four kinds of hash

1. corned beef

2. smoke

3. non-security hash - java.lang.String hashcode, FNV
   e.g. 16-bit hash, array size 65536, h=hash(string), a[h] = list of strings
   n-bit hash, P(collison)>=0.5 with approx sqrt(2**n) = 2**(n/2) input strings

4. secure hash algorithm or message digest, P(collision) ~= 0, one-way function

---

$ make
gcc -std=c11 -pedantic -Wall -DPART1 -o fork1 fork.c
gcc -std=c11 -pedantic -Wall -o fork2 fork.c
gcc -std=c11 -pedantic -Wall -DPART1 -o pthread1 pthread.c -pthread
gcc -std=c11 -pedantic -Wall -o pthread2 pthread.c -pthread

$ ./fork1
parent 22873 1
child 22874 1
child 22874 2
parent 22873 2
child 22874 3
child 22874 4
parent 22873 3
child 22874 5
-rw-r--r-- 1 perry perry 336 Nov 29 05:30 Makefile
parent 22873 4
parent 22873 5

$ ./pthread1
main 22886 1
f 22886 2
f 22886 3
main 22886 4
f 22886 5
f 22886 6
main 22886 7
f 22886 8
main 22886 9
main 22886 10

$ ./fork2
parent got: hi from child
s = 16896, exit = 66

$ ./pthread2
main got: hi from f
*v = 99

$ make clean
rm -f a.out core fork1 fork2 pthread1 pthread2

$