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Better stored program linked list management.

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This commit is contained in:
Lawrence Kesteloot 2018-08-01 14:58:29 -07:00
parent a324d8814b
commit ca49e6e511
1 changed files with 76 additions and 78 deletions
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154
main.c
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@ -40,7 +40,6 @@ void (*g_compiled_function)() = (void (*)()) g_compiled;
// - Program line.
// - Nul.
uint8_t g_program[1024];
uint8_t *g_program_head;
/**
* Return the memory location of the cursor.
@ -127,7 +126,7 @@ static void print(uint8_t *s) {
}
/**
* Print an uint16_teger.
* Print an unsigned integer.
*/
static void print_int(uint16_t i) {
// Is this the best way to do this? I've seen it done backwards, where
@ -157,11 +156,22 @@ static void print_int(uint16_t i) {
}
/**
* Copy a memory buffer. Source and destination must not overlap.
* Copy a memory buffer. Source and destination may overlap.
*/
static void memcpy(uint8_t *dest, uint8_t *src, int16_t count) {
while (count-- > 0) {
*dest++ = *src++;
static void memmove(uint8_t *dest, uint8_t *src, uint16_t count) {
// See if we overlap.
if (dest > src && dest < src + count) {
// Overlapping with src before dest, we have to copy backward.
dest += count;
src += count;
while (count-- > 0) {
*--dest = *--src;
}
} else {
// No overlap, or dest before src, which is fine.
while (count-- > 0) {
*dest++ = *src++;
}
}
}
@ -215,36 +225,24 @@ static uint16_t get_line_number(uint8_t *line) {
/**
* Return a pointer to the end of the program. This is one byte PAST the
* last bytes in the program, which are three nuls. If there's no program
* at all, returns the beginning of the program buffer. The "line" parameter is
* last bytes in the program, which are two nuls. The "line" parameter is
* an optional starting point, to use as an optimization instead of starting
* from the beginning.
*/
static uint8_t *get_end_of_program(uint8_t *line) {
if (g_program_head == 0) {
// No program.
return g_program;
}
uint8_t *next_line;
if (line == 0) {
line = g_program_head;
// Start at the beginning if not specified.
line = g_program;
}
while (1) {
uint8_t *next_line = get_next_line(line);
if (next_line == 0) {
// Last line of program.
// Skip the line header (next pointer and line number).
line += 4;
// Skip the line itself and the three nuls.
return line + strlen(line) + 3;
}
while ((next_line = get_next_line(line)) != 0) {
line = next_line;
}
// Skip the null "next" pointer.
return line + 2;
}
static void print_statement() {
@ -255,15 +253,15 @@ static void print_statement() {
* List the stored program.
*/
static void list_statement() {
uint8_t *line = g_program_head;
uint8_t *line = g_program;
uint8_t *next_line;
while (line != 0) {
while ((next_line = get_next_line(line)) != 0) {
print_int(get_line_number(line));
print_char(' ');
print_detokenized(line + 4);
// Next line.
line = get_next_line(line);
line = next_line;
}
}
@ -379,38 +377,23 @@ static uint16_t tokenize(uint8_t *s) {
}
/**
* Find the stored program line with the given line number. If there
* is no stored program, returns null. If the line exists, returns
* a pointer to it. If the line does not exist, returns a pointer to
* the previous line.
* Find the stored program line with the given line number. If the line does
* not exist, returns a pointer to the location where it should be inserted.
*/
static uint8_t *find_line(uint16_t line_number) {
uint8_t *line;
uint8_t *line = g_program;
uint8_t *next_line;
if (g_program_head == 0) {
// No program.
return 0;
}
line = g_program_head;
while (1) {
uint8_t *next_line;
// See if we hit it.
if (get_line_number(line) == line_number) {
return line;
while ((next_line = get_next_line(line)) != 0) {
// See if we hit it or just blew past it.
if (get_line_number(line) >= line_number) {
break;
}
// See if we're at the end or if the next line is too far.
next_line = get_next_line(line);
if (next_line == 0 || get_line_number(next_line) > line_number) {
return line;
}
// Go to next line.
line = next_line;
}
return line;
}
/**
@ -486,35 +469,49 @@ static void process_input_buffer() {
g_compiled_function();
}
} else {
uint8_t *line = find_line(line_number);
// Stored mode. Add line to program.
if (line == 0) {
// New program. Just add line.
g_program_head = g_program;
// No next line.
g_program[0] = 0;
g_program[1] = 0;
// Return line to replace or delete, or location to insert new line.
uint8_t *line = find_line(line_number);
uint8_t *next_line = get_next_line(line);
if (next_line == 0 || get_line_number(line) != line_number) {
// Didn't find line. Insert it here.
uint8_t *end_of_program = get_end_of_program(line);
// Next pointer, line number, line, and nul.
int buffer_length = strlen(g_input_buffer);
int line_length = 4 + buffer_length + 1;
// Shift rest of program over.
memmove(line + line_length, line, end_of_program - line);
// Next line. Point to yourself initially, we'll adjust below.
*((uint8_t **) line) = line;
// Line number.
g_program[2] = line_number & 0xFF;
g_program[3] = line_number >> 8;
*((uint16_t *) (line + 2)) = line_number;
// Include the three nuls.
memcpy(g_program + 4, g_input_buffer, strlen(g_input_buffer) + 3);
// Buffer and nul.
memmove(line + 4, g_input_buffer, buffer_length + 1);
// Adjust all the next pointers.
while ((next_line = get_next_line(line)) != 0) {
// Adjust by the amount we inserted.
next_line += line_length;
*((uint8_t **) line) = next_line;
line = next_line;
}
} else {
// Program exists. Insert or replace line.
// Found line.
if (get_line_number(line) == line_number) {
// Line exists. Replace or delete line.
if (g_input_buffer[0] == '\0') {
// Empty line, delete old one.
} else {
// Replace line.
}
if (g_input_buffer[0] == '\0') {
// Empty line, delete old one.
print("Deletion not handled\n");
} else {
// Line doesn't exist. Insert or append it.
// Replace line.
print("Replacement not handled\n");
}
}
}
@ -524,8 +521,9 @@ int16_t main(void)
{
int16_t blink;
// Initialize variables.
g_program_head = 0;
// Blank program.
g_program[0] = '\0';
g_program[1] = '\0';
// Initialize UI.
home();