1 files changed, 67 insertions, 0 deletions
diff --git a/src/binhex.c b/src/binhex.c
new file mode 100644
index 0000000..f07aa45
--- /dev/null
+++ b/src/binhex.c
@@ -0,0 +1,67 @@
+// From https://nachtimwald.com/2017/09/24/hex-encode-and-decode-in-c/
+
+#include <stdlib.h>
+#include <string.h>
+#include "binhex.h"
+
+char *bin2hex(const unsigned char *bin, size_t len)
+{
+    char   *out;
+    size_t  i;
+ 
+    if (bin == NULL || len == 0)
+        return NULL;
+ 
+    out = malloc(len*2+1);
+    for (i=0; i<len; i++) {
+        out[i*2]   = "0123456789ABCDEF"[bin[i] >> 4];
+        out[i*2+1] = "0123456789ABCDEF"[bin[i] & 0x0F];
+    }
+    out[len*2] = '\0';
+ 
+    return out;
+}
+
+int hexchr2bin(const char hex, char *out)
+{
+    if (out == NULL)
+        return 0;
+
+    if (hex >= '0' && hex <= '9') {
+        *out = hex - '0';
+    } else if (hex >= 'A' && hex <= 'F') {
+        *out = hex - 'A' + 10;
+    } else if (hex >= 'a' && hex <= 'f') {
+        *out = hex - 'a' + 10;
+    } else {
+        return 0;
+    }
+
+    return 1;
+}
+
+size_t hexs2bin(const char *hex, unsigned char **out)
+{
+    size_t len;
+    char   b1;
+    char   b2;
+    size_t i;
+
+    if (hex == NULL || *hex == '\0' || out == NULL)
+        return 0;
+
+    len = strlen(hex);
+    if (len % 2 != 0)
+        return 0;
+    len /= 2;
+
+    *out = malloc(len);
+    memset(*out, 'A', len);
+    for (i=0; i<len; i++) {
+        if (!hexchr2bin(hex[i*2], &b1) || !hexchr2bin(hex[i*2+1], &b2)) {
+            return 0;
+        }
+        (*out)[i] = (b1 << 4) | b2;
+    }
+    return len;
+}