// Initialize hardware
void init()
{
// Disable the watchdog timer
*AT91C_WDTC_WDMR = AT91C_WDTC_WDDIS;
lcd_init();
keyboard_init();
lcd_print_int(0);
}
void print_all_ticks(void)
{
lcd_print_int(1,1,ticks[0]);
lcd_print_int(1,4,ticks[1]);
lcd_print_int(1,8,ticks[2]);
lcd_print_int(1,12,ticks[3]);
lcd_print_int(2,1,ticks[4]);
lcd_print_int(2,4,ticks[5]);
}
int main(){
init();
struct entry entry;
// User input loop
while (1){
// get either number and operation, or just an operation
keyboard_get_entry(&entry);
// Process the entry
// If there was a number in this entry, save to stack
if (entry.number != INT_MAX){
push(entry.number);
}
// If the action was the input key, or the stack is too small to do an operation
if (entry.operation == '\r' || stack_pointer < 2){
continue;
}
// Save the operands as the last 2 things on the stack
int a = get(stack_pointer - 2);
int b = get(stack_pointer - 1);
// Store the answer
int ans;
// Only used in division
int is_neg;
switch (entry.operation){
// Addition
case '+':
ans = a + b;
break;
// Subtraction
case '-':
ans = a - b;
break;
// Multiplication
case '*':
ans = a * b;
break;
// Division
// Our toolchain doesn't let us divide by a variable, so this code is nasty
case '/':
// If Kevin tries to divide by zero
if (b == 0){
taunt_user();
continue;
}
// Determine whether the result will be negative
is_neg = (a * b < 0);
// Take absolute value of operands
if (a < 0) a *= -1;
if (b < 0) b *= -1;
ans = 0;
// Calculate a / b
// Subtract a - b until a is zero, counting how many times we subtracted
while (a > 0){
a -= b;
ans++;
}
// If there is a remainder
if (a < 0){
// Always round down
ans--;
}
// Correct the sign of the result
if (is_neg){
ans *= -1;
}
break;
default:
break;
}
// Take the 2 operands off the stack
pop();
pop();
// Save answer to the end of the stack
push(ans);
lcd_print_int(ans);
}
return 0;
}
