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#include <stdint.h>
#include "bignum.h"
char would_overflow(unsigned long value, unsigned long amount) {
return ((UINT32_MAX - amount) <= value);
}
char bank_withdraw(long amount) {
bignum(bigamt);
if(amount < 0) {
/* can't withdraw all, if too much in bank */
if(big_cmp(&bank, B_MAXLONG) == 1)
return 0;
big_copy(&bigamt, &bank);
big_to_ulong(&bigamt, &amount);
}
if(would_overflow(cash, amount)) return 0;
cash += amount;
ulong_to_big(&amount, &bigamt);
big_sub(&bank, &bank, &bigamt);
return 1;
}
void bank_deposit(long amount) {
bignum bigamt;
if(amount < 0) amount = cash;
cash -= amount;
ulong_to_big(&amount, &bigamt);
big_add(&bank, &bank, &bigamt);
}
void bank_interest(void) {
big_mul(&bank, &bank, &interest_rate);
}
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