diff options
Diffstat (limited to 'gl/base64.c')
| -rw-r--r-- | gl/base64.c | 40 |
1 files changed, 34 insertions, 6 deletions
diff --git a/gl/base64.c b/gl/base64.c index f9ea4e45c4..568389a903 100644 --- a/gl/base64.c +++ b/gl/base64.c @@ -59,6 +59,27 @@ to_uchar (char ch) return ch; } +static const char b64c[64] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/* Base64 encode IN array of size INLEN into OUT array. OUT needs + to be of length >= BASE64_LENGTH(INLEN), and INLEN needs to be + a multiple of 3. */ +static void +base64_encode_fast (const char *restrict in, size_t inlen, char *restrict out) +{ + while (inlen) + { + *out++ = b64c[to_uchar (in[0]) >> 2]; + *out++ = b64c[((to_uchar (in[0]) << 4) + (to_uchar (in[1]) >> 4)) & 0x3f]; + *out++ = b64c[((to_uchar (in[1]) << 2) + (to_uchar (in[2]) >> 6)) & 0x3f]; + *out++ = b64c[to_uchar (in[2]) & 0x3f]; + + inlen -= 3; + in += 3; + } +} + /* Base64 encode IN array of size INLEN into OUT array of size OUTLEN. If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero @@ -67,28 +88,35 @@ void base64_encode (const char *restrict in, size_t inlen, char *restrict out, size_t outlen) { - static const char b64str[64] = - "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + /* Note this outlen constraint can be enforced at compile time. + I.E. that the output buffer is exactly large enough to hold + the encoded inlen bytes. The inlen constraints (of corresponding + to outlen, and being a multiple of 3) can change at runtime + at the end of input. However the common case when reading + large inputs is to have both constraints satisfied, so we depend + on both in base_encode_fast(). */ + if (outlen % 4 == 0 && inlen == outlen / 4 * 3) + return base64_encode_fast (in, inlen, out); while (inlen && outlen) { - *out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f]; + *out++ = b64c[to_uchar (in[0]) >> 2]; if (!--outlen) break; - *out++ = b64str[((to_uchar (in[0]) << 4) + *out++ = b64c[((to_uchar (in[0]) << 4) + (--inlen ? to_uchar (in[1]) >> 4 : 0)) & 0x3f]; if (!--outlen) break; *out++ = (inlen - ? b64str[((to_uchar (in[1]) << 2) + ? b64c[((to_uchar (in[1]) << 2) + (--inlen ? to_uchar (in[2]) >> 6 : 0)) & 0x3f] : '='); if (!--outlen) break; - *out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '='; + *out++ = inlen ? b64c[to_uchar (in[2]) & 0x3f] : '='; if (!--outlen) break; if (inlen) |