#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/fcntl.h>

#include "pagemap.h"

#define HASH_SHIFT	13
#define HASH_MASK	((1 << HASH_SHIFT) - 1)
#define HASH_KEY(flags)	(flags & HASH_MASK)

static unsigned long	page_count[1 << HASH_SHIFT];
static uint64_t 	page_flags[1 << HASH_SHIFT];

int hash_index(uint64_t flags)
{
	int i;
	int k = HASH_KEY(flags);

	if (!flags)
		return 0;

	for (i = 1; i < ARRAY_SIZE(page_count); i++, k++) {
		if (!k || k >= ARRAY_SIZE(page_count))
			k = 1;
		if (page_flags[k] == 0) {
			page_flags[k] = flags;
			return k;
		}
		if (page_flags[k] == flags)
			return k;
	}

	exit(1); /* die hard on full hash table */
}

char *page_flag_name(uint64_t flags)
{
	int i, j;
	int bit;
	static char buf[65];

	for (i = 0, j = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		bit = (flags >> i) & 1;
		if (!page_flag_names[i]) {
			if (bit)
				fprintf(stderr, "unkown flag bit %d\n", i);
			continue;
		}
		buf[j++] = bit ? page_flag_names[i][0] : '_';
	}

	return buf;
}

char *page_flag_longname(uint64_t flags)
{
	int i, n;
	static char buf[1024];

	for (i = 0, n = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		if (!page_flag_names[i])
			continue;
		if ((flags >> i) & 1)
		       n += snprintf(buf + n, sizeof(buf) - n, "%s,",
				       page_flag_names[i] + 2);
	}
	if (n)
		n--;
	buf[n] = '\0';

	return buf;
}

static unsigned long nr_pages;
static uint64_t kpageflags[KPF_BYTES * (1<<20)];

unsigned long collect_page_count()
{
	unsigned long n;
	unsigned long i;
	uint64_t flags;
	int fd;

	fd = open(PROC_KPAGEFLAGS, O_RDONLY);
	if (fd < 0) {
		perror(PROC_KPAGEFLAGS);
		exit(1);
	}

	while (1) {
		n = read(fd, kpageflags, sizeof(kpageflags));
		if (n == 0)
			break;
		if (n < 0) {
			perror(PROC_KPAGEFLAGS);
			exit(2);
		}
		if (n % KPF_BYTES != 0) {
			fprintf(stderr, "partial read: %lu bytes\n", n);
			exit(3);
		}
		n = n / KPF_BYTES;

		for (i = 0; i < n; i++) {
			flags = kpageflags[i];
			page_count[hash_index(flags)]++;
		}
		nr_pages += n;
	}

	close(fd);
}

void show_page_count()
{
	int i;

	printf("         flags\tpage-count       MB"
		"  symbolic-flags\t\t\tlong-symbolic-flags\n");

	for (i = 0; i < ARRAY_SIZE(page_count); i++) {
		if (page_count[i])
			printf("0x%012lx\t%10lu %8lu  %s\t%s\n",
				page_flags[i],
				page_count[i],
				pages2mb(page_count[i]),
				page_flag_name(page_flags[i]),
				page_flag_longname(page_flags[i]));
	}

	printf("         total\t%10lu %8lu\n",
			nr_pages, pages2mb(nr_pages));
}

int main(int argc, char *argv[])
{
	collect_page_count();
	show_page_count();
	return 0;
}