From cdaa8f78cabd96a2e27b6fc35ef7c317ad49264c Mon Sep 17 00:00:00 2001
From: schneider <schneider@blinkenlichts.net>
Date: Sat, 23 Jul 2011 23:47:42 +0200
Subject: [PATCH] added random number generator based on adc and xxtea

---
 firmware/applications/default.c |  2 ++
 firmware/basic/Makefile         |  1 +
 firmware/basic/ecc.c            | 18 ++----------------
 firmware/basic/random.c         | 26 ++++++++++++++++++++++++++
 firmware/basic/random.h         |  7 +++++++
 firmware/funk/openbeacon.c      |  2 +-
 firmware/funk/rftransfer.c      |  2 +-
 7 files changed, 40 insertions(+), 18 deletions(-)
 create mode 100644 firmware/basic/random.c
 create mode 100644 firmware/basic/random.h

diff --git a/firmware/applications/default.c b/firmware/applications/default.c
index 2e41ac6..e98a7e2 100644
--- a/firmware/applications/default.c
+++ b/firmware/applications/default.c
@@ -5,6 +5,7 @@
 #include "lcd/fonts/smallfonts.h"
 #include "lcd/print.h"
 #include "filesystem/ff.h"
+#include "basic/random.h"
 
 /**************************************************************************/
 
@@ -92,6 +93,7 @@ int lcdInitConfig(){
 
 void main_default(void) {
     systickInit(10);
+    randomInit();
 
     if(getInputRaw()==BTN_ENTER){
         ISPandReset();
diff --git a/firmware/basic/Makefile b/firmware/basic/Makefile
index 7bbd1bb..c192e24 100644
--- a/firmware/basic/Makefile
+++ b/firmware/basic/Makefile
@@ -15,6 +15,7 @@ OBJS += menu.o
 OBJS += xxtea.o
 OBJS += ecc.o
 OBJS += byteorder.o
+OBJS += random.o
 
 LIBNAME=basic
 
diff --git a/firmware/basic/ecc.c b/firmware/basic/ecc.c
index 321fa8b..7d99523 100644
--- a/firmware/basic/ecc.c
+++ b/firmware/basic/ecc.c
@@ -13,29 +13,15 @@
 #include <stdio.h>
 #include <stdint.h>
 #include "ecc.h"
+#include "random.h"
 
 exp_t base_order;
 elem_t poly;                                      /* the reduction polynomial */
 elem_t coeff_b, base_x, base_y;
 
-static int xrandm=100000000;
-static int xrandm1=10000;
-static int xrandb1=51723621;
-
-int xmult(int p,int q)
-{
-int p1,p0,q1,q0;
-
-p1=p/xrandm1; p0=p%xrandm1;
-q1=q/xrandm1; q0=q%xrandm1;
-return (((p0*q1+p1*q0)%xrandm1)*xrandm1+p0*q0)%xrandm;
-}
-
 unsigned char rnd1()
 {
-static int a=123456789;
-a = (xmult(a,xrandb1)+1)%xrandm;
-return a & 0xff;
+    return random() & 0xFF;
 }
 
 
diff --git a/firmware/basic/random.c b/firmware/basic/random.c
new file mode 100644
index 0000000..26a9c94
--- /dev/null
+++ b/firmware/basic/random.c
@@ -0,0 +1,26 @@
+#include <stdint.h>
+#include "random.h"
+#include "xxtea.h"
+
+#define STATE_SIZE  8
+uint32_t state[STATE_SIZE];
+uint32_t const I[4] = {12,13,14,15};
+
+void randomInit(void)
+{
+    uint32_t i,j,x;
+    for(j=0; j<STATE_SIZE; j++){
+        x = 0;
+        for(i=0; i<10240; i++){
+            x ^= (adcRead(1)&1)<<(i%32);
+        }
+        state[j] = x;
+    }
+    xxtea_encode_words(state, STATE_SIZE, I);
+}
+
+uint32_t random(void)
+{
+    xxtea_encode_words(state, STATE_SIZE, I);
+    return state[0];
+}
diff --git a/firmware/basic/random.h b/firmware/basic/random.h
new file mode 100644
index 0000000..56e5d2b
--- /dev/null
+++ b/firmware/basic/random.h
@@ -0,0 +1,7 @@
+#ifndef _RANDOM_H_
+#define _RANDOM_H_
+
+void randomInit(void);
+uint32_t random(void);
+
+#endif
diff --git a/firmware/funk/openbeacon.c b/firmware/funk/openbeacon.c
index ab90436..599af98 100644
--- a/firmware/funk/openbeacon.c
+++ b/firmware/funk/openbeacon.c
@@ -96,7 +96,7 @@ uint8_t openbeaconSend(void)
     status = openbeaconSendPacket(oid, seq, 0xFF, strength++);
     if( strength == 4 )
         strength = 0;
-    if( seq++ & OPENBEACON_SAVE == OPENBEACON_SAVE )
+    if( (seq++ & OPENBEACON_SAVE) == OPENBEACON_SAVE )
         openbeaconSaveBlock();
     return status;
 }
diff --git a/firmware/funk/rftransfer.c b/firmware/funk/rftransfer.c
index 7c52423..787506f 100644
--- a/firmware/funk/rftransfer.c
+++ b/firmware/funk/rftransfer.c
@@ -12,7 +12,7 @@ void rftransfer_send(uint16_t size, uint8_t *data)
     buf[1] = size >> 8;
     buf[2] = size & 0xFF;
 
-    uint16_t rand = 5; //random_rand16();
+    uint16_t rand = random() & 0xFFFF;
     buf[3] = rand >> 8;
     buf[4] = rand & 0xFF;