[PATCH 2/4] perf tools: Introduce cpu_map__snprint_mask()

[Namhyung Kim <namhyung@kernel.org>]

The cpu_map__snprint_mask() is to generate string representation of
cpumask bitmap.  For cpu 0 to 11, it'll return "fff".

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/cpumap.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/cpumap.h |  1 +
 2 files changed, 47 insertions(+)

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 8c7504939113..08540ab2a891 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -673,3 +673,49 @@ size_t cpu_map__snprint(struct cpu_map *map, char *buf, size_t size)
 	pr_debug("cpumask list: %s\n", buf);
 	return ret;
 }
+
+static char hex_char(char val)
+{
+	if (0 <= val && val <= 9)
+		return val + '0';
+	if (10 <= val && val < 16)
+		return val - 10 + 'a';
+	return '?';
+}
+
+size_t cpu_map__snprint_mask(struct cpu_map *map, char *buf, size_t size)
+{
+	int i, cpu;
+	char *ptr = buf;
+	unsigned char *bitmap;
+	int last_cpu = cpu_map__cpu(map, map->nr - 1);
+
+	bitmap = zalloc((last_cpu + 7) / 8);
+	if (bitmap == NULL) {
+		buf[0] = '\0';
+		return 0;
+	}
+
+	for (i = 0; i < map->nr; i++) {
+		cpu = cpu_map__cpu(map, i);
+		bitmap[cpu / 8] |= 1 << (cpu % 8);
+	}
+
+	for (cpu = last_cpu / 4 * 4; cpu >= 0; cpu -= 4) {
+		unsigned char bits = bitmap[cpu / 8];
+
+		if (cpu % 8)
+			bits >>= 4;
+		else
+			bits &= 0xf;
+
+		*ptr++ = hex_char(bits);
+		if ((cpu % 32) == 0 && cpu > 0)
+			*ptr++ = ',';
+	}
+	*ptr = '\0';
+	free(bitmap);
+
+	buf[size - 1] = '\0';
+	return ptr - buf;
+}
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index 1a0549af8f5c..4d231c6eac0c 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -20,6 +20,7 @@ struct cpu_map *cpu_map__dummy_new(void);
 struct cpu_map *cpu_map__new_data(struct cpu_map_data *data);
 struct cpu_map *cpu_map__read(FILE *file);
 size_t cpu_map__snprint(struct cpu_map *map, char *buf, size_t size);
+size_t cpu_map__snprint_mask(struct cpu_map *map, char *buf, size_t size);
 size_t cpu_map__fprintf(struct cpu_map *map, FILE *fp);
 int cpu_map__get_socket_id(int cpu);
 int cpu_map__get_socket(struct cpu_map *map, int idx, void *data);
-- 
2.11.1