From 6095a746c3dce24f30fb3a4faa7f20149675288a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Tj=C3=A4der?= <henrik@tjaders.com>
Date: Thu, 9 Nov 2017 18:58:52 +0100
Subject: [PATCH] Now codgen works
---
src/main.rs | 85 +++++++++++++++++++++++++++++++++--------------------
1 file changed, 53 insertions(+), 32 deletions(-)
diff --git a/src/main.rs b/src/main.rs
index 62de534..6171a82 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -145,45 +145,66 @@ static CODED: [u32; 132] =
///
/// Count the number of zeroes
///
-fn count_zero(num: u32) -> u32 {
+fn count_zero(mut num: u32) -> u32 {
- let mut count_zero = 0;
- let mut count_one = 0;
+ let mut n = 32;
- for x in 0..32 {
- if num % 2 == 0 {
- count_zero += 1;
- } else {
- count_one += 1;
+ while num != 0 {
+ if num & 1u32 == 1u32 {
+ n -= 1;
}
- num << 1;
+ num >>= 1;
}
- count_zero ^ count_one
+ n
}
///
/// Modify the seed for decoding
///
+///
+///FUNCTION codgen(): UNSIGNED INTEGER;
+/// LOCAL SIGNED INTEGER n;
+/// LOCAL UNSIGNED INTEGER x, y;
+/// BEGIN
+/// n := [count the number of 0's in word "seed"];
+/// x := [rotate "seed" left by 30 bits];
+/// y := [shift "seed" right-ARITHMETIC by 6 bits];
+/// seed := x XOR y XOR n;
+/// RETURN( seed XOR 0x464b713e );
+/// END;
fn codgen(seed: &mut u32) -> u32 {
let n: u32;
let (x, y): (u32, u32);
- n = count_zero(*seed);
+ let local_seed: u32 = seed.clone();
+
+
+ // Send away copy of seed
+ //n = count_zero(local_seed);
+ n = local_seed.count_zeros();
+
+ println!("Number of zeroes: {}", n);
- println!("Seed:\n{:b}", *seed);
+ //println!("Seed:\n{:b}", local_seed);
// Inte OK än
- x = seed.rotate_left(2);
- println!("{:b}", x);
+ x = local_seed.rotate_left(30);
+
+ // Stolen from K & H
+ //x = local_seed << 30 | ((local_seed>> 2) & 0x3FFFFFFF);
+
+ //println!("{:b}", x);
// Fungerade fint
- y = *seed >> 6;
+ // Shift 6 to the right arithmetic
+ // Needs to be i32 to be arithmetic, testing wrapping_shr
+ y = ((local_seed as i32) >> 6) as u32;
+ //y = local_seed.wrapping_shr(6);
- *seed = x ^ y ^ n;
+ *seed = (x ^ y ^ n) as u32;
(*seed) ^ 0x464b713e
-
}
///
@@ -191,7 +212,6 @@ fn codgen(seed: &mut u32) -> u32 {
///
fn decode(coded: &[u32], plain: &mut[u8], seed: &mut u32) -> u32 {
-
let x = 3;
x
@@ -204,28 +224,29 @@ fn main() {
let mut seed = 0x3e944b9f;
//decode(&CODED, unsafe { &mut PLAIN }, &mut seed);
- //
- codgen(&mut seed);
- println!("Ran codgen, new seed: {:x}", seed);
+ let mut locseed;
+
+ locseed = codgen(&mut seed);
+ assert_eq!(locseed, 0x891432f9);
+ println!("Ran codgen, new seed: {:x}", locseed);
+ locseed = codgen(&mut seed);
+ println!("Ran codgen, new seed: {:x}", locseed);
+ locseed = codgen(&mut seed);
+ println!("Ran codgen, new seed: {:x}", locseed);
+ locseed = codgen(&mut seed);
+ println!("Ran codgen, new seed: {:x}", locseed);
+ locseed = codgen(&mut seed);
+ assert_eq!(locseed, 0xce83d1b8);
+ println!("Ran codgen, new seed: {:x}", locseed);
}
+
/*
# Group 1's Codeword Generator Subroutine (pseudocode)
# (remember: "seed" is a global variable, UNSIGNED INTEGER;
# you may implement local variables in registers or on the stack;
# result returned in v0; preserve all except t regs)
-#
-# FUNCTION codgen(): UNSIGNED INTEGER;
-# LOCAL SIGNED INTEGER n;
-# LOCAL UNSIGNED INTEGER x, y;
-# BEGIN
-# n := [count the number of 0's in word "seed"];
-# x := [rotate "seed" left by 30 bits];
-# y := [shift "seed" right-ARITHMETIC by 6 bits];
-# seed := x XOR y XOR n;
-# RETURN( seed XOR 0x464b713e );
-# END;
#
# hint: if "seed" is initialized to 0x3e944b9f,
# the first five calls will generate these values:
--
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