#define _GNU_SOURCE
/*
    the idea of the scanner is that 
    you give it a memory address to watch
    and it reads from the address and if it
    matches the desired value, it sends
    a message to a controller

    ideally to detect a loading screen
    you would want to call the control function
    on a state change rather than every time
    the value matches
*/

//if linux
#include <stdlib.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <stdio.h>

//only watch one process at a time
static pid_t pid;

//control function
static void (*callback)(void);

int watch_memory(void *addr, int desired) {
    int values[1];
    struct iovec local[1];
    struct iovec remote[1];
    
    local[0].iov_base = values;
    local[0].iov_len = 1 * sizeof(int);

    remote[0].iov_base = (void *) addr;
    remote[0].iov_len = 1 * sizeof(int);
    
    int nread = process_vm_readv(pid, local, 4, remote, 4, 0);

    if (desired == values[0]) {
        //printf("%d %d\n", values[0], desired);
        callback();
    }

    return values[0];
}

void set_control_func(void (*c)(void)) {
    callback = c;
}

void set_pid(pid_t p) {
    pid = p;
}