1 /* 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 #include <stdarg.h>
9 
10 /* subroutines done by macros */
11 #define min(A,B)	((A)<(B) ? (A) : (B))
12 #define max(A,B)	((A)>(B) ? (A) : (B))
13 #define maxeql(A,B)	if (A < (B)) A = (B);
14 #define mineql(A,B)	if (A > (B)) A = (B);
15 #define eatarg0		(argc--, argv++)
16 #define arrayLength(A) ((sizeof A)/ (sizeof A[0]))
17 
18 FILE *infile;
19 char *fname;
20 
21 /* Routines to print error messages of varying severity */
22 
23 /* externally visible variables */
24 int   warncnt;
25 char *myname;
26 
27 void getname (char *arg) {
28 	/* Save name of invoking program for use by error routines */
29 	register char *p;
30 	p = strrchr (arg, '/');
31 	if (p == NULL)
32 		myname = arg;
33 	else
34 		myname = ++p;
35 }
36 
37 static void introduction (void) {
38 	warncnt++;
39 	fflush (stdout);
40 	if (myname != NULL)
41 		fprintf (stderr, "%s: ", myname);
42 }
43 
44 void warn (char *fmt, ...) {
45 	va_list args;
46 	introduction ();
47 	va_start (args, fmt);
48 	vfprintf (stderr, fmt, args);
49 	va_end (args);
50 	fputc ('\n', stderr);
51 	fflush (stderr);
52 }
53 
54 void quit (char *fmt, ...) {
55 	va_list args;
56 	introduction ();
57 	va_start (args, fmt);
58 	vfprintf (stderr, fmt, args);
59 	va_end (args);
60 	fputc ('\n', stderr);
61 	fflush (stderr);
62 	exit (1);
63 }
64 
65 void fatal (char *fmt, ...) {
66 	va_list args;
67 	introduction ();
68 	va_start (args, fmt);
69 	vfprintf (stderr, fmt, args);
70 	va_end (args);
71 	fprintf (stderr, "\nbetter get help!\n");
72 	fflush (stderr);
73 	abort ();
74 }
75 
76 int toption = 0;
77 int dqt[16][64];
78 
79 int get1 (void) {
80 	unsigned char x;
81 	if (fread(&x, 1, 1, infile) == 0)
82 		quit ("unexpected EOF");
83 	return x;
84 }
85 
86 int get2 (void) {
87 	int x;
88 
89 	x = get1() << 8;
90 	return x | get1();
91 }
92 
93 void eatmarker (int kind) {
94 	int l;
95 	l = get2();
96 	printf ("%02x len=%d\n", kind, l);
97 	for (l -= 2; l > 0; l--)
98 		get1();
99 }
100 
101 char *sofName[16] = {
102 	"Baseline sequential DCT - Huffman coding",
103 	"Extended sequential DCT - Huffman coding",
104 	"Progressive DCT - Huffman coding",
105 	"Lossless - Huffman coding",
106 	"4 is otherwise used",
107 	"Sequential DCT - differential Huffman coding",
108 	"Progressive DCT - differential Huffman coding",
109 	"Lossless - differential Huffman coding",
110 	"8 is reserved",
111 	"Extended Sequential DCT - arithmetic coding",
112 	"Progressive DCT - arithmetic coding",
113 	"Lossless - arithmetic coding",
114 	"c is otherwise used",
115 	"Sequential DCT - differential arithmetic coding",
116 	"Progressive DCT - differential arithmetic coding",
117 	"Lossless - differential arithmetic coding"
118 };
119 
120 void get_sof (int kind) {
121 	int i, length, height, width, precision, ncomponents;
122 	int id, sf, tab;
123 	length = get2();
124 	precision = get1();
125 	height = get2();
126 	width = get2();
127 	ncomponents = get1();
128 	printf ("SOF%d:\t%s\n", kind - 0xc0, sofName[kind - 0xc0]);
129 	printf ("\t%d wide, %d high, %d deep, %d components\n",
130 		width, height, precision, ncomponents);
131 	for (i = 0; i < ncomponents; i++) {
132 		id = get1();
133 		sf = get1();
134 		tab = get1();
135 		printf ("\tcomponent %d: %d hsample, %d vsample, quantization table %d\n",
136 			id, sf >> 4, sf & 0xf, tab);
137 	}
138 }
139 
140 void get_com (int kind) {
141 	int l, c;
142 	l = get2();
143 	printf ("COM len=%d '", l);
144 	for (l -= 2; l > 0; l--)
145 		putchar (c = get1());
146 	printf ("'\n");
147 }
148 
149 void get_app (int kind) {
150 	int l, c, first;
151 	char buf[6];
152 	int nbuf, nok;
153 	l = get2();
154 	printf ("APP%d len=%d\n", kind - 0xe0, l);
155 	nbuf = 0;
156 	nok = 0;
157 	first = 1;
158 	/* dump printable strings in comment */
159 	for (l -= 2; l > 0; l--){
160 		c = get1();
161 		if(isprint(c)){
162 			if(nbuf >= sizeof buf){
163 				if(!first && nbuf == nok)
164 					printf(" ");
165 				printf("%.*s", nbuf, buf);
166 				nbuf = 0;
167 				first = 0;
168 			}
169 			buf[nbuf++] = c;
170 			nok++;
171 		}else{
172 			if(nok >= sizeof buf)
173 				if(nbuf > 0)
174 					printf("%.*s", nbuf, buf);
175 			nbuf = 0;
176 			nok = 0;
177 		}
178 	}
179 	if(nok >= sizeof buf)
180 		if(nbuf > 0){
181 			if(!first && nbuf == nok)
182 				printf(" ");
183 			printf("%.*s", nbuf, buf);
184 		}
185 }
186 
187 void get_dac (int kind) {
188 	eatmarker (kind);
189 }
190 
191 int get1dqt (void) {
192 	int t, p, i, *tab;
193 	t = get1();
194 	p = t >> 4;
195 	t = t & 0xf;
196 	printf ("DQT:\tp = %d, table = %d\n", p, t);
197 	tab = &dqt[t][0];
198 	for (i = 0; i < 64; i++)
199 		tab[i] = p ? get2() : get1();
200 	if (toption) {
201 		for (i = 0; i < 64; i++)
202 			printf ("\t%%q[%02d] = %d\n", i, tab[i]);
203 	}
204 	return p ? 65 : 129;
205 }
206 
207 void get_dqt (int kind) {
208 	int length;
209 	length = get2() - 2;
210 	while (length > 0)
211 		length -= get1dqt();
212 }
213 
214 int get1dht (void) {
215 	int l, tcth, i, j, v[16], vv[16][256];
216 	tcth = get1();
217 	printf ("DHT:\tclass = %d, table = %d\n", tcth >> 4, tcth & 0xf);
218 	for (i = 0; i < 16; i++)
219 		v[i] = get1();
220 	l = 17;
221 	for (i = 0; i < 16; i++)
222 		for (j = 0; j < v[i]; j++) {
223 			vv[i][j] = get1();
224 			l += 1;
225 		}
226 	if (toption) {
227 		for (i = 0; i < 16; i++)
228 			printf ("\t%%l[%02d] = %d\n", i+1, v[i]);
229 		for (i = 0; i < 16; i++)
230 			for (j = 0; j < v[i]; j++)
231 				printf ("\t%%v[%02d,%02d] = %d\n", i+1, j+1, vv[i][j]);
232 	}
233 	return l;
234 }
235 
236 void get_dht (int kind) {
237 	int length;
238 	length = get2() - 2;
239 	while (length > 0)
240 		length -= get1dht();
241 }
242 
243 void get_sos (int kind) {
244 	int i, length, ncomponents, id, dcac, ahal;
245 	length = get2();
246 	ncomponents = get1();
247 	printf ("SOS:\t%d components\n", ncomponents);
248 	for (i = 0; i < ncomponents; i++) {
249 		id = get1();
250 		dcac = get1();
251 		printf ("\tcomponent %d: %d DC, %d AC\n", id, dcac >> 4, dcac & 0xf);
252 	}
253 	printf ("\tstart spectral %d\n", get1());
254 	printf ("\tend spectral %d\n", get1());
255 	ahal = get1();
256 	printf ("\tah = %d, al = %d\n", ahal >> 4, ahal &0xf);
257 }
258 
259 int main (int argc, char *argv[]) {
260 	int l, stuff, c;
261 	while (argc > 1 && argv[1][0] == '-') {
262 		switch (argv[1][1]) {
263 		case 't':
264 			toption = 1;
265 			break;
266 		default:
267 			warn ("bad option '%c'", argv[1][1]);
268 		}
269 		eatarg0;
270 	}
271 	fname = argv[1];
272 	infile = fopen (fname, "r");
273 	if (infile == NULL)
274 		quit ("can't open %s\n", fname);
275     Start:
276 /*	if (get1() != 0xff || get1() != 0xd8) */
277 /*		quit ("not JFIF"); */
278 /*	printf ("SOI\n"); */
279 /*	get_app (0xe0); */
280 	for (;;) {
281 		c = get1();
282 		if (c != 0xff)
283 			quit ("expected marker, got %2x", c);
284 		do {
285 			c = get1();
286 		} while (c == 0xff);
287 marker:
288 		switch (c) {
289 		case 0xc0: case 0xc1: case 0xc2: case 0xc3:
290 		case 0xc5: case 0xc6: case 0xc7:
291 		case 0xc8: case 0xc9: case 0xca: case 0xcb:
292 		case 0xcd: case 0xce: case 0xcf:
293 			get_sof (c);
294 			break;
295 		case 0xc4:
296 			get_dht (c);
297 			break;
298 		case 0xcc:
299 			get_dac (c);
300 			break;
301 		case 0xd8:
302 			printf ("SOI\n");
303 			break;
304 		case 0xe0: case 0xe1: case 0xe2: case 0xe3:
305 		case 0xe4: case 0xe5: case 0xe6: case 0xe7:
306 		case 0xe8: case 0xe9: case 0xea: case 0xeb:
307 		case 0xec: case 0xed: case 0xee: case 0xef:
308 			get_app(c);
309 			break;
310 		case 0xda:
311 			get_sos (c);
312 			goto newentropy;
313 		case 0xdb:
314 			get_dqt (c);
315 			break;
316 		case 0xfe:
317 			get_com (c);
318 			break;
319 		case 0xd9:
320 			printf ("EOI\n");
321 			if((c=getc(infile)) == EOF)
322 				exit(0);
323 			ungetc(c, infile);
324 			goto Start;
325 		default:
326 			eatmarker (c);
327 		}
328 		continue;
329 newentropy:
330 		l = stuff = 0;
331 entropy:
332 		while ((c = get1()) != 0xff)
333 			l += 1;
334 		while (c == 0xff)
335 			c = get1();
336 		if (c == 0) {
337 			stuff += 1;
338 			goto entropy;
339 		}
340 		printf ("sequence length %d with %d stuffs\n", l, stuff);
341 		if (0xd0 <= c && c <= 0xd7) {
342 			printf ("restart %d\n", c - 0xd0);
343 			goto newentropy;
344 		}
345 		goto marker;
346 	}
347 }