diff options
Diffstat (limited to 'libar2_encode_base64.c')
| -rw-r--r-- | libar2_encode_base64.c | 42 |
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; +} |