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/* jpeg parser by tom szymanski */
2 
#include <stddef.h>
3 
#include <stdlib.h>
4 
#include <stdio.h>
5 
#include <string.h>
6 
#include <math.h>
7 
#include <ctype.h>
8 
 
9 
/* subroutines done by macros */
10 
#define min(A,B)	((A)<(B) ? (A) : (B))
11 
#define max(A,B)	((A)>(B) ? (A) : (B))
12 
#define maxeql(A,B)	if (A < (B)) A = (B);
13 
#define mineql(A,B)	if (A > (B)) A = (B);
14 
#define eatarg0		(argc--, argv++)
15 
#define arrayLength(A) ((sizeof A)/ (sizeof A[0]))
16 
 
17 
FILE *infile;
18 
char *fname;
19 
 
20 
/* Routines to print error messages of varying severity */
21 
 
22 
/* externally visible variables */
23 
int   warncnt;
24 
char *myname;
25 
 
26 
void getname (char *arg) {
27 
	/* Save name of invoking program for use by error routines */
28 
	register char *p;
29 
	p = strrchr (arg, '/');
30 
	if (p == NULL)
31 
		myname = arg;
32 
	else
33 
		myname = ++p;
34 
}
35 
 
36 
static void introduction (void) {
37 
	warncnt++;
38 
	fflush (stdout);
39 
	if (myname != NULL)
40 
		fprintf (stderr, "%s: ", myname);
41 
}
42 
 
43 
void warn (char *fmt, ...) {
44 
	va_list args;
45 
	introduction ();
46 
	va_start (args, fmt);
47 
	vfprintf (stderr, fmt, args);
48 
	va_end (args);
49 
	fputc ('\n', stderr);
50 
	fflush (stderr);
51 
}
52 
 
53 
void quit (char *fmt, ...) {
54 
	va_list args;
55 
	introduction ();
56 
	va_start (args, fmt);
57 
	vfprintf (stderr, fmt, args);
58 
	va_end (args);
59 
	fputc ('\n', stderr);
60 
	fflush (stderr);
61 
	exit (1);
62 
}
63 
 
64 
void fatal (char *fmt, ...) {
65 
	va_list args;
66 
	introduction ();
67 
	va_start (args, fmt);
68 
	vfprintf (stderr, fmt, args);
69 
	va_end (args);
70 
	fprintf (stderr, "\nbetter get help!\n");
71 
	fflush (stderr);
72 
	abort ();
73 
}
74 
 
75 
int toption = 0;
76 
int dqt[16][64];
77 
 
78 
int get1 (void) {
79 
	unsigned char x;
80 
	if (fread(&x, 1, 1, infile) == 0)
81 
		quit ("unexpected EOF");
82 
	return x;
83 
}
84 
 
85 
int get2 (void) {
86 
	int x;
87 
 
88 
	x = get1() << 8;
89 
	return x | get1();
90 
}
91 
 
92 
void eatmarker (int kind) {
93 
	int l, c;
94 
	l = get2();
95 
	printf ("%02x len=%d\n", kind, l);
96 
	for (l -= 2; l > 0; l--)
97 
		get1();
98 
}
99 
 
100 
char *sofName[16] = {
101 
	"Baseline sequential DCT - Huffman coding",
102 
	"Extended sequential DCT - Huffman coding",
103 
	"Progressive DCT - Huffman coding",
104 
	"Lossless - Huffman coding",
105 
	"4 is otherwise used",
106 
	"Sequential DCT - differential Huffman coding",
107 
	"Progressive DCT - differential Huffman coding",
108 
	"Lossless - differential Huffman coding",
109 
	"8 is reserved",
110 
	"Extended Sequential DCT - arithmetic coding",
111 
	"Progressive DCT - arithmetic coding",
112 
	"Lossless - arithmetic coding",
113 
	"c is otherwise used",
114 
	"Sequential DCT - differential arithmetic coding",
115 
	"Progressive DCT - differential arithmetic coding",
116 
	"Lossless - differential arithmetic coding",
117 
};
118 
 
119 
void get_sof (int kind) {
120 
	int i, length, height, width, precision, ncomponents;
121 
	int id, sf, tab;
122 
	length = get2();
123 
	precision = get1();
124 
	height = get2();
125 
	width = get2();
126 
	ncomponents = get1();
127 
	printf ("SOF%d:\t%s\n", kind - 0xc0, sofName[kind - 0xc0]);
128 
	printf ("\t%d wide, %d high, %d deep, %d components\n",
129 
		width, height, precision, ncomponents);
130 
	for (i = 0; i < ncomponents; i++) {
131 
		id = get1();
132 
		sf = get1();
133 
		tab = get1();
134 
		printf ("\tcomponent %d: %d hsample, %d vsample, quantization table %d\n",
135 
			id, sf >> 4, sf & 0xf, tab);
136 
	}
137 
}
138 
 
139 
void get_com (int kind) {
140 
	int l, c;
141 
	l = get2();
142 
	printf ("COM len=%d '", l);
143 
	for (l -= 2; l > 0; l--)
144 
		putchar (c = get1());
145 
	printf ("'\n");
146 
}
147 
 
148 
void get_app (int kind) {
149 
	int l, c, first;
150 
	char buf[6];
151 
	int nbuf, nok;
152 
	l = get2();
153 
	printf ("APP%d len=%d\n", kind - 0xe0, l);
154 
	nbuf = 0;
155 
	nok = 0;
156 
	first = 1;
157 
	/* dump printable strings in comment */
158 
	for (l -= 2; l > 0; l--){
159 
		c = get1();
160 
		if(isprint(c)){
161 
			if(nbuf >= sizeof buf){
162 
				if(!first && nbuf == nok)
163 
					printf(" ");
164 
				printf("%.*s", nbuf, buf);
165 
				nbuf = 0;
166 
				first = 0;
167 
			}
168 
			buf[nbuf++] = c;
169 
			nok++;
170 
		}else{
171 
			if(nok >= sizeof buf)
172 
				if(nbuf > 0)
173 
					printf("%.*s", nbuf, buf);
174 
			nbuf = 0;
175 
			nok = 0;
176 
		}
177 
	}
178 
	if(nok >= sizeof buf)
179 
		if(nbuf > 0){
180 
			if(!first && nbuf == nok)
181 
				printf(" ");
182 
			printf("%.*s", nbuf, buf);
183 
		}
184 
}
185 
 
186 
void get_dac (int kind) {
187 
	eatmarker (kind);
188 
}
189 
 
190 
int get1dqt (void) {
191 
	int t, p, i, *tab;
192 
	t = get1();
193 
	p = t >> 4;
194 
	t = t & 0xf;
195 
	printf ("DQT:\tp = %d, table = %d\n", p, t);
196 
	tab = &dqt[t][0];
197 
	for (i = 0; i < 64; i++)
198 
		tab[i] = p ? get2() : get1();
199 
	if (toption) {
200 
		for (i = 0; i < 64; i++)
201 
			printf ("\t%q[%02d] = %d\n", i, tab[i]);
202 
	}
203 
	return p ? 65 : 129;
204 
}
205 
 
206 
void get_dqt (int kind) {
207 
	int length;
208 
	length = get2() - 2;
209 
	while (length > 0)
210 
		length -= get1dqt();
211 
}
212 
 
213 
int get1dht (void) {
214 
	int l, tcth, p, i, j, v[16], vv[16][256];
215 
	tcth = get1();
216 
	printf ("DHT:\tclass = %d, table = %d\n", tcth >> 4, tcth & 0xf);
217 
	for (i = 0; i < 16; i++)
218 
		v[i] = get1();
219 
	l = 17;
220 
	for (i = 0; i < 16; i++)
221 
		for (j = 0; j < v[i]; j++) {
222 
			vv[i][j] = get1();
223 
			l += 1;
224 
		}
225 
	if (toption) {
226 
		for (i = 0; i < 16; i++)
227 
			printf ("\t%l[%02d] = %d\n", i+1, v[i]);
228 
		for (i = 0; i < 16; i++)
229 
			for (j = 0; j < v[i]; j++)
230 
				printf ("\t%v[%02d,%02d] = %d\n", i+1, j+1, vv[i][j]);
231 
	}
232 
	return l;
233 
}
234 
 
235 
void get_dht (int kind) {
236 
	int length;
237 
	length = get2() - 2;
238 
	while (length > 0)
239 
		length -= get1dht();
240 
}
241 
 
242 
void get_sos (int kind) {
243 
	int i, length, ncomponents, id, dcac, ahal;
244 
	length = get2();
245 
	ncomponents = get1();
246 
	printf ("SOS:\t%d components\n", ncomponents);
247 
	for (i = 0; i < ncomponents; i++) {
248 
		id = get1();
249 
		dcac = get1();
250 
		printf ("\tcomponent %d: %d DC, %d AC\n", id, dcac >> 4, dcac & 0xf);
251 
	}
252 
	printf ("\tstart spectral %d\n", get1());
253 
	printf ("\tend spectral %d\n", get1());
254 
	ahal = get1();
255 
	printf ("\tah = %d, al = %d\n", ahal >> 4, ahal &0xf);
256 
}
257 
 
258 
main (int argc, char *argv[]) {
259 
	int l, stuff, i, j, c;
260 
	while (argc > 1 && argv[1][0] == '-') {
261 
		switch (argv[1][1]) {
262 
		case 't':
263 
			toption = 1;
264 
			break;
265 
		default:
266 
			warn ("bad option '%c'", argv[1][1]);
267 
		}
268 
		eatarg0;
269 
	}
270 
	fname = argv[1];
271 
	infile = fopen (fname, "r");
272 
	if (infile == NULL)
273 
		quit ("can't open %s\n", fname);
274 
    Start:
275 
//	if (get1() != 0xff || get1() != 0xd8)
276 
//		quit ("not JFIF");
277 
//	printf ("SOI\n");
278 
//	get_app (0xe0);
279 
	for (;;) {
280 
		c = get1();
281 
		if (c != 0xff)
282 
			quit ("expected marker, got %2x", c);
283 
		do {
284 
			c = get1();
285 
		} while (c == 0xff);
286 
marker:
287 
		switch (c) {
288 
		case 0xc0: case 0xc1: case 0xc2: case 0xc3:
289 
		case 0xc5: case 0xc6: case 0xc7:
290 
		case 0xc8: case 0xc9: case 0xca: case 0xcb:
291 
		case 0xcd: case 0xce: case 0xcf:
292 
			get_sof (c);
293 
			break;
294 
		case 0xc4:
295 
			get_dht (c);
296 
			break;
297 
		case 0xcc:
298 
			get_dac (c);
299 
			break;
300 
		case 0xd8:
301 
			printf ("SOI\n");
302 
			break;
303 
		case 0xe0: case 0xe1: case 0xe2: case 0xe3:
304 
		case 0xe4: case 0xe5: case 0xe6: case 0xe7:
305 
		case 0xe8: case 0xe9: case 0xea: case 0xeb:
306 
		case 0xec: case 0xed: case 0xee: case 0xef:
307 
			get_app(c);
308 
			break;
309 
		case 0xda:
310 
			get_sos (c);
311 
			goto newentropy;
312 
		case 0xdb:
313 
			get_dqt (c);
314 
			break;
315 
		case 0xfe:
316 
			get_com (c);
317 
			break;
318 
		case 0xd9:
319 
			printf ("EOI\n");
320 
			if((c=getc(infile)) == EOF)
321 
				exit(0);
322 
			ungetc(c, infile);
323 
			goto Start;
324 
		default:
325 
			eatmarker (c);
326 
		}
327 
		continue;
328 
newentropy:
329 
		l = stuff = 0;
330 
entropy:
331 
		while ((c = get1()) != 0xff)
332 
			l += 1;
333 
		while (c == 0xff)
334 
			c = get1();
335 
		if (c == 0) {
336 
			stuff += 1;
337 
			goto entropy;
338 
		}
339 
		printf ("sequence length %d with %d stuffs\n", l, stuff);
340 
		if (0xd0 <= c && c <= 0xd7) {
341 
			printf ("restart %d\n", c - 0xd0);
342 
			goto newentropy;
343 
		}
344 
		goto marker;
345 
	}
346 
}