perf_counter tools: Add string.[ch]

Add hex conversion libraries. We are going to replace sscanf()
uses with them.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 34 insertions, 0 deletions

diff --git a/Documentation/perf_counter/util/string.c b/Documentation/perf_counter/util/string.c
new file mode 100644
index 000000000000..ec33c0c7f4e2
--- /dev/null
+++ b/Documentation/perf_counter/util/string.c
@@ -0,0 +1,34 @@
+#include "string.h"
+
+static int hex(char ch)
+{
+        if ((ch >= '0') && (ch <= '9'))
+                return ch - '0';
+        if ((ch >= 'a') && (ch <= 'f'))
+                return ch - 'a' + 10;
+        if ((ch >= 'A') && (ch <= 'F'))
+                return ch - 'A' + 10;
+        return -1;
+}
+
+/*
+ * While we find nice hex chars, build a long_val.
+ * Return number of chars processed.
+ */
+int hex2u64(const char *ptr, __u64 *long_val)
+{
+        const char *p = ptr;
+        *long_val = 0;
+
+        while (*p) {
+                const int hex_val = hex(*p);
+
+                if (hex_val < 0)
+                        break;
+
+                *long_val = (*long_val << 4) | hex_val;
+                p++;
+        }
+
+        return p - ptr;
+}