Aegisub/libaegisub/ass/uuencode.cpp

86 lines
2.7 KiB
C++

// Copyright (c) 2013, Thomas Goyne <plorkyeran@aegisub.org>
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
// Aegisub Project http://www.aegisub.org/
#include <libaegisub/ass/uuencode.h>
#include <algorithm>
// Despite being called uuencoding by ass_specs.doc, the format is actually
// somewhat different from real uuencoding. Each 3-byte chunk is split into 4
// 6-bit pieces, then 33 is added to each piece. Lines are wrapped after 80
// characters, and files with non-multiple-of-three lengths are padded with
// zero.
namespace agi { namespace ass {
std::string UUEncode(const char *begin, const char *end, bool insert_linebreaks) {
size_t size = std::distance(begin, end);
std::string ret;
ret.reserve((size * 4 + 2) / 3 + size / 80 * 2);
size_t written = 0;
for (size_t pos = 0; pos < size; pos += 3) {
unsigned char src[3] = { '\0', '\0', '\0' };
memcpy(src, begin + pos, std::min<size_t>(3u, size - pos));
unsigned char dst[4] = {
static_cast<unsigned char>(src[0] >> 2),
static_cast<unsigned char>(((src[0] & 0x3) << 4) | ((src[1] & 0xF0) >> 4)),
static_cast<unsigned char>(((src[1] & 0xF) << 2) | ((src[2] & 0xC0) >> 6)),
static_cast<unsigned char>(src[2] & 0x3F)
};
for (size_t i = 0; i < std::min<size_t>(size - pos + 1, 4u); ++i) {
ret += dst[i] + 33;
if (insert_linebreaks && ++written == 80 && pos + 3 < size) {
written = 0;
ret += "\r\n";
}
}
}
return ret;
}
std::vector<char> UUDecode(const char *begin, const char *end) {
std::vector<char> ret;
size_t len = end - begin;
ret.reserve(len * 3 / 4);
for (size_t pos = 0; pos + 1 < len; ) {
size_t bytes = 0;
unsigned char src[4] = { '\0', '\0', '\0', '\0' };
for (size_t i = 0; i < 4 && pos < len; ++pos) {
char c = begin[pos];
if (c && c != '\n' && c != '\r') {
src[i++] = c - 33;
++bytes;
}
}
if (bytes > 1)
ret.push_back((src[0] << 2) | (src[1] >> 4));
if (bytes > 2)
ret.push_back(((src[1] & 0xF) << 4) | (src[2] >> 2));
if (bytes > 3)
ret.push_back(((src[2] & 0x3) << 6) | (src[3]));
}
return ret;
}
} }