#!/bin/sh

# Display memory usage information on FreeBSD
# This function is a shell re-writting of the perl script:
##  freebsd-memory -- List Total System Memory Usage
##  Copyright (c) 2003-2004 Ralf S. Engelschall <rse@engelschall.com>
## http://www.cyberciti.biz/files/scripts/freebsd-memory.pl.txt

#   round the physical memory size to the next power of two which is
#   reasonable for memory cards. We do this by first determining the
#   guessed memory card size under the assumption that usual computer
#   hardware has an average of a maximally eight memory cards installed
#   and those are usually of equal size.

# Strict script
set -eu

mem_rounded () {
	mem_size=$1
	chip_size=1
	chip_guess=$(echo "$mem_size / 8 - 1" | bc)
	while [ $chip_guess != 0 ]; do
		chip_guess=$(echo "$chip_guess / 2" | bc)
		chip_size=$(echo "$chip_size * 2" | bc)
	done
	mem_round=$(echo "( $mem_size / $chip_size + 1 ) * $chip_size" | bc)
	echo $mem_round
	exit 0
}

free_memory () {
	#	determine the individual known information
	#	NOTICE: forget hw.usermem, it is just (hw.physmem - vm.stats.vm.v_wire_count).
	#	NOTICE: forget vm.stats.misc.zero_page_count, it is just the subset of
	#			vm.stats.vm.v_free_count which is already pre-zeroed.
	mem_phys=$(sysctl -n hw.physmem)
	set +e
	mem_hw=$(mem_rounded $mem_phys)
	set -e
	sysctl_pagesize=$(sysctl -n hw.pagesize)
	mem_all=$(echo "$(sysctl -n vm.stats.vm.v_page_count) * $sysctl_pagesize" | bc)
	mem_wire=$(echo "$(sysctl -n vm.stats.vm.v_wire_count) * $sysctl_pagesize" | bc)
	mem_active=$(echo "$(sysctl -n vm.stats.vm.v_active_count) * $sysctl_pagesize" | bc)
	mem_inactive=$(echo "$(sysctl -n vm.stats.vm.v_inactive_count) * $sysctl_pagesize" | bc)
	if sysctl -q vm.stats.vm.v_cache_count > /dev/null 2>&1 ; then
		mem_cache=$(echo "$(sysctl -n vm.stats.vm.v_cache_count) * $sysctl_pagesize" | bc)
		mem_laundry=""
	else
		mem_laundry=$(echo "$(sysctl -n vm.stats.vm.v_laundry_count) * $sysctl_pagesize" | bc)
		mem_cache=""
	fi
	mem_free=$(echo "$(sysctl -n vm.stats.vm.v_free_count) * $sysctl_pagesize" | bc)
	#	determine the individual unknown information
	if [ -n "${mem_cache}" ]; then
		mem_gap_vm=$(echo "$mem_all - ( $mem_wire + $mem_active + \
			$mem_inactive + $mem_cache + $mem_free )" | bc)
	else
		mem_gap_vm=$(echo "$mem_all - ( $mem_wire + $mem_active + \
			$mem_inactive + $mem_laundry + $mem_free )" | bc)
	fi
	mem_gap_sys=$(echo "$mem_phys - $mem_all" | bc)
	mem_gap_hw=$(echo "$mem_hw - $mem_phys" | bc)

	#	determine logical summary information
	mem_total=$mem_hw
	if [ -n "${mem_cache}" ]; then
		mem_avail=$(echo "$mem_inactive + $mem_cache + $mem_free" | bc)
	else
		mem_avail=$(echo "$mem_inactive + $mem_laundry + $mem_free" | bc)
	fi
	mem_used=$(echo "$mem_total - $mem_avail" | bc)

	# Swap
	swap_info=$(swapctl -sk)
	swap_total=$(echo "$(echo "$swap_info" | awk 'BEGIN {FS=" "} {print $2}' | bc) * 1024" | bc)
	swap_used=$(echo "$(echo "$swap_info" | awk 'BEGIN {FS=" "} {print $3}' | bc) * 1024" | bc)
	swap_avail=$(echo "$swap_total - $swap_used" | bc)

	#	print system results
	printf "SYSTEM MEMORY INFORMATION:\n"
	printf "mem_wire:      %12d (%7dMB) [%3d%%] %s\n" $mem_wire \
		$(echo "$mem_wire / ( 1024 * 1024 )" | bc) $(echo "$mem_wire \
		* 100 / $mem_all" | bc) "Wired: disabled for paging out"
	printf "mem_active:  + %12d (%7dMB) [%3d%%] %s\n" $mem_active \
		$(echo "$mem_active / ( 1024 * 1024 )" | bc) $(echo "$mem_active \
		* 100 / $mem_all" | bc) "Active: recently referenced"
	printf "mem_inactive:+ %12d (%7dMB) [%3d%%] %s\n" $mem_inactive \
		$(echo "$mem_inactive / ( 1024 * 1024 )" | bc) $(echo "$mem_inactive \
		* 100 / $mem_all" | bc) "Inactive: recently not referenced"
	if [ -n "${mem_cache}" ]; then
		printf "mem_cache:   + %12d (%7dMB) [%3d%%] %s\n" $mem_cache \
			$(echo "$mem_cache / ( 1024 * 1024 )" | bc) $(echo "$mem_cache \
			* 100 / $mem_all" | bc) "Cached: almost avail. for allocation"
	else
		printf "mem_laundry: + %12d (%7dMB) [%3d%%] %s\n" $mem_laundry \
			$(echo "$mem_laundry / ( 1024 * 1024 )" | bc) $(echo "$mem_laundry \
			* 100 / $mem_all" | bc) "Laundry: Pages eligible for laundering"
	fi
	printf "mem_free:    + %12d (%7dMB) [%3d%%] %s\n" $mem_free \
		$(echo "$mem_free / ( 1024 * 1024 )" | bc) $(echo "$mem_free \
		* 100 / $mem_all" | bc) "Free: fully available for allocation"
	printf "mem_gap_vm:  + %12d (%7dMB) [%3d%%] %s\n" $mem_gap_vm \
		$(echo "$mem_gap_vm / ( 1024 * 1024 )" | bc) $(echo "$mem_gap_vm \
		* 100 / $mem_all" | bc) "Memory gap: UNKNOWN"
	printf "______________ ____________ ___________ ______\n"
	printf "mem_all:     = %12d (%7dMB) [100%%] %s\n" $mem_all \
		$(echo "$mem_all / ( 1024 * 1024 )" | bc) "Total real memory managed"
	printf "mem_gap_sys: + %12d (%7dMB)	       %s\n" $mem_gap_sys \
		$(echo "$mem_gap_sys / ( 1024 * 1024 )" | bc) "Memory gap: Kernel?!"
	printf "______________ ____________ ___________\n"
	printf "mem_phys:    = %12d (%7dMB)	       %s\n" $mem_phys \
		$(echo "$mem_phys / ( 1024 * 1024 )" | bc) "Total real memory available"
	printf "mem_gap_hw:  + %12d (%7dMB)	       %s\n" $mem_gap_hw \
		$(echo "$mem_gap_hw / ( 1024 * 1024 )" | bc) "Memory gap: Segment Mappings?!"
	printf "______________ ____________ ___________\n"
	printf "mem_hw:      = %12d (%7dMB)        %s\n" $mem_hw \
		$(echo "$mem_hw / ( 1024 * 1024 )" | bc) "Total real memory installed"
	printf "\n"

	printf "SYSTEM MEMORY SUMMARY:\n"
	printf "mem_used:      %12d (%7dMB) [%3d%%] %s\n" $mem_used \
		$(echo "$mem_used / ( 1024 * 1024 )" | bc) $(echo "$mem_used \
		* 100 / $mem_total" | bc) "Logically used memory"
	printf "mem_avail:   + %12d (%7dMB) [%3d%%] %s\n" $mem_avail \
		$(echo "$mem_avail / ( 1024 * 1024 )" | bc) $(echo "$mem_avail \
		* 100 / $mem_total" | bc) "Logically available memory"
	printf "______________ ____________ __________ _______\n"
	printf "mem_total:   = %12d (%7dMB) [100%%] %s\n" $mem_total \
		$(echo "$mem_total / ( 1024 * 1024 )" | bc) "Logically total memory"
	printf "\n"
	if [ $swap_total != 0 ]; then
		printf "SWAP SUMMARY:\n"
		printf "swap_used:     %12d (%7dMB) [%3d%%] %s\n" $swap_used \
			$(echo "$swap_used / ( 1024 * 1024 )" | bc) $(echo "$swap_used \
			* 100 / $swap_total" | bc) "Used"
		printf "swap_avail:  + %12d (%7dMB) [%3d%%] %s\n" $swap_avail \
			$(echo "$swap_avail / ( 1024 * 1024 )" | bc) $(echo "$swap_avail \
			* 100 / $swap_total" | bc) "Available"
		printf "______________ ____________ ___________\n"
		printf "swap_total:  = %12d (%7dMB) [100%%] %s\n" $swap_total \
			$(echo "$swap_total / ( 1024 * 1024 )" | bc) "Total"
	fi
	exit 0
}

###################
## Main function ##
###################

free_memory