/*  $Id: get_mem.c,v 1.4 2017/02/26 16:03:48 bch Exp $
 * Adapted: get memory usage on OpenBSD
 * Author: Christian Barthel <bch@vcs.onfire.org>
 *
 * get memory usage, from get_load.c derived
 *
 * Author:  Hans-Helmut Buehmann 20. Jan. 1996
 * 
 * Modified for more recent kernels Helmut Geyer Oct. 1996
 */

#include <sys/param.h>	/* DEV_BSIZE MAXCOMLEN PZERO */
#include <sys/sysctl.h>
#include <sys/swap.h>
#include <sys/mount.h>
#include <sys/proc.h>

#include <unistd.h>

#include <X11/Xos.h>
#include <X11/Intrinsic.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>
#include "MemStripChart.h"

static int pageshift = -1; 
#define pagetok(size) ((size) << pageshift)
#define LOG1024 10 

static double allmem_kb = 0; 

static void initPageShift(void)
{
	int pagesize = getpagesize();
	pageshift = 0;
	while (pagesize > 1) {
		pageshift++;
		pagesize >>= 1;
	}
	pageshift -= LOG1024;
}

static double getSwapFrac() 
{
	struct swapent *swdev;
	int used, total, nswap, rnswap, i;

	nswap = swapctl(SWAP_NSWAP, 0, 0);
	if (nswap == 0)
		return 0;

	swdev = calloc(nswap, sizeof(*swdev));
	if (swdev == NULL)
		return 0;

	rnswap = swapctl(SWAP_STATS, swdev, nswap);
	if (rnswap == -1) {
		free(swdev);
		return 0;
	}

	/* if rnswap != nswap, then what? */

	/* Total things up */
	total = used = 0;
	for (i = 0; i < nswap; i++) {
		if (swdev[i].se_flags & SWF_ENABLE) {
			used += (swdev[i].se_inuse / (1024 / DEV_BSIZE));
			total += (swdev[i].se_nblks / (1024 / DEV_BSIZE));
		}
	}
	free(swdev);
	return (double)used/total;
}

void GetMemLoadPoint(Widget w, caddr_t closure, caddr_t call_data)	
{
	static int bcstats_mib[] = {CTL_VFS, VFS_GENERIC, VFS_BCACHESTAT};
	static int uvmexp_mib[] = {CTL_VM, VM_UVMEXP};
	MemStripChartCallbackData ret;
	struct uvmexp uvmexp;
	struct bcachestats bcstats;
	size_t size; 
	
	if (pageshift < 0) 
		initPageShift(); 

	size = sizeof(uvmexp);
	if (sysctl(uvmexp_mib, 2, &uvmexp, &size, NULL, 0) < 0) {
		warn("sysctl failed");
		bzero(&uvmexp, sizeof(uvmexp));
	}
	size = sizeof(bcstats);
	if (sysctl(bcstats_mib, 3, &bcstats, &size, NULL, 0) < 0) {
		warn("sysctl failed");
		bzero(&bcstats, sizeof(bcstats));
	}


	allmem_kb = pagetok(uvmexp.npages); 
	ret.cached = pagetok(bcstats.numbufpages) / allmem_kb;
	ret.free = pagetok(uvmexp.free) / allmem_kb;
	ret.buffer = 0;
	ret.code = (1 - ret.cached - ret.free);
	ret.swap = getSwapFrac();

#ifdef DEBUG
	printf("%lf  %lf %lf  %lf %lf\n", allmem_kb, ret.code, ret.cached, ret.free, ret.swap);
#endif
	
	memcpy(call_data, &ret, sizeof(MemStripChartCallbackData));
}