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Can print single integer.

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This commit is contained in:
Lawrence Kesteloot 2018-08-01 23:29:37 -07:00
parent e2199b66fe
commit b9b4b6fded
1 changed files with 60 additions and 14 deletions
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74
main.c
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@ -7,6 +7,13 @@ uint8_t title_length = 9;
#define SCREEN_WIDTH 40
#define SCREEN_STRIDE (3*SCREEN_WIDTH + 8)
// 6502 instructions.
#define I_JSR 0x20
#define I_RTS 0x60
#define I_LDX 0xA2
#define I_LDA 0xA9
// Tokens.
#define T_HOME 0x80
#define T_PRINT 0x81
#define T_LIST 0x82
@ -245,8 +252,11 @@ static uint8_t *get_end_of_program(uint8_t *line) {
return line + 2;
}
static void print_statement() {
print("Hello world!\n");
/**
* Print a single newline.
*/
static void print_newline() {
print_char('\n');
}
/**
@ -294,10 +304,10 @@ static void syntax_error() {
/**
* Add a function call to the compiled buffer.
*/
static void add_call(void (*function)(void)) {
static void add_call(void *function) {
uint16_t addr = (int16_t) function;
g_compiled[g_compiled_length++] = 0x20; // JSR
g_compiled[g_compiled_length++] = I_JSR;
g_compiled[g_compiled_length++] = addr & 0xFF;
g_compiled[g_compiled_length++] = addr >> 8;
}
@ -306,13 +316,14 @@ static void add_call(void (*function)(void)) {
* Add a function return to the compiled buffer.
*/
static void add_return() {
g_compiled[g_compiled_length++] = 0x60; // RTS
g_compiled[g_compiled_length++] = I_RTS;
}
/**
* Advance s over whitespace, which is just a space, returning
* the new pointer.
*/
/* Unused.
static uint8_t *skip_whitespace(uint8_t *s) {
while (*s == ' ') {
s += 1;
@ -320,6 +331,26 @@ static uint8_t *skip_whitespace(uint8_t *s) {
return s;
}
*/
/**
* Parse an unsigned integer, returning the value and moving the pointer
* past the end of the number. The pointer must already be at the beginning
* of the number.
*/
static uint16_t parse_uint16(uint8_t **s_ptr) {
uint16_t value = 0;
uint8_t *s = *s_ptr;
while (*s >= '0' && *s <= '9') {
value = value*10 + (*s - '0');
s += 1;
}
*s_ptr = s;
return value;
}
/**
* Tokenize a string in place. Returns (and removes) any line number, or 0xFFFF
@ -331,12 +362,7 @@ static uint16_t tokenize(uint8_t *s) {
// Parse optional line number.
if (*s >= '0' && *s <= '9') {
line_number = 0;
while (*s >= '0' && *s <= '9') {
line_number = line_number*10 + (*s - '0');
s += 1;
}
line_number = parse_uint16(&s);
} else {
line_number = 0xFFFF;
}
@ -427,8 +453,17 @@ static void process_input_buffer() {
} else if (*s == T_PRINT) {
s += 1;
// TODO: Parse expression.
add_call(print_statement);
if (*s >= '0' && *s <= '9') {
// Parse expression.
uint16_t value = parse_uint16(&s);
g_compiled[g_compiled_length++] = I_LDX;
g_compiled[g_compiled_length++] = value >> 8;
g_compiled[g_compiled_length++] = I_LDA;
g_compiled[g_compiled_length++] = value & 0xFF;
add_call(print_int);
}
add_call(print_newline);
} else if (*s == T_LIST) {
s += 1;
add_call(list_statement);
@ -531,6 +566,15 @@ int16_t main(void)
{
int16_t blink;
/*
int16_t i, j, k;
i = 2;
j = 3;
k = 4;
i = i*j;
*/
// Blank program.
g_program[0] = '\0';
g_program[1] = '\0';
@ -539,7 +583,8 @@ int16_t main(void)
home();
// Display the character set.
if (0) {
/*
if (1) {
int16_t i;
for (i = 0; i < 256; i++) {
volatile uint8_t *loc;
@ -552,6 +597,7 @@ int16_t main(void)
}
while(1);
}
*/
// Print title.
move_cursor((40 - title_length) / 2, 0);