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apple2a
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More robust parsing of variable name.

This commit is contained in:
Lawrence Kesteloot 2018-08-03 13:31:31 -07:00
parent 0d579ce354
commit d9594ce3ad
1 changed files with 14 additions and 7 deletions
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21
main.c
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@ -45,6 +45,13 @@ uint8_t title_length = 9;
// Variable for "No more space for variables".
#define OUT_OF_VARIABLE_SPACE 0xFF
// Test for whether a character is a digit.
#define IS_DIGIT(ch) ((ch) >= '0' && (ch) <= '9')
// Test for first and subsequent variable name letters.
#define IS_FIRST_VARIABLE_LETTER(ch) ((ch) >= 'A' && (ch) <= 'Z')
#define IS_SUBSEQUENT_VARIABLE_LETTER(ch) (IS_FIRST_VARIABLE_LETTER(ch) || IS_DIGIT(ch))
// List of tokens. The token value is the index plus 0x80.
static uint8_t *TOKEN[] = {
"HOME",
@ -209,7 +216,7 @@ static uint16_t parse_uint16(uint8_t **s_ptr) {
uint16_t value = 0;
uint8_t *s = *s_ptr;
while (*s >= '0' && *s <= '9') {
while (IS_DIGIT(*s)) {
value = value*10 + (*s - '0');
s += 1;
}
@ -244,13 +251,13 @@ static uint8_t find_variable(uint8_t **buffer) {
// Pull out the variable name.
name[0] = *s++;
if (*s != 0 && (*s & 0x80) == 0) {
if (IS_SUBSEQUENT_VARIABLE_LETTER(*s)) {
name[1] = *s++;
} else {
name[1] = 0;
}
// Skip rest of name.
while (*s != 0 && (*s & 0x80) == 0) {
while (IS_SUBSEQUENT_VARIABLE_LETTER(*s)) {
s++;
}
@ -289,7 +296,7 @@ static uint8_t *compile_expression(uint8_t *s) {
char have_value_in_ax = 0;
while (1) {
if (*s >= '0' && *s <= '9') {
if (IS_DIGIT(*s)) {
// Parse number.
uint16_t value;
@ -301,7 +308,7 @@ static uint8_t *compile_expression(uint8_t *s) {
value = parse_uint16(&s);
compile_load_ax(value);
have_value_in_ax = 1;
} else if (*s >= 'A' && *s <= 'Z') {
} else if (IS_FIRST_VARIABLE_LETTER(*s)) {
// Variable reference.
uint8_t var = find_variable(&s);
@ -348,7 +355,7 @@ static uint16_t tokenize(uint8_t *s) {
int16_t line_number;
// Parse optional line number.
if (*s >= '0' && *s <= '9') {
if (IS_DIGIT(*s)) {
line_number = parse_uint16(&s);
} else {
line_number = INVALID_LINE_NUMBER;
@ -428,7 +435,7 @@ static void compile_buffer(uint8_t *buffer, uint16_t line_number) {
if (*s == '\0' || *s == ':') {
// Empty statement. We skip the colon below.
} else if (*s >= 'A' && *s <= 'Z') {
} else if (IS_FIRST_VARIABLE_LETTER(*s)) {
// Must be variable assignment.
uint8_t var = find_variable(&s);
if (var == OUT_OF_VARIABLE_SPACE) {