kernel: lib: Add convert functions for hex strings and binary arrays
Move duplicate hex2bin and add bin2hex function so that application can
use the functions and avoid code duplication.
Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>
diff --git a/lib/os/hex.c b/lib/os/hex.c
new file mode 100644
index 0000000..e9f46f8
--- /dev/null
+++ b/lib/os/hex.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stddef.h>
+#include <zephyr/types.h>
+#include <errno.h>
+#include <sys/util.h>
+
+int char2hex(char c, u8_t *x)
+{
+ if (c >= '0' && c <= '9') {
+ *x = c - '0';
+ } else if (c >= 'a' && c <= 'f') {
+ *x = c - 'a' + 10;
+ } else if (c >= 'A' && c <= 'F') {
+ *x = c - 'A' + 10;
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int hex2char(u8_t x, char *c)
+{
+ if (x <= 9) {
+ *c = x + '0';
+ } else if (x >= 10 && x <= 15) {
+ *c = x - 10 + 'a';
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+size_t bin2hex(const u8_t *buf, size_t buflen, char *hex, size_t hexlen)
+{
+ if ((hexlen + 1) < buflen * 2) {
+ return 0;
+ }
+
+ for (size_t i = 0; i < buflen; i++) {
+ if (hex2char(buf[i] >> 4, &hex[2 * i]) < 0) {
+ return 0;
+ }
+ if (hex2char(buf[i] & 0xf, &hex[2 * i + 1]) < 0) {
+ return 0;
+ }
+ }
+
+ hex[2 * buflen] = '\0';
+ return 2 * buflen;
+}
+
+size_t hex2bin(const char *hex, size_t hexlen, u8_t *buf, size_t buflen)
+{
+ u8_t dec;
+
+ if (buflen < hexlen / 2 + hexlen % 2) {
+ return 0;
+ }
+
+ /* if hexlen is uneven, insert leading zero nibble */
+ if (hexlen % 2) {
+ if (char2hex(hex[0], &dec) < 0) {
+ return 0;
+ }
+ buf[0] = dec;
+ hex++;
+ buf++;
+ }
+
+ /* regular hex conversion */
+ for (size_t i = 0; i < hexlen / 2; i++) {
+ if (char2hex(hex[2 * i], &dec) < 0) {
+ return 0;
+ }
+ buf[i] = dec << 4;
+
+ if (char2hex(hex[2 * i + 1], &dec) < 0) {
+ return 0;
+ }
+ buf[i] += dec;
+ }
+
+ return hexlen / 2 + hexlen % 2;
+}
