/*
?*?jpeg.c?-?MJPEG?creator?tool?（https://github.com/nanoant/mjpeg）
?*
?*?Copyright?（c）?2011?Adam?Strzelecki
?*
?*?Permission?is?hereby?granted?free?of?charge?to?any?person?obtaining
?*?a?copy?of?this?software?and?associated?documentation?files?（the
?*?“Software“）?to?deal?in?the?Software?without?restriction?including
?*?without?limitation?the?rights?to?use?copy?modify?merge?publish
?*?distribute?sublicense?and/or?sell?copies?of?the?Software?and?to
?*?permit?persons?to?whom?the?Software?is?furnished?to?do?so?subject?to
?*?the?following?conditions:
?*
?*?The?above?copyright?notice?and?this?permission?notice?shall?be
?*?included?in?all?copies?or?substantial?portions?of?the?Software.
?*
?*?THE?SOFTWARE?IS?PROVIDED?“AS?IS“?WITHOUT?WARRANTY?OF?ANY?KIND
?*?EXPRESS?OR?IMPLIED?INCLUDING?BUT?NOT?LIMITED?TO?THE?WARRANTIES?OF
?*?MERCHANTABILITY?FITNESS?FOR?A?PARTICULAR?PURPOSE?AND
?*?NONINFRINGEMENT.?IN?NO?EVENT?SHALL?THE?AUTHORS?OR?COPYRIGHT?HOLDERS?BE
?*?LIABLE?FOR?ANY?CLAIM?DAMAGES?OR?OTHER?LIABILITY?WHETHER?IN?AN?ACTION
?*?OF?CONTRACT?TORT?OR?OTHERWISE?ARISING?FROM?OUT?OF?OR?IN?CONNECTION
?*?WITH?THE?SOFTWARE?OR?THE?USE?OR?OTHER?DEALINGS?IN?THE?SOFTWARE.
?*/

#include?
#include?
#include?

#define?JPEG_MARKER_MASK?0xFF00
#define?JPEG_HEAD_MARKER?0xFFD8
#define?JPEG_APP0_MARKER?0xFFE0

static?uint16_t?jpeg_markers[]?=?{
	0xFFC0?0xFFC1?0xFFC2?0xFFC3
	0xFFC5?0xFFC6?0xFFC7
	0xFFC9?0xFFCA?0xFFCB
	0xFFCD?0xFFCE?0xFFCF
};

typedef?struct?{
	uint16_t?marker;
	uint16_t?size;
}?__attribute__（（packed））?JPEG_CHUNK;

typedef?struct?{
	uint8_t?unknown;
	uint16_t?height;
	uint16_t?width;
}?__attribute__（（packed））?JPEG_SIZE;

int?jpeg_size（const?char?*path?int?*width?int?*height）
{
	JPEG_CHUNK?chunk;
	JPEG_SIZE?size;
	int?ret?=?0?i;
	FILE?*in?=?fopen（path?“rb“）;
	if（!in）?return?0;

	if（fread（&chunk.marker?1?sizeof（chunk.marker）?in）?==?sizeof（chunk.marker））?{
		chunk.marker?=?ntohs（chunk.marker）;
		if（chunk.marker?==?JPEG_HEAD_MARKER）?{
			while（!ret）?{
				if（fread（&chunk?1?sizeof（chunk）?in）?!=?sizeof（chunk））?break;
				chunk.marker?=?ntohs（chunk.marker）;
				chunk.size???=?ntohs（chunk.size）;
				if（（chunk.marker?&?JPEG_MARKER_MASK）?!=?JPEG_MARKER_MASK）?break;
				for（i?=?0;?i?					if（chunk.marker?==?jpeg_markers[i]）?{
						if（fread（&size?1?sizeof（size）?in）?!=?sizeof（size））?{
							ret?=?0;?break;
						}
						if（width）??*width??=?ntohs（size.width）;
						if（height）?*height?=?ntohs（size.height）;
						ret?=?1;
						break;
					}
				}
				fseek（in?chunk.size?-?sizeof（chunk.size）?SEEK_CUR）;
			}
		}
	}

	fclose（in）;
	return?ret;
}