#include "types.h"
#include "riscv.h"
#include "param.h"
#include "defs.h"
#include "memlayout.h"
#include "spinlock.h"
#include "proc.h"

uint64
sys_exit(void)
{
  int n;
  argint(0, &n);
  exit(n);
  return 0;  // not reached
}

uint64
sys_getpid(void)
{
  return myproc()->pid;
}

uint64
sys_fork(void)
{
  return fork();
}

uint64
sys_wait(void)
{
  uint64 p;
  argaddr(0, &p);
  return wait(p);
}

uint64
sys_sbrk(void)
{
  uint64 addr;
  int n;

  argint(0, &n);
  addr = myproc()->sz;
  if(growproc(n) < 0)
    return -1;
  return addr;
}

uint64
sys_sleep(void)
{
  int n;
  uint ticks0;


  argint(0, &n);
  acquire(&tickslock);
  ticks0 = ticks;
  while(ticks - ticks0 < n){
    if(killed(myproc())){
      release(&tickslock);
      return -1;
    }
    sleep(&ticks, &tickslock);
  }
  release(&tickslock);
  return 0;
}


#ifdef LAB_PGTBL
#define MAX_ABITS (64)

int
sys_pgaccess(void)
{
  char access_bits[MAX_ABITS / 8] = {0};
  uint64 base;
  int pages;
  uint64 mask;
  argaddr(0, &base); // void*
  argint(1, &pages); // int
  argaddr(2, &mask); // void*
  if (pages > MAX_ABITS) return -1;
  acquire(&myproc()->lock);
  for (int page = 0; page < pages; ++ page) {
    pte_t* pte = walk(myproc()->pagetable, base + (page << PGSHIFT), 0);
    if (*pte & PTE_A) {
      *pte &= ~PTE_A;
      access_bits[page / 8] |= 1 << (page & 0x7);
    }
  }
  release(&myproc()->lock);
  copyout(myproc()->pagetable, mask, access_bits, (pages & 0x7) ? (pages >> 3) + 1 : (pages >> 3));
  return 0;
}
#endif

uint64
sys_kill(void)
{
  int pid;

  argint(0, &pid);
  return kill(pid);
}

// return how many clock tick interrupts have occurred
// since start.
uint64
sys_uptime(void)
{
  uint xticks;

  acquire(&tickslock);
  xticks = ticks;
  release(&tickslock);
  return xticks;
}