1 files changed, 67 insertions, 0 deletions
diff --git a/src/b64.c b/src/b64.c
new file mode 100644
index 0000000..4c1fe20
--- /dev/null
+++ b/src/b64.c
@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) 2021 Chris Hiszpanski. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author(s) may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "b64.h"
+
+void b64_encode(char *dst, const char *src, size_t size) {
+    const char lut[64] =
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+    char spare = 0;
+    char state = 0;
+
+    while (size || spare) {
+        switch (state) {
+        case 0:
+            *dst++ = lut[((*src) >> 2) & 0x3F];
+            spare = (*src) & 0x3;
+            state = 1;
+            src++;
+            size--;
+            break;
+        case 1:
+            *dst++ = lut[(spare << 4) | (((*src) >> 4) & 0x0F)];
+            spare = (*src) & 0x0F;
+            state = 2;
+            src++;
+            size--;
+            break;
+        case 2:
+            *dst++ = lut[(spare << 2) | (((*src) >> 6) & 0x03)];
+            spare = (*src) & 0x3F;
+            state = 3;
+            size--;
+            break;
+        case 3:
+            *dst++ = lut[spare];
+            spare = 0;
+            state = 0;
+            break;
+        }
+    }
+    *dst = '\0';
+}
+