replace call to rand() with android_only function that reads two bytes

from /dev/urandom.  rand() has been returning pretty crappy numbers
resulting in lots of clustering of tiles in trays.  Let's see if this
is any better.

xwords4/android/XWords4/jni/Android.mk

@@ -10,7 +10,7 @@ local_C_INCLUDES+= \
 
 local_LDLIBS += -llog
 
-# local_DEBUG = -DMEM_DEBUG -DDEBUG -DENABLE_LOGGING
+local_DEBUG = -DMEM_DEBUG -DDEBUG -DENABLE_LOGGING
 local_DEFINES += \
 	$(local_DEBUG) \
 	-DXWFEATURE_RELAY \
@@ -18,6 +18,7 @@ local_DEFINES += \
 	-DXWFEATURE_CHAT \
 	-DSHOW_PROGRESS \
 	-DKEY_SUPPORT \
+	-DPLATFORM_ANDROID \
 	-DXWFEATURE_CROSSHAIRS \
 	-DPOINTER_SUPPORT \
 	-DSCROLL_DRAG_THRESHHOLD=1 \

xwords4/android/XWords4/jni/andutils.c

@@ -18,6 +18,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
 #include "andutils.h"
 
 #include "comtypes.h"
@@ -452,6 +456,17 @@ and_empty_stream( MPFORMAL AndGlobals* globals )
     return stream;
 }
 
+XP_U16
+and_rand( void )
+{
+    XP_U16 num;
+    int fd = open( "/dev/urandom", O_RDONLY );
+    XP_ASSERT( fd >= 0 );
+    (void)read( fd, &num, sizeof(num) );
+    close( fd );
+    return num;
+}
+
 /* #ifdef DEBUG */
 /* XP_U32 */
 /* andy_rand( const char* caller ) */

xwords4/android/XWords4/jni/xptypes.h

@@ -48,7 +48,7 @@ typedef XP_U32 XP_Time;
 #define XP_CR "\n"
 #define XP_LD "%ld"
 
-# define XP_RANDOM() rand()
+#define XP_RANDOM() and_rand()
 
 #ifdef MEM_DEBUG
 # define XP_PLATMALLOC(nbytes) malloc(nbytes)
@@ -95,6 +95,8 @@ void and_assert( const char* test, int line, const char* file, const char* func
 #define XP_WARNF(...)
 #endif
 
+XP_U16 and_rand(void);
+
 XP_U32 and_ntohl(XP_U32 l);
 XP_U16 and_ntohs(XP_U16 s);
 XP_U32 and_htonl(XP_U32 l);
@@ -114,4 +116,3 @@ extern "C" {
 #endif
 
 #endif
-

xwords4/common/pool.c

@@ -132,10 +132,12 @@ getRandomTile( PoolContext* pool )
     
 #if defined PLATFORM_PALM && ! defined XW_TARGET_PNO
     XP_U16 rr = XP_RANDOM();
+#elif defined PLATFORM_ANDROID
+    XP_U16 rr = XP_RANDOM();
 #else
     XP_U16 rr = (XP_U16)(XP_RANDOM()>>16);
 #endif
-    XP_U16 index = (XP_U16)(rr % pool->numTilesLeft);
+    XP_U16 index = rr % pool->numTilesLeft;
     Tile result = getNthPoolTile( pool, index );
 
     --pool->lettersLeft[result];