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Avoid overlong encodings, improve compression ratio

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Peter De Wachter 2018-04-14 13:18:42 +02:00
parent 41c56264a8
commit 4414717ed4
1 changed files with 7 additions and 5 deletions
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12
src/line.cc
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@ -145,10 +145,12 @@ vector<uint8_t> encode_line(const vector<uint8_t> &line,
int num_edits = 0; int num_edits = 0;
auto line_it = line.begin(); auto line_it = line.begin();
auto line_end_it =
std::mismatch(line.rbegin(), line.rend(), reference.rbegin()).first.base();
auto ref_it = reference.begin(); auto ref_it = reference.begin();
while (1) { while (1) {
int offset = skip_to_next_mismatch(&line_it, line.end(), &ref_it); int offset = skip_to_next_mismatch(&line_it, line_end_it, &ref_it);
if (line_it == line.end()) { if (line_it == line_end_it) {
// No more differences, we're done. // No more differences, we're done.
break; break;
} }
@ -156,17 +158,17 @@ vector<uint8_t> encode_line(const vector<uint8_t> &line,
if (++num_edits == max_edits) { if (++num_edits == max_edits) {
// We've run out of edits. Just output the rest of the line in a big // We've run out of edits. Just output the rest of the line in a big
// substitute command. // substitute command.
write_substitute(offset, line_it, line.end(), &output); write_substitute(offset, line_it, line_end_it, &output);
break; break;
} }
int s = substitute_length(line_it, line.end(), ref_it); int s = substitute_length(line_it, line_end_it, ref_it);
if (s > 0) { if (s > 0) {
write_substitute(offset, line_it, std::next(line_it, s), &output); write_substitute(offset, line_it, std::next(line_it, s), &output);
line_it += s; line_it += s;
ref_it += s; ref_it += s;
} else { } else {
int r = repeat_length(line_it, line.end()); int r = repeat_length(line_it, line_end_it);
assert(r >= 2); assert(r >= 2);
write_repeat(offset, r, *line_it, &output); write_repeat(offset, r, *line_it, &output);
line_it += r; line_it += r;