From fec52b177f9babd0db2d0691a708a11af9269adc Mon Sep 17 00:00:00 2001
From: Mia <thatweeb@cumallover.me>
Date: Fri, 29 Oct 2021 13:59:05 -0400
Subject: [PATCH] wip LCG algo

---
 README    |  3 +++
 README.md |  3 ---
 ran       | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 3 deletions(-)
 create mode 100644 README
 delete mode 100644 README.md
 create mode 100644 ran

diff --git a/README b/README
new file mode 100644
index 0000000..6244f32
--- /dev/null
+++ b/README
@@ -0,0 +1,3 @@
+----
+# psh-prng
+-- an attempt at pure POSIX sh random number generation
\ No newline at end of file
diff --git a/README.md b/README.md
deleted file mode 100644
index 584b299..0000000
--- a/README.md
+++ /dev/null
@@ -1,3 +0,0 @@
-# psh-prng
-
-an attempt at pure POSIX sh random number generation
\ No newline at end of file
diff --git a/ran b/ran
new file mode 100644
index 0000000..5ef8071
--- /dev/null
+++ b/ran
@@ -0,0 +1,54 @@
+#!/bin/sh
+[ -c /dev/urandom ] && {
+  read -r seed < /dev/urandom # read a single line of urandom
+  seed=${#seed}
+} || { # otherwise generate a seed by counting stuff
+  n=0;
+  [ -x /bin/ ] && { # if we can access /bin count the files in it
+    for i in /bin/*; do
+      [ -f "$i" ] && : $((n+=1))
+    done
+  }
+  [ -x /tmp/ ] && {
+    for i in /tmp/*; do
+      [ -e "$i" ] && : $((n+=1))
+    done
+  }
+  [ -x /var/ ] && {
+    for i in /var/*; do
+      [ -e "$i" ] && : $((n+=1))
+    done
+  }
+  : $((n+=${#PWD})); : $((n+=${#0}))
+  seed="${n:-100}"
+}
+# $seed should now contain a number
+for i in 1 2 3 4 5; do # 5 times
+  [ ! "$((seed*seed))" -gt "$seed" ] && break # break if we have reached a max length num
+  seed=$((seed*seed))
+  seed="${seed#?}"; seed="${seed%?}" # use the middle-square method to generate a new seed
+done
+# LCG imp follows
+# generate a modulus (m) from the length of $seed and then detemine if its a prime
+m="${#seed}"; [ "$((m%2))" -eq 0 -o "$((m%3))" -eq 0 ] || : $((m+=1)) # if prime
+#             ^ if not a multiple of 2 or 3 expect the number to be prime and increase it by 1
+p=0 # $p is the next prime and can be determined using a while loop that adds 1 to it until it becomes a prime
+if [ "$((m%2))" -eq 0 ]; then # now determine the prime factors of $m
+  f=$((m/2)) # next prime is 3; 5
+  p=3 # we know the next prime
+  until [ ! "$((f%2))" -eq 0 -a ! "$((f%3))" -eq 0 ]; do
+    f=$((f/p))
+    : $((p+=1)); until [ ! "$((p%2))" -eq 0 -a ! "$((p%3))" -eq 0 ]; do
+      : $((P+=1))
+    done
+  done
+elif [ "$((m%3))" -eq 0 ]; then
+  f=$((m/3)) # next prime is 5; 7
+  p=5 
+  until [ ! "$((f%2))" -eq 0 -a ! "$((f%3))" -eq 0 ]; do
+    f=$((f/p))
+    : $((p+=1)); until [ ! "$((p%2))" -eq 0 -a ! "$((p%3))" -eq 0 ]; do
+      : $((p+=1))
+    done
+  done # until $f is prime do the above
+fi # $f is the prime factor of $m
\ No newline at end of file