first usable version of kernel and commands

After an year of hard work, this is a first "usable" version of Jehanne.

qa/kern/float.c

@@ -0,0 +1,61 @@
+#include <u.h>
+#include <libc.h>
+
+#define DPRECSTR	"0.0000004000000000125"
+#define DPREC	0.0000004000000000125
+#define DIEEELO	0x9ac0499f
+#define DIEEEHI	0x3e9ad7f2
+
+jmp_buf errj;
+char *err;
+
+void
+catcher(void *u, char *s)
+{
+	err = 0;
+	if(strncmp(s, "sys: fp:", 8) == 0){
+		err = s;
+		notejmp(u, errj, 0);
+	}
+	noted(NDFLT);
+}
+
+void
+tstdiv(double p)
+{
+	double r = 1.0;
+
+	r /= p;
+	fprint(2, "1/%0.20g = %0.20g\n", p, r);
+} 
+
+void
+main(void)
+{
+	double p = DPREC;
+	int d[2] = { DIEEELO, DIEEEHI };
+	uint64_t dieee, q;
+	dieee = *(uint64_t*)d;
+	q = *(uint64_t*)&p;
+
+	err = 0;
+	notify(catcher);
+	setjmp(errj);
+	if(err){
+		fprint(2, "FAIL: %s\n", err);
+		exits("FAIL");
+	}
+
+	fprint(2, "Double-precision test number: %s\n", DPRECSTR);
+	fprint(2, "Expected internal representation: %ullx\n", dieee);
+	fprint(2, "Actual internal representation: %ullx\n", q);
+
+	if(q != dieee) {
+		print("FAIL\n");
+		exits("FAIL");
+	}
+
+	tstdiv(p);
+	print("PASS\n");
+	exits("PASS");
+}