_t startpage;
+    ea = ((uint16_t)read6502(pc) | ((uint16_t)read6502(pc+1) << 8));
+    startpage = ea & 0xFF00;
+    ea += (uint16_t)x;
+
+    if (startpage != (ea & 0xFF00)) { //one cycle penlty for page-crossing on some opcodes
+        penaltyaddr = 1;
+    }
+
+    pc += 2;
+}
+
+static void absy() { //absolute,Y
+    uint16_t startpage;
+    ea = ((uint16_t)read6502(pc) | ((uint16_t)read6502(pc+1) << 8));
+    startpage = ea & 0xFF00;
+    ea += (uint16_t)y;
+
+    if (startpage != (ea & 0xFF00)) { //one cycle penlty for page-crossing on some opcodes
+        penaltyaddr = 1;
+    }
+
+    pc += 2;
+}
+
+static void ind() { //indirect
+    uint16_t eahelp, eahelp2;
+    eahelp = (uint16_t)read6502(pc) | (uint16_t)((uint16_t)read6502(pc+1) << 8);
+    eahelp2 = (eahelp & 0xFF00) | ((eahelp + 1) & 0x00FF); //replicate 6502 page-boundary wraparound bug
+    ea = (uint16_t)read6502(eahelp) | ((uint16_t)read6502(eahelp2) << 8);
+    pc += 2;
+}
+
+static void indx() { // (indirect,X)
+    uint16_t eahelp;
+    eahelp = (uint16_t)(((uint16_t)read6502(pc++) + (uint16_t)x) & 0xFF); //zero-page wraparound for table pointer
+    ea = (uint16_t)read6502(eahelp & 0x00FF) | ((uint16_t)read6502((eahelp+1) & 0x00FF) << 8);
+}
+
+static void indy() { // (indirect),Y
+    uint16_t eahelp, eahelp2, startpage;
+    eahelp = (uint16_t)read6502(pc++);
+    eahelp2 = (eahelp & 0xFF00) | ((eahelp + 1) & 0x00FF); //zero-page wraparound
+    ea = (uint16_t)read6502(eahelp) | ((uint16_t)read6502(eahelp2) << 8);
+    startpage = ea & 0xFF00;
+    ea += (uint16_t)y;
+
+    if (startpage != (ea & 0xFF00)) { //one cycle penlty for page-crossing on some opcodes
+        penaltyaddr = 1;
+    }
+}
+
+static uint16_t getvalue() {
+    if (addrtable[opcode] == acc) return((uint16_t)a);
+        else return((uint16_t)read6502(ea));
+}
+
+static uint16_t getvalue16() {
+    return((uint16_t)read6502(ea) | ((uint16_t)read6502(ea+1) << 8));
+}
+
+static void putvalue(uint16_t saveval) {
+    if (addrtable[opcode] == acc) a = (uint8_t)(saveval & 0x00FF);
+        else write6502(ea, (saveval & 0x00FF));
+}
+
+
+//instruction handler functions
+static void adc() {
+    penaltyop = 1;
+    value = getvalue();
+    result = (uint16_t)a + value + (uint16_t)(status & FLAG_CARRY);
+   
+    carrycalc(result);
+    zerocalc(result);
+    overflowcalc(result, a, value);
+    signcalc(result);
+    
+    #ifndef NES_CPU
+    if (status & FLAG_DECIMAL) {
+        clearcarry();
+        
+        if ((a & 0x0F) > 0x09) {
+            a += 0x06;
+        }
+        if ((a & 0xF0) > 0x90) {
+            a += 0x60;
+            setcarry();
+        }
+        
+        clockticks6502++;
+    }
+    #endif
+   
+    saveaccum(result);
+}
+
+static void and() {
+    penaltyop = 1;
+    value = getvalue();
+    result = (uint16_t)a & value;
+   
+    zerocalc(result);
+    signcalc(result);
+   
+    saveaccum(result);
+}
+
+static void asl() {
+    value = getvalue();
+    result = value << 1;
+
+    carrycalc(result);
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void bcc() {
+    if ((status & FLAG_CARRY) == 0) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void bcs() {
+    if ((status & FLAG_CARRY) == FLAG_CARRY) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void beq() {
+    if ((status & FLAG_ZERO) == FLAG_ZERO) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void bit() {
+    value = getvalue();
+    result = (uint16_t)a & value;
+   
+    zerocalc(result);
+    status = (status & 0x3F) | (uint8_t)(value & 0xC0);
+}
+
+static void bmi() {
+    if ((status & FLAG_SIGN) == FLAG_SIGN) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void bne() {
+    if ((status & FLAG_ZERO) == 0) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void bpl() {
+    if ((status & FLAG_SIGN) == 0) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void brk() {
+    pc++;
+    push16(pc); //push next instruction address onto stack
+    push8(status | FLAG_BREAK); //push CPU status to stack
+    setinterrupt(); //set interrupt flag
+    pc = (uint16_t)read6502(0xFFFE) | ((uint16_t)read6502(0xFFFF) << 8);
+}
+
+static void bvc() {
+    if ((status & FLAG_OVERFLOW) == 0) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void bvs() {
+    if ((status & FLAG_OVERFLOW) == FLAG_OVERFLOW) {
+        oldpc = pc;
+        pc += reladdr;
+        if ((oldpc & 0xFF00) != (pc & 0xFF00)) clockticks6502 += 2; //check if jump crossed a page boundary
+            else clockticks6502++;
+    }
+}
+
+static void clc() {
+    clearcarry();
+}
+
+static void cld() {
+    cleardecimal();
+}
+
+static void cli() {
+    clearinterrupt();
+}
+
+static void clv() {
+    clearoverflow();
+}
+
+static void cmp() {
+    penaltyop = 1;
+    value = getvalue();
+    result = (uint16_t)a - value;
+   
+    if (a >= (uint8_t)(value & 0x00FF)) setcarry();
+        else clearcarry();
+    if (a == (uint8_t)(value & 0x00FF)) setzero();
+        else clearzero();
+    signcalc(result);
+}
+
+static void cpx() {
+    value = getvalue();
+    result = (uint16_t)x - value;
+   
+    if (x >= (uint8_t)(value & 0x00FF)) setcarry();
+        else clearcarry();
+    if (x == (uint8_t)(value & 0x00FF)) setzero();
+        else clearzero();
+    signcalc(result);
+}
+
+static void cpy() {
+    value = getvalue();
+    result = (uint16_t)y - value;
+   
+    if (y >= (uint8_t)(value & 0x00FF)) setcarry();
+        else clearcarry();
+    if (y == (uint8_t)(value & 0x00FF)) setzero();
+        else clearzero();
+    signcalc(result);
+}
+
+static void dec() {
+    value = getvalue();
+    result = value - 1;
+   
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void dex() {
+    x--;
+   
+    zerocalc(x);
+    signcalc(x);
+}
+
+static void dey() {
+    y--;
+   
+    zerocalc(y);
+    signcalc(y);
+}
+
+static void eor() {
+    penaltyop = 1;
+    value = getvalue();
+    result = (uint16_t)a ^ value;
+   
+    zerocalc(result);
+    signcalc(result);
+   
+    saveaccum(result);
+}
+
+static void inc() {
+    value = getvalue();
+    result = value + 1;
+   
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void inx() {
+    x++;
+   
+    zerocalc(x);
+    signcalc(x);
+}
+
+static void iny() {
+    y++;
+   
+    zerocalc(y);
+    signcalc(y);
+}
+
+static void jmp() {
+    pc = ea;
+}
+
+static void jsr() {
+    push16(pc - 1);
+    pc = ea;
+}
+
+static void lda() {
+    penaltyop = 1;
+    value = getvalue();
+    a = (uint8_t)(value & 0x00FF);
+   
+    zerocalc(a);
+    signcalc(a);
+}
+
+static void ldx() {
+    penaltyop = 1;
+    value = getvalue();
+    x = (uint8_t)(value & 0x00FF);
+   
+    zerocalc(x);
+    signcalc(x);
+}
+
+static void ldy() {
+    penaltyop = 1;
+    value = getvalue();
+    y = (uint8_t)(value & 0x00FF);
+   
+    zerocalc(y);
+    signcalc(y);
+}
+
+static void lsr() {
+    value = getvalue();
+    result = value >> 1;
+   
+    if (value & 1) setcarry();
+        else clearcarry();
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void nop() {
+    switch (opcode) {
+        case 0x1C:
+        case 0x3C:
+        case 0x5C:
+        case 0x7C:
+        case 0xDC:
+        case 0xFC:
+            penaltyop = 1;
+            break;
+    }
+}
+
+static void ora() {
+    penaltyop = 1;
+    value = getvalue();
+    result = (uint16_t)a | value;
+   
+    zerocalc(result);
+    signcalc(result);
+   
+    saveaccum(result);
+}
+
+static void pha() {
+    push8(a);
+}
+
+static void php() {
+    push8(status | FLAG_BREAK);
+}
+
+static void pla() {
+    a = pull8();
+   
+    zerocalc(a);
+    signcalc(a);
+}
+
+static void plp() {
+    status = pull8() | FLAG_CONSTANT;
+}
+
+static void rol() {
+    value = getvalue();
+    result = (value << 1) | (status & FLAG_CARRY);
+   
+    carrycalc(result);
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void ror() {
+    value = getvalue();
+    result = (value >> 1) | ((status & FLAG_CARRY) << 7);
+   
+    if (value & 1) setcarry();
+        else clearcarry();
+    zerocalc(result);
+    signcalc(result);
+   
+    putvalue(result);
+}
+
+static void rti() {
+    status = pull8();
+    value = pull16();
+    pc = value;
+}
+
+static void rts() {
+    value = pull16();
+    pc = value + 1;
+}
+
+static void sbc() {
+    penaltyop = 1;
+    value = getvalue() ^ 0x00FF;
+    result = (uint16_t)a + value + (uint16_t)(status & FLAG_CARRY);
+   
+    carrycalc(result);
+    zerocalc(result);
+    overflowcalc(result, a, value);
+    signcalc(result);
+
+    #ifndef NES_CPU
+    if (status & FLAG_DECIMAL) {
+        clearcarry();
+        
+        a -= 0x66;
+        if ((a & 0x0F) > 0x09) {
+            a += 0x06;
+        }
+        if ((a & 0xF0) > 0x90) {
+            a += 0x60;
+            setcarry();
+        }
+        
+        clockticks6502++;
+    }
+    #endif
+   
+    saveaccum(result);
+}
+
+static void sec() {
+    setcarry();
+}
+
+static void sed() {
+    setdecimal();
+}
+
+static void sei() {
+    setinterrupt();
+}
+
+static void sta() {
+    putvalue(a);
+}
+
+static void stx() {
+    putvalue(x);
+}
+
+static void sty() {
+    putvalue(y);
+}
+
+static void tax() {
+    x = a;
+   
+    zerocalc(x);
+    signcalc(x);
+}
+
+static void tay() {
+    y = a;
+   
+    zerocalc(y);
+    signcalc(y);
+}
+
+static void tsx() {
+    x = sp;
+   
+    zerocalc(x);
+    signcalc(x);
+}
+
+static void txa() {
+    a = x;
+   
+    zerocalc(a);
+    signcalc(a);
+}
+
+static void txs() {
+    sp = x;
+}
+
+static void tya() {
+    a = y;
+   
+    zerocalc(a);
+    signcalc(a);
+}
+
+//undocumented instructions
+#ifdef UNDOCUMENTED
+    static void lax() {
+        lda();
+        ldx();
+    }
+
+    static void sax() {
+        sta();
+        stx();
+        putvalue(a & x);
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void dcp() {
+        dec();
+        cmp();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void isb() {
+        inc();
+        sbc();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void slo() {
+        asl();
+        ora();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void rla() {
+        rol();
+        and();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void sre() {
+        lsr();
+        eor();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+
+    static void rra() {
+        ror();
+        adc();
+        if (penaltyop && penaltyaddr) clockticks6502--;
+    }
+#else
+    #define lax nop
+    #define sax nop
+    #define dcp nop
+    #define isb nop
+    #define slo nop
+    #define rla nop
+    #define sre nop
+    #define rra nop
+#endif
+
+
+static void (*addrtable[256])() = {
+/*        |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  A  |  B  |  C  |  D  |  E  |  F  |     */
+/* 0 */     imp, indx,  imp, indx,   zp,   zp,   zp,   zp,  imp,  imm,  acc,  imm, abso, abso, abso, abso, /* 0 */
+/* 1 */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx, /* 1 */
+/* 2 */    abso, indx,  imp, indx,   zp,   zp,   zp,   zp,  imp,  imm,  acc,  imm, abso, abso, abso, abso, /* 2 */
+/* 3 */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx, /* 3 */
+/* 4 */     imp, indx,  imp, indx,   zp,   zp,   zp,   zp,  imp,  imm,  acc,  imm, abso, abso, abso, abso, /* 4 */
+/* 5 */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx, /* 5 */
+/* 6 */     imp, indx,  imp, indx,   zp,   zp,   zp,   zp,  imp,  imm,  acc,  imm,  ind, abso, abso, abso, /* 6 */
+/* 7 */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx, /* 7 */
+/* 8 */     imm, indx,  imm, indx,   zp,   zp,   zp,   zp,  imp,  imm,  imp,  imm, abso, abso, abso, abso, /* 8 */
+/* 9 */     rel, indy,  imp, indy,  zpx,  zpx,  zpy,  zpy,  imp, absy,  imp, absy, absx, absx, absy, absy, /* 9 */
+/* A */     imm, indx,  imm, indx,   zp,   zp,   zp,   zp,  imp,  imm,  imp,  imm, abso, abso, abso, abso, /* A */
+/* B */     rel, indy,  imp, indy,  zpx,  zpx,  zpy,  zpy,  imp, absy,  imp, absy, absx, absx, absy, absy, /* B */
+/* C */     imm, indx,  imm, indx,   zp,   zp,   zp,   zp,  imp,  imm,  imp,  imm, abso, abso, abso, abso, /* C */
+/* D */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx, /* D */
+/* E */     imm, indx,  imm, indx,   zp,   zp,   zp,   zp,  imp,  imm,  imp,  imm, abso, abso, abso, abso, /* E */
+/* F */     rel, indy,  imp, indy,  zpx,  zpx,  zpx,  zpx,  imp, absy,  imp, absy, absx, absx, absx, absx  /* F */
+};
+
+static void (*optable[256])() = {
+/*        |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  A  |  B  |  C  |  D  |  E  |  F  |      */
+/* 0 */      brk,  ora,  nop,  slo,  nop,  ora,  asl,  slo,  php,  ora,  asl,  nop,  nop,  ora,  asl,  slo, /* 0 */
+/* 1 */      bpl,  ora,  nop,  slo,  nop,  ora,  asl,  slo,  clc,  ora,  nop,  slo,  nop,  ora,  asl,  slo, /* 1 */
+/* 2 */      jsr,  and,  nop,  rla,  bit,  and,  rol,  rla,  plp,  and,  rol,  nop,  bit,  and,  rol,  rla, /* 2 */
+/* 3 */      bmi,  and,  nop,  rla,  nop,  and,  rol,  rla,  sec,  and,  nop,  rla,  nop,  and,  rol,  rla, /* 3 */
+/* 4 */      rti,  eor,  nop,  sre,  nop,  eor,  lsr,  sre,  pha,  eor,  lsr,  nop,  jmp,  eor,  lsr,  sre, /* 4 */
+/* 5 */      bvc,  eor,  nop,  sre,  nop,  eor,  lsr,  sre,  cli,  eor,  nop,  sre,  nop,  eor,  lsr,  sre, /* 5 */
+/* 6 */      rts,  adc,  nop,  rra,  nop,  adc,  ror,  rra,  pla,  adc,  ror,  nop,  jmp,  adc,  ror,  rra, /* 6 */
+/* 7 */      bvs,  adc,  nop,  rra,  nop,  adc,  ror,  rra,  sei,  adc,  nop,  rra,  nop,  adc,  ror,  rra, /* 7 */
+/* 8 */      nop,  sta,  nop,  sax,  sty,  sta,  stx,  sax,  dey,  nop,  txa,  nop,  sty,  sta,  stx,  sax, /* 8 */
+/* 9 */      bcc,  sta,  nop,  nop,  sty,  sta,  stx,  sax,  tya,  sta,  txs,  nop,  nop,  sta,  nop,  nop, /* 9 */
+/* A */      ldy,  lda,  ldx,  lax,  ldy,  lda,  ldx,  lax,  tay,  lda,  tax,  nop,  ldy,  lda,  ldx,  lax, /* A */
+/* B */      bcs,  lda,  nop,  lax,  ldy,  lda,  ldx,  lax,  clv,  lda,  tsx,  lax,  ldy,  lda,  ldx,  lax, /* B */
+/* C */      cpy,  cmp,  nop,  dcp,  cpy,  cmp,  dec,  dcp,  iny,  cmp,  dex,  nop,  cpy,  cmp,  dec,  dcp, /* C */
+/* D */      bne,  cmp,  nop,  dcp,  nop,  cmp,  dec,  dcp,  cld,  cmp,  nop,  dcp,  nop,  cmp,  dec,  dcp, /* D */
+/* E */      cpx,  sbc,  nop,  isb,  cpx,  sbc,  inc,  isb,  inx,  sbc,  nop,  sbc,  cpx,  sbc,  inc,  isb, /* E */
+/* F */      beq,  sbc,  nop,  isb,  nop,  sbc,  inc,  isb,  sed,  sbc,  nop,  isb,  nop,  sbc,  inc,  isb  /* F */
+};
+
+static const uint32_t ticktable[256] = {
+/*        |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  |  A  |  B  |  C  |  D  |  E  |  F  |     */
+/* 0 */      7,    6,    2,    8,    3,    3,    5,    5,    3,    2,    2,    2,    4,    4,    6,    6,  /* 0 */
+/* 1 */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7,  /* 1 */
+/* 2 */      6,    6,    2,    8,    3,    3,    5,    5,    4,    2,    2,    2,    4,    4,    6,    6,  /* 2 */
+/* 3 */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7,  /* 3 */
+/* 4 */      6,    6,    2,    8,    3,    3,    5,    5,    3,    2,    2,    2,    3,    4,    6,    6,  /* 4 */
+/* 5 */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7,  /* 5 */
+/* 6 */      6,    6,    2,    8,    3,    3,    5,    5,    4,    2,    2,    2,    5,    4,    6,    6,  /* 6 */
+/* 7 */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7,  /* 7 */
+/* 8 */      2,    6,    2,    6,    3,    3,    3,    3,    2,    2,    2,    2,    4,    4,    4,    4,  /* 8 */
+/* 9 */      2,    6,    2,    6,    4,    4,    4,    4,    2,    5,    2,    5,    5,    5,    5,    5,  /* 9 */
+/* A */      2,    6,    2,    6,    3,    3,    3,    3,    2,    2,    2,    2,    4,    4,    4,    4,  /* A */
+/* B */      2,    5,    2,    5,    4,    4,    4,    4,    2,    4,    2,    4,    4,    4,    4,    4,  /* B */
+/* C */      2,    6,    2,    8,    3,    3,    5,    5,    2,    2,    2,    2,    4,    4,    6,    6,  /* C */
+/* D */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7,  /* D */
+/* E */      2,    6,    2,    8,    3,    3,    5,    5,    2,    2,    2,    2,    4,    4,    6,    6,  /* E */
+/* F */      2,    5,    2,    8,    4,    4,    6,    6,    2,    4,    2,    7,    4,    4,    7,    7   /* F */
+};
+
+
+void nmi6502() {
+    push16(pc);
+    push8(status);
+    status |= FLAG_INTERRUPT;
+    pc = (uint16_t)read6502(0xFFFA) | ((uint16_t)read6502(0xFFFB) << 8);
+}
+
+void irq6502() {
+    push16(pc);
+    push8(status);
+    status |= FLAG_INTERRUPT;
+    pc = (uint16_t)read6502(0xFFFE) | ((uint16_t)read6502(0xFFFF) << 8);
+}
+
+uint8_t callexternal = 0;
+void (*loopexternal)();
+
+void exec6502(uint32_t tickcount) {
+    clockgoal6502 += tickcount;
+   
+    while (clockticks6502 < clockgoal6502) {
+        opcode = read6502(pc++);
+        status |= FLAG_CONSTANT;
+
+        penaltyop = 0;
+        penaltyaddr = 0;
+
+        (*addrtable[opcode])();
+        (*optable[opcode])();
+        clockticks6502 += ticktable[opcode];
+        if (penaltyop && penaltyaddr) clockticks6502++;
+
+        instructions++;
+
+        if (callexternal) (*loopexternal)();
+    }
+
+}
+
+void step6502() {
+    opcode = read6502(pc++);
+    status |= FLAG_CONSTANT;
+
+    penaltyop = 0;
+    penaltyaddr = 0;
+
+    (*addrtable[opcode])();
+    (*optable[opcode])();
+    clockticks6502 += ticktable[opcode];
+    if (penaltyop && penaltyaddr) clockticks6502++;
+    clockgoal6502 = clockticks6502;
+
+    instructions++;
+
+    if (callexternal) (*loopexternal)();
+}
+
+void hookexternal(void *funcptr) {
+    if (funcptr != (void *)NULL) {
+        loopexternal = funcptr;
+        callexternal = 1;
+    } else callexternal = 0;
+}
--- a/emulator/emulator.h
+++ b/emulator/emulator.h
@ -0,0 +1,52 @@
+#ifndef __EMULATOR_H
+#define __EMULATOR_H
+
+#include <stdint.h>
+
+/* Accessing memory */
+extern uint8_t read6502(uint16_t address);
+extern void write6502(uint16_t address, uint8_t value);
+
+/* Call this once before you begin execution. */
+void reset6502();
+
+/* Execute 6502 code up to the next specified count of clock ticks. */
+void exec6502(uint32_t tickcount);
+
+/* Execute a single instrution. */
+void step6502();
+
+/* Trigger a hardware IRQ in the 6502 core. */
+void irq6502();
+
+/* Trigger an NMI in the 6502 core. */
+void nmi6502();
+
+/* Pass a pointer to a void function taking no parameters. This will
+   cause Fake6502 to call that function once after each emulated
+   instruction. */
+void hookexternal(void *funcptr);
+
+/* Useful variables in this emulator */
+
+/* Running total of the emulated cycle count. */
+extern uint32_t clockticks6502;
+
+/* Running total of the total emulated instruction count. This is not
+   related to clock cycle timing. */
+extern uint32_t instructions;
+
+/* When this is defined, undocumented opcodes are handled otherwise,
+   they're simply treated as NOPs. */
+#define UNDOCUMENTED
+
+/* When this is defined, the binary-coded decimal (BCD) status flag
+   is not honored by ADC and SBC. The 2A03 CPU in the Nintendo
+   Entertainment System does not support BCD operation. */
+#undef NES_CPU
+
+/* 6502 CPU registers */
+extern uint16_t pc;
+extern uint8_t sp, a, x, y, status;
+
+#endif /* __EMULATOR_H */
--- a/emulator/main.c
+++ b/emulator/main.c
@ -0,0 +1,63 @@
+#include <stdint.h>
+#include <stdio.h>
+#include "emulator.h"
+
+/* Register E maintains common status */
+#define _RE	0xf8
+
+/* (dd cc bb aa) aa: index for register stack RS / ccbb: program counter PC / dd: flags F UONPZLGE */
+#define _RSI	_RE		/* register stack index */
+#define _PCL	_RSI + 1	/* program counter low */
+#define _PCH	_PCL + 1	/* program counter high */
+#define _F	_PCH + 1	/* flags */
+#define _PC	_PCL		/* program counter */
+
+uint8_t memory[65536];
+
+uint8_t read6502(uint16_t address) {
+	return memory[address];
+}
+
+void write6502(uint16_t address, uint8_t value) {
+	memory[address] = value;
+}
+
+void hook() {
+	int i, j;
+
+	printf("\n%04x %u %u\n", pc, instructions, clockticks6502);
+	for (i = 0x00c0; i < 0x0100; i += 16) {
+		printf("%04x ", i);
+		for (j = 0; j < 16; ++j)
+			printf("%02x%s", memory[i + j], (i + j + 1) % 16? " ": "\n");
+	}
+}
+
+int main() {
+
+	uint8_t header[4];
+
+	while (fread(header, sizeof(header), 1, stdin))
+	{
+		uint16_t index = header[0] + (header[1] << 8);
+		uint16_t length = header[2] + (header[3] << 8);
+
+		printf("\n%04x %u\n", index, length);
+
+		if (fread(memory + index, length, 1, stdin))
+		{
+			memory[_PCL] = 	header[0];
+			memory[_PCH] = 	header[1];
+		}
+	}
+
+	hookexternal(hook);
+
+	reset6502();
+
+	do
+		step6502();
+	while (memory[pc]);
+
+	return 0;
+}