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Start stored program work.
This commit is contained in:
Lawrence Kesteloot
parent
491f8ef1b5
commit
a57bbe3c65
353
main.c
353
main.c
@ -9,11 +9,13 @@ unsigned char title_length = 9;
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#define T_HOME 0x80
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#define T_PRINT 0x81
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#define T_LIST 0x82
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// List of tokens. The token value is the index plus 0x80.
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static unsigned char *TOKEN[] = {
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"HOME",
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"PRINT",
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"LIST",
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};
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static int TOKEN_COUNT = sizeof(TOKEN)/sizeof(TOKEN[0]);
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@ -28,10 +30,18 @@ unsigned char g_input_buffer[40];
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int g_input_buffer_length = 0;
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// Compiled binary.
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char g_compiled[128];
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unsigned char g_compiled[128];
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int g_compiled_length = 0;
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void (*g_compiled_function)() = (void (*)()) g_compiled;
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// Stored program. Each line is:
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// - Two bytes for pointer to next line (or zero if none).
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// - Two bytes for line number.
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// - Program line.
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// - Nul.
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unsigned char g_program[1024];
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unsigned char *g_program_head;
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/**
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* Return the memory location of the cursor.
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*/
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@ -116,10 +126,147 @@ static void print(unsigned char *s) {
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}
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}
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/**
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* Print an unsigned integer.
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*/
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static void print_int(unsigned int i) {
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// Is this the best way to do this? I've seen it done backwards, where
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// digits are added to a buffer least significant digit first, then reversed,
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// but this seems faster.
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if (i >= 10000) {
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int r = i / 10000;
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print_char('0' + r);
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i -= r*10000;
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}
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if (i >= 1000) {
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int r = i / 1000;
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print_char('0' + r);
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i -= r*1000;
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}
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if (i >= 100) {
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int r = i / 100;
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print_char('0' + r);
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i -= r*100;
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}
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if (i >= 10) {
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int r = i / 10;
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print_char('0' + r);
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i -= r*10;
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}
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print_char('0' + i);
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}
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/**
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* Copy a memory buffer. Source and destination must not overlap.
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*/
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static void memcpy(unsigned char *dest, unsigned char *src, int count) {
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while (count-- > 0) {
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*dest++ = *src++;
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}
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}
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/**
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* Get the length of a nul-terminated string.
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*/
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static int strlen(unsigned char *s) {
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unsigned char *original = s;
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while (*s != '\0') {
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s += 1;
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}
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return s - original;
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}
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/**
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* Print the tokenized string, with tokens displayed as their full text.
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* Prints a newline at the end.
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*/
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static void print_detokenized(unsigned char *s) {
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while (*s != '\0') {
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if (*s >= 0x80) {
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print_char(' ');
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print(TOKEN[*s - 0x80]);
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print_char(' ');
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} else {
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print_char(*s);
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}
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s += 1;
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}
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print_char('\n');
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}
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/**
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* Get the pointer to the next line in the stored program. Returns 0
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* if we're at the end.
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*/
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static unsigned char *get_next_line(unsigned char *line) {
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return *((unsigned char **) line);
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}
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/**
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* Get the line number of a stored program line.
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*/
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static unsigned int get_line_number(unsigned char *line) {
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return *((unsigned int *) (line + 2));
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}
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/**
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* Return a pointer to the end of the program. This is one byte PAST the
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* last bytes in the program, which are three nuls. If there's no program
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* at all, returns the beginning of the program buffer. The "line" parameter is
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* an optional starting point, to use as an optimization instead of starting
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* from the beginning.
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*/
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static unsigned char *get_end_of_program(unsigned char *line) {
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if (g_program_head == 0) {
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// No program.
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return g_program;
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}
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if (line == 0) {
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line = g_program_head;
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}
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while (1) {
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unsigned char *next_line = get_next_line(line);
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if (next_line == 0) {
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// Last line of program.
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// Skip the line header (next pointer and line number).
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line += 4;
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// Skip the line itself and the three nuls.
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return line + strlen(line) + 3;
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}
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line = next_line;
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}
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}
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static void print_statement() {
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print("Hello world!\n");
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}
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/**
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* List the stored program.
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*/
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static void list_statement() {
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unsigned char *line = g_program_head;
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while (line != 0) {
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print_int(get_line_number(line));
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print_char(' ');
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print_detokenized(line + 4);
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// Next line.
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line = get_next_line(line);
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}
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}
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/**
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* If a starts with string b, returns the position in a after b. Else returns null.
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*/
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@ -232,21 +379,38 @@ static unsigned int tokenize(unsigned char *s) {
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}
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/**
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* Print the tokenized string, with tokens displayed as their full text.
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* Prints a line number first if it's not 0xFFFF. Prints a newline at the end.
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* Find the stored program line with the given line number. If there
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* is no stored program, returns null. If the line exists, returns
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* a pointer to it. If the line does not exist, returns a pointer to
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* the previous line.
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*/
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static void print_detokenized(unsigned int line_number, unsigned char *s) {
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while (*s != '\0') {
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if (*s >= 0x80) {
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print(TOKEN[*s - 0x80]);
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} else {
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print_char(*s);
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}
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static unsigned char *find_line(unsigned int line_number) {
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unsigned char *line;
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s += 1;
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if (g_program_head == 0) {
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// No program.
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return 0;
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}
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print_char('\n');
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line = g_program_head;
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while (1) {
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unsigned char *next_line;
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// See if we hit it.
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if (get_line_number(line) == line_number) {
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return line;
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}
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// See if we're at the end or if the next line is too far.
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next_line = get_next_line(line);
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if (next_line == 0 || get_line_number(next_line) > line_number) {
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return line;
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}
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// Go to next line.
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line = next_line;
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}
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}
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/**
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@ -262,85 +426,126 @@ static void process_input_buffer() {
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// Tokenize in-place.
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line_number = tokenize(g_input_buffer);
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if (line_number == 0xFFFF) {
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// Immediate mode.
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s = g_input_buffer;
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s = g_input_buffer;
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// Compile the line of BASIC.
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g_compiled_length = 0;
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// Compile the line of BASIC.
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g_compiled_length = 0;
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do {
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char error = 0;
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do {
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char error = 0;
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// Default to being done after one statement.
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done = 1;
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// Default to being done after one statement.
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done = 1;
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if (*s == '\0' || *s == ':') {
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// Empty statement.
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} else if (*s == T_HOME) {
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s += 1;
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add_call(home);
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} else if (*s == T_PRINT) {
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s += 1;
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// TODO: Parse expression.
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add_call(print_statement);
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} else {
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error = 1;
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}
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// Now we're at the end of our statement.
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if (!error) {
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if (*s == ':') {
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// Skip colon.
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if (*s == '\0' || *s == ':') {
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// Empty statement.
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} else if (*s == T_HOME) {
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s += 1;
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add_call(home);
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} else if (*s == T_PRINT) {
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s += 1;
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// Next statement.
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done = 0;
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} else if (*s != '\0') {
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// Junk at the end of the statement.
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// TODO: Parse expression.
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add_call(print_statement);
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} else if (*s == T_LIST) {
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s += 1;
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add_call(list_statement);
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} else {
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error = 1;
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}
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// Now we're at the end of our statement.
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if (!error) {
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if (*s == ':') {
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// Skip colon.
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s += 1;
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// Next statement.
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done = 0;
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} else if (*s != '\0') {
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// Junk at the end of the statement.
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error = 1;
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}
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}
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if (error) {
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add_call(syntax_error);
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}
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} while (!done);
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// Return from function.
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add_return();
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if (g_compiled_length > sizeof(g_compiled)) {
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// TODO: Check while adding bytes, not at the end.
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print("\n?Binary length exceeded");
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} else {
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// Call it.
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g_compiled_function();
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}
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if (error) {
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add_call(syntax_error);
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}
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} while (!done);
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// Return from function.
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add_return();
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if (g_compiled_length > sizeof(g_compiled)) {
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// TODO: Check while adding bytes, not at the end.
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print("\n?Binary length exceeded");
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} else {
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// Call it.
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g_compiled_function();
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unsigned char *line = find_line(line_number);
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// Stored mode. Add line to program.
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if (line == 0) {
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// New program. Just add line.
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g_program_head = g_program;
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// No next line.
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g_program[0] = 0;
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g_program[1] = 0;
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// Line number.
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g_program[2] = line_number & 0xFF;
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g_program[3] = line_number >> 8;
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// Include the three nuls.
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memcpy(g_program + 4, g_input_buffer, strlen(g_input_buffer) + 3);
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} else {
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// Program exists. Insert or replace line.
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if (get_line_number(line) == line_number) {
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// Line exists. Replace or delete line.
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if (g_input_buffer[0] == '\0') {
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// Empty line, delete old one.
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} else {
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// Replace line.
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}
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} else {
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// Line doesn't exist. Insert or append it.
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}
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}
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}
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}
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int main(void)
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{
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int i;
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int blink;
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// Initialize variables.
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g_program_head = 0;
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// Initialize UI.
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home();
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/*
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// Display the character set.
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for (i = 0; i < 256; i++) {
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volatile unsigned char *loc;
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// Fails with: unhandled instruction B2
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move_cursor(i % 16, i >> 4);
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// Works.
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// move_cursor(i & 0x0F, i >> 4);
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loc = cursor_pos();
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*loc = i;
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if (0) {
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int i;
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for (i = 0; i < 256; i++) {
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volatile unsigned char *loc;
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// Fails with: unhandled instruction B2
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move_cursor(i % 16, i >> 4);
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// Works.
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// move_cursor(i & 0x0F, i >> 4);
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loc = cursor_pos();
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*loc = i;
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}
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while(1);
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}
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while(1);
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*/
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// Title.
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// Print title.
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move_cursor((40 - title_length) / 2, 0);
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print(title);
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@ -348,19 +553,19 @@ int main(void)
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print("\n\n]");
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// Keyboard input.
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i = 0;
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blink = 0;
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g_input_buffer_length = 0;
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show_cursor();
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while(1) {
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// Blink cursor.
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i += 1;
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if (i == 3000) {
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blink += 1;
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if (blink == 3000) {
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if (g_showing_cursor) {
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hide_cursor();
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} else {
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show_cursor();
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}
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i = 0;
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blink = 0;
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}
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if(keyboard_test()) {
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