update fpi to support vlongs.

Reference: /n/atom/patch/applied2013/fpivlong
Date: Wed Jul 31 20:52:10 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/port/fpi.c	Wed Jul 31 20:50:42 2013
+++ /sys/src/9/port/fpi.c	Wed Jul 31 20:50:43 2013
@@ -1,6 +1,9 @@
 /*
  * Floating Point Interpreter.
  * shamelessly stolen from an original by ark.
+ *
+ * NB: the Internal arguments to fpisub and fpidiv are reversed from
+ * what you might naively expect: they compute y-x and y/x, respectively.
  */
 #include "../port/fpi.h"
 
--- /sys/src/9/port/fpi.h	Wed Jul 31 20:50:44 2013
+++ /sys/src/9/port/fpi.h	Wed Jul 31 20:50:44 2013
@@ -1,4 +1,5 @@
 typedef long Word;
+typedef long long Vlong;
 typedef unsigned long Single;
 typedef struct {
 	unsigned long l;
@@ -56,6 +57,8 @@
 extern void fpis2i(Internal *, void *);
 extern void fpid2i(Internal *, void *);
 extern void fpiw2i(Internal *, void *);
+extern void fpiv2i(Internal *, void *);
 extern void fpii2s(void *, Internal *);
 extern void fpii2d(void *, Internal *);
 extern void fpii2w(Word *, Internal *);
+extern void fpii2v(Vlong *, Internal *);
--- /sys/src/9/port/fpimem.c	Wed Jul 31 20:50:45 2013
+++ /sys/src/9/port/fpimem.c	Wed Jul 31 20:50:45 2013
@@ -71,6 +71,44 @@
 }
 
 void
+fpiv2i(Internal *i, void *v)
+{
+	Vlong w, word = *(Vlong*)v;
+	short e;
+
+	if(word < 0){
+		i->s = 1;
+		word = -word;
+	}
+	else
+		i->s = 0;
+	if(word == 0){
+		SetZero(i);
+		return;
+	}
+	if(word > 0){
+		for (e = 0, w = word; w; w >>= 1, e++)
+			;
+	} else
+		e = 64;
+	if(e > FractBits){
+		i->h = word>>(e - FractBits);
+		i->l = (word & ((1<<(e - FractBits)) - 1))<<(2*FractBits - e);
+	}
+	else {
+		i->h = word<<(FractBits - e);
+		i->l = 0;
+	}
+	i->e = (e - 1) + ExpBias;
+}
+
+/*
+ * Note that all of these conversions from Internal format
+ * potentially alter *i, so it should be a disposable copy
+ * of the value to be converted.
+ */
+
+void
 fpii2s(void *v, Internal *i)
 {
 	short e;
@@ -128,6 +166,27 @@
 		w = 0x7FFFFFFF;
 	else if(e > FractBits)
 		w = (i->h<<(e - FractBits))|(i->l>>(2*FractBits - e));
+	else
+		w = i->h>>(FractBits-e);
+	if(i->s)
+		w = -w;
+	*word = w;
+}
+
+void
+fpii2v(Vlong *word, Internal *i)
+{
+	Vlong w;
+	short e;
+
+	fpiround(i);
+	e = (i->e - ExpBias) + 1;
+	if(e <= 0)
+		w = 0;
+	else if(e > 63)
+		w = (1ull<<63) - 1;		/* maxlong */
+	else if(e > FractBits)
+		w = (Vlong)i->h<<(e - FractBits) | i->l>>(2*FractBits - e);
 	else
 		w = i->h>>(FractBits-e);
 	if(i->s)