tools lib: Add bitmap_scnprintf function

Add support to print bitmap list. Code mostly taken from kernel's
bitmap_list_string.

Signed-off-by: Jiri Olsa <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ s/bitmap_snprintf/bitmap_scnprintf/g as it is a scnprintf wrapper, having the same semantics wrt return value ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/include/linux/bitmap.h

···
 	return calloc(1, BITS_TO_LONGS(nbits) * sizeof(unsigned long));
 }
 
+/*
+ * bitmap_scnprintf - print bitmap list into buffer
+ * @bitmap: bitmap
+ * @nbits: size of bitmap
+ * @buf: buffer to store output
+ * @size: size of @buf
+ */
+size_t bitmap_scnprintf(unsigned long *bitmap, int nbits,
+			char *buf, size_t size);
+
 #endif /* _PERF_BITOPS_H */

tools/lib/bitmap.c

···
 	for (k = 0; k < nr; k++)
 		dst[k] = bitmap1[k] | bitmap2[k];
 }
+
+size_t bitmap_scnprintf(unsigned long *bitmap, int nbits,
+			char *buf, size_t size)
+{
+	/* current bit is 'cur', most recently seen range is [rbot, rtop] */
+	int cur, rbot, rtop;
+	bool first = true;
+	size_t ret = 0;
+
+	rbot = cur = find_first_bit(bitmap, nbits);
+	while (cur < nbits) {
+		rtop = cur;
+		cur = find_next_bit(bitmap, nbits, cur + 1);
+		if (cur < nbits && cur <= rtop + 1)
+			continue;
+
+		if (!first)
+			ret += scnprintf(buf + ret, size - ret, ",");
+
+		first = false;
+
+		ret += scnprintf(buf + ret, size - ret, "%d", rbot);
+		if (rbot < rtop)
+			ret += scnprintf(buf + ret, size - ret, "-%d", rtop);
+
+		rbot = cur;
+	}
+	return ret;
+}