1 files changed, 42 insertions, 0 deletions
diff --git a/libar2_encode_base64.c b/libar2_encode_base64.c
new file mode 100644
index 0000000..857b3e8
--- /dev/null
+++ b/libar2_encode_base64.c
@@ -0,0 +1,42 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+#define ALPHABET "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+static char lut[256] = ALPHABET ALPHABET ALPHABET ALPHABET;
+
+#define O1(I1, I2, I3) ((I1) >> 2)
+#define O2(I1, I2, I3) (((I1) << 4) | ((I2) >> 4))
+#define O3(I1, I2, I3) (((I2) << 2) | ((I3) >> 6))
+#define O4(I1, I2, I3) (I3)
+
+
+size_t
+libar2_encode_base64(char *buf, const void *data_, size_t len)
+{
+	const unsigned char *data = data_;
+	size_t q, r, i;
+
+	q = len / 3;
+	r = len % 3;
+
+	if (buf) {
+		for (i = 0; i < q; i++, data += 3) {
+			*buf++ = lut[O1(data[0], data[1], data[2]) & 255];
+	                *buf++ = lut[O2(data[0], data[1], data[2]) & 255];
+			*buf++ = lut[O3(data[0], data[1], data[2]) & 255];
+	                *buf++ = lut[O4(data[0], data[1], data[2]) & 255];
+		}
+		if (r == 1) {
+			*buf++ = lut[O1(data[0], 0, 0) & 255];
+	                *buf++ = lut[O2(data[0], 0, 0) & 255];
+		} else if (r == 2) {
+			*buf++ = lut[O1(data[0], data[1], 0) & 255];
+	                *buf++ = lut[O2(data[0], data[1], 0) & 255];
+			*buf++ = lut[O3(data[0], data[1], 0) & 255];
+		}
+		*buf = '\0';
+	}
+
+	return (q * 4) + r + !!r + 1;
+}