README
Use git clone to download source.
Create tizen-image directory and unzip© the required image files. (As in proj0)
Enter cloned source directory and git switch to proj4 branch.
The directory structure should look like
dir_root/
------osfall2021-team1-proj4/
------------proj4.fs
------------qemu.sh
------------generate.sh (Automated kernel building and image movement script)
------------kernel/
------------------gps.c (Define syscall function & gps distance approxiation)
------------------gps_sec_arc_tan.h (table of arc_tan & cos for approximation)
------------------/include/linux
--------------------------------/syscall.h,fs.h,gps.h (add struct about gps data & declare function)
------------arch/arm64/include/asm
------------------unistd.h (Increased the number of syscalls)
------------------unistd32.h, syscall.h (Added syscall five locks)
------------------syscall.tbl (Added syscall set_rotation,locks,unlocks)
------------test/
------------------Makefile (Also mounts & moves binaries into the root image.)
------------------file_loc.c (As guide provides it outputs file location&google links)
------------------gpsupdate.c (update current location to certain coordinate)
------------------ext2/
----------------------ext2.h (add gps variable in fs)
----------------------file.c (add gps variable when creating file)
----------------------inode.c (load disk data to memory)
----------------------namei.c (set gps data when file creation)
------tizen-image/
------------.img files
------Building the OS------
Enter osfall2021-team1-proj4 and run ./generate.sh to build the kernel. (Requires root privileges)
------Building Test Files------
Enter osfall2021-team1-proj4/test and enter "make". (Requires root privileges)
MAKE ALSO COPIES ../proj4.fs INTO THE ROOT FILESYSTEM IMAGE IN ../../tizen-image
To run the VM, change directory to osfall2021-team1-proj4 and run ./qemu.sh (Requires root privileges)
After booting run the copied binary in the root user home directory.
Files under proj4.fs (All files empty.)
proj4/
snu_east - 37.452899, 126.9714, accuracy 20m
snu_west - 37.45317, 126.92649, accuracy 20m
snu_downtown/
snu_kyobo - 37.45933, 126.05056, accuracy 20m
snu_bogunso - 37.45904, 126.05081, accuracy 20m
snu_gwanjung - 37.45897, 126.95231, accuracy 20m
Test code usage
Please change fs to r/w and mount proj4.fs.
mount -o rw,remount /dev/mmcblk0p2 / -mount fs as rw
mkdir proj4 -create proj4 directory
mount -o loop -t ext2 /root/proj4.fs /root/proj4 -mount proj4.fs to proj4
./gpsupdate <lat_int> <lat_frac> <long_int> <long_frac> <accuracy>
and frac is alway 6 digit and less than 6 always fill up zero in higher bit for example
../gpsupdate 37 452899 126 971400 20 => 37.452899,126.971400
../gpsupdate 37 4528 126 9714 20 => 37.004528,126.009714
./file_loc <file_location>
output location info written in file for example
../file_loc snu_west
[ 67.830000] DEBUG: get_gps_location called.
[ 67.830292] DEBUG: get_gps_location complete.
latitude: 37.453170, longtitude: 126.026490, accuracy: 20 m
Google_link: www.google.com/maps/search/37.453170,126.926490
and if file is NOT accesible it will return -1m for example
[ 68.397041] DEBUG: get_gps_location called.
latitude: -1.000001, longtitude: -1.000001, accuracy: -1 m
Google_link: www.google.com/maps/search/-1.000001,-1.000001
Appoximation
proj4.fs contains two files which is 3.9km apart from each other
snu_east has 37.452899, 126.971400 coordinate
snu_west has 37.453170, 126.926490 coordinate
when approximation we needed to measure longtitude distance and latatitude distance
a) longtitude distance was calculated by multiplying longtitude angle diffrence with radius of earth
-assumption 1) ignore the altitude
-assumption 2) let arc of circle approximate to straight line
b) latitude distance was calculated by
get average latitude of two dot
multiply radius with longitude diff
-assumption 1) longitude diff does not make each radius too far from each other so that we can approximate two
dot as points on circle which has centen on the axis of rotation
-assumption 2) let arc of circle approximate to straight line
c) pythagoras
for this calculation instead of using root
we used arctan and cos with gps_sec_arc_tan.h
and since we have two distance diff we can calculate
x/cos(arctan(x/y))
which is same as (x^2 + y^2)^0.5
detaled pictures on ppt
Test code usage example
mount -o rw,remount /dev/mmcblk0p2 / -mount fs as rw
mkdir proj4 -create proj4 directory
mount -o loop -t ext2 /root/proj4.fs /root/proj4 -mount proj4.fs to proj4
cd proj4 -enter proj4
../gpsupdate 37 452899 126 971400 20 -set gps to certain location
touch snu_east -make file with coords 37.452899 126.9714, accuracy 20m
../gpsupdate 37 453170 126 926490 20 -new location
touch snu_west -make file with coords 37.45317 126.92649, accuracy 20m
cat snu_east -permission denied
cat snu_west -permission granted
../file_loc snu_west -return proper location&link
../file_loc snu_east -return -1m acc