From 12e178686331fd0a8e3564a9f0e77fece4a04617 Mon Sep 17 00:00:00 2001
From: Andrey Smirnov <ndreys@bulbasaur.(none)>
Date: Tue, 6 Nov 2012 16:48:40 -0800
Subject: [PATCH] Add a desig_get_unique_id_as_string

This commit adds desig_get_unique_id_as_string which is useful if one
wants to use device ID as USB serial number(iSerialNumber), for example.
---
 include/libopencm3/stm32/f1/desig.h |  9 +++++++++
 lib/stm32/f1/desig.c                | 22 ++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/libopencm3/stm32/f1/desig.h b/include/libopencm3/stm32/f1/desig.h
index 74cfb353..6ceb6658 100644
--- a/include/libopencm3/stm32/f1/desig.h
+++ b/include/libopencm3/stm32/f1/desig.h
@@ -51,6 +51,15 @@ u16 desig_get_flash_size(void);
  */
 void desig_get_unique_id(u32 result[]);
 
+/**
+ * Read the full 96 bit unique identifier and return it as a
+ * zero-terminated string
+ * @param string memory region to write the result to
+ 8 @param string_len the size of string in bytes
+ */
+void desig_get_unique_id_as_string(char *string,
+				   unsigned int string_len);
+
 END_DECLS
 
 #endif
diff --git a/lib/stm32/f1/desig.c b/lib/stm32/f1/desig.c
index 7ae968e1..7f213fab 100644
--- a/lib/stm32/f1/desig.c
+++ b/lib/stm32/f1/desig.c
@@ -35,3 +35,25 @@ void desig_get_unique_id(u32 result[])
     result[1] = bits63_32;
     result[2] = bits31_16 << 16 | bits15_0;
 }
+
+void desig_get_unique_id_as_string(char *string,
+				   unsigned int string_len)
+{
+	int i, len;
+	u8 device_id[12];
+	static const char chars[] = "0123456789ABCDEF";
+
+	desig_get_unique_id((u32 *)device_id);
+
+	/* Each byte produces two characters */
+	len = (2 * sizeof(device_id) < string_len) ?
+		2 * sizeof(device_id) : string_len - 1;
+
+	for (i = 0; i < len; i += 2) {
+		string[i]     = chars[(device_id[i / 2] >> 0) & 0x0F];
+		string[i + 1] = chars[(device_id[i / 2] >> 4) & 0x0F];
+	}
+
+	string[len] = '\0';
+}
+