/*------------------------------------------------------*
 | Author: Maurizio Loreti, aka MLO or (HAM) I3NOO      |
 | Work:   University of Padova - Department of Physics |
 |         Via F. Marzolo, 8 - 35131 PADOVA - Italy     |
 | Phone:  ++39(49) 827-7216     FAX: ++39(49) 827-7102 |
 | EMail:  loreti@padova.infn.it                        |
 | WWW:    http://wwwcdf.pd.infn.it/~loreti/mlo.html    |
 *------------------------------------------------------*

 Tries to list available memory on several architectures;
 Needs -lmach to be linked under Digital Unix.

 *------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/utsname.h>

static int memory(void);

int main()
{
  struct utsname un;

  if (uname(&un) >= 0) {
    fprintf(stdout, "RAM on machine \"%s\", running %s %s :\n",
	    un.nodename, un.sysname, un.release);
  }
  return memory();
}

#ifdef __sun__
static int memory(void)
{
  long npag;                    /* Number of physical pages */
  long nbyt;                    /* Numper of bytes per page */
  int nmeg;                     /* Number of Megabytes on the system */
  double x;

  npag = sysconf(_SC_PHYS_PAGES);
  nbyt = sysconf(_SC_PAGESIZE);
  x = npag;
  x *= nbyt;
  x /= 1024.0;
  x /= 1024.0;
  nmeg = x + 0.5;
  fprintf(stdout,
          "%ld Pages, %ld Bytes each - %d MBytes total.\n",
          npag, nbyt, nmeg);

  return EXIT_SUCCESS;
}
#endif /* __sun__ */

#ifdef __linux__
#include <ctype.h>
#include <fcntl.h>
#define BUFFER_LEN 128

static int memory(void)
{
  int retVal = EXIT_FAILURE;
  int fd;

  if ((fd = open("/proc/meminfo", O_RDONLY)) < 0) {
    fputs("Couldn't open /proc/meminfo\n", stderr);
    perror("open");
  } else {
    char buffer[BUFFER_LEN];
    size_t len;

    if ((len = read(fd, buffer, sizeof(buffer)-1)) < 0) {
      fputs("Error read from /proc/meminfo\n", stderr);
      perror("read");
    } else {
      const char *pc = buffer;
      char *end;
      unsigned long total, used, free;

/* buffer[len]='\0'; puts(buffer); */

      while (*pc++ != '\n') {}
      while (!isspace((unsigned char) *pc)) pc++;
      total = strtoul(pc, &end, 0) / 1024;
      used = strtoul(end, &end, 0) / 1024;
      free = strtoul(end, &end, 0) / 1024;
      fprintf(stdout,
              "Total memory: %lu kBytes (%lu kBytes used, %lu kBytes free)\n",
              total, used, free);
      retVal = EXIT_SUCCESS;
    }
    close(fd);
  }
  return retVal;
}
#endif /* __linux__ */

#ifdef __osf__
#include <mach.h>
#include <mach/vm_statistics.h>
#define LOG1024 10              /* log base 2 of 1024 */

static int memory(void)
{
  int pagesize;
  int pageshift;                /* log base 2 of the pagesize */
  long active, total, free;
  vm_statistics_data_t vmstats;

  pagesize = getpagesize();
  for (pageshift = 0;   pagesize > 1;   pageshift++,  pagesize >>= 1) {}
  pageshift -= LOG1024;

  (void) vm_statistics(task_self(), &vmstats);
  total = active = vmstats.active_count << pageshift;
  total += (free = vmstats.free_count << pageshift);
  total += (vmstats.inactive_count + vmstats.wire_count) << pageshift;
  fprintf(stdout,
          "%ld active, %ld free, %ld total (in kBytes).\n",
          active, free, total);
  return EXIT_SUCCESS;
}
#endif /* __osf__ */