Page 218 - The Unofficial Guide to Lego Mindstorms Robots

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int seek_enlightenment(int argc, char ∗∗argv) {
int baseline, current, loop_count, result;

seek_command = COMMAND_NONE;

// Get a baseline.
baseline = process_light(SENSOR_2);

loop_count = 0;

while(1) {
msleep(50); // Slow things down a little.
// Every so often, increase the baseline.
if (++loop_count == 5) {
if (baseline < 100) baseline++;
loop_count = 0;
}
current = process_light(SENSOR_2);
lcd_int(current ∗ 100 + baseline);
lcd_refresh();
// If the current value is somewhat less than the baseline…
if (current < (baseline - FUDGE)) {
// Set the baseline from the current value.
baseline = current;
// Search for something better.
if (sys_time % 2 == 0) seek_command = COMMAND_LEFT;
else seek_command = COMMAND_RIGHT;
result = wait_for_better(baseline, 1000);
if (result == -1) {
// If that timed out, search back the other direction.
if (seek_command == COMMAND_LEFT) seek_command = COMMAND_RIGHT;
else if (seek_command == COMMAND_RIGHT) seek_command =
COMMAND_LEFT;
result = wait_for_better(baseline, 2000);
if (result != -1) baseline = result;
// If there's nothing better, bail.
}
// Set the new baseline.
else baseline = result;
}
// Relinquish control.
seek_command = COMMAND_NONE;
}
return 0;
}

int cruise_command;

int cruise(int argc, char ∗∗argv) {
cruise_command = COMMAND_FORWARD;
while (1) sleep(1);
return 0;
}