Fix URLs in README, plus two cosmetic fixes to source

One was to make the sum function in magic a little more legible.
The other was to make BINDIR in Makefile overrideable.

Makefile

@@ -1,5 +1,5 @@
 HOSTTYPE = $(shell uname -m)
-BINDIR ?= $(HOME)/bin/$(HOSTTYPE)
+BINDIR = $(HOME)/bin/$(HOSTTYPE)
 CFLAGS = -Wall
 LDLIBS = -L/usr/X11R6/lib -lX11
 

README

@@ -85,12 +85,12 @@ won't lock if the cursor's at the top of the screen.
 Download
 --------
 
-You can [browse the source](http://woozle.org/~neale/repos/?p=xss),
+You can [browse the source](http://woozle.org/~neale/gitweb.cgi?p=xss),
 download a [tarball of the latest
-commit](http://woozle.org/~neale/repos/?p=xss;a=snapshot), or clone the
+commit](http://woozle.org/~neale/gitweb.cgi?p=xss;a=snapshot), or clone
-git repository:
+the git repository:
 
-    git clone http://woozle.org/~neale/repos/xss/
+    git clone http://woozle.org/~neale/projects/xss
 
 
 History

magic.c

@@ -32,20 +32,21 @@
 #define nsec (1000000000 / FPS)
 #define max(a,b) (((a) > (b)) ? (a) : (b))
 
+
+#define randint(x) (random() % (x))
+#define rand(l, h) (randint(h-l) + l)
+
 #define sum(a, b, v, m)     \
   if (b < -v) {             \
     v *= -1;                \
     a = v - b;              \
   } else if (m - b <= v) {  \
     v *= -1;                \
-    a = m - (m - b) + v;    \
+    a = v + b;              \
   } else {                  \
-    a = b + v;              \
+    a = v + b;              \
   }
 
-#define randint(x) (random() % (x))
-#define rand(l, h) (randint(h-l) + l)
-
 int
 main(int argc, char * const argv[])
 {