io.parsingdata.metal.format.JPEG Maven / Gradle / Ivy
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A set of Metal format descriptions usable in applications or as examples.
/*
* Copyright 2013-2016 Netherlands Forensic Institute
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.parsingdata.metal.format;
import static io.parsingdata.metal.Shorthand.and;
import static io.parsingdata.metal.Shorthand.cho;
import static io.parsingdata.metal.Shorthand.con;
import static io.parsingdata.metal.Shorthand.def;
import static io.parsingdata.metal.Shorthand.eq;
import static io.parsingdata.metal.Shorthand.gtNum;
import static io.parsingdata.metal.Shorthand.ltNum;
import static io.parsingdata.metal.Shorthand.not;
import static io.parsingdata.metal.Shorthand.or;
import static io.parsingdata.metal.Shorthand.ref;
import static io.parsingdata.metal.Shorthand.rep;
import static io.parsingdata.metal.Shorthand.seq;
import static io.parsingdata.metal.Shorthand.str;
import static io.parsingdata.metal.Shorthand.sub;
import io.parsingdata.metal.token.Token;
/*
* Since nearly every byte of the scan data is individually matched, this
* approach will lead to stack overflow on files of realistic size.
*/
public class JPEG {
private static final Token HEADER =
str("start of image",
seq(def("marker", con(1), eq(con(0xff))),
def("identifier", con(1), eq(con(0xd8)))));
private static final Token FOOTER =
str("end of image",
seq(def("marker", con(1), eq(con(0xff))),
def("identifier", con(1), eq(con(0xd9)))));
private static final Token SIZED_SEGMENT =
str("sized segment",
seq(def("marker", con(1), eq(con(0xff))),
def("identifier", con(1), or(ltNum(con(0xd8)), gtNum(con(0xda)))),
def("length", con(2)),
def("payload", sub(ref("length"), con(2)))));
private static final Token SCAN_SEGMENT =
str("scan segment",
seq(def("marker", con(1), eq(con(0xff))),
def("identifier", con(1), eq(con(0xda))),
def("length", con(2)),
def("payload", sub(ref("length"), con(2))),
rep(cho(def("scandata", con(1), not(eq(con(0xff)))),
def("escape", con(2), or(eq(con(0xff00)), and(gtNum(con(0xffcf)), ltNum(con(0xffd8)))))))));
public static final Token FORMAT =
str("JPEG",
seq(HEADER,
rep(cho(SIZED_SEGMENT, SCAN_SEGMENT)),
FOOTER));
}
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