ref: fc4bfd57d261e5c99c5d4367adf5c72e8c7e6496
dir: /sys/src/cmd/jpg/jpegdump.c/
/* jpeg parser by tom szymanski */ #include <stddef.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <math.h> #include <ctype.h> /* subroutines done by macros */ #define min(A,B) ((A)<(B) ? (A) : (B)) #define max(A,B) ((A)>(B) ? (A) : (B)) #define maxeql(A,B) if (A < (B)) A = (B); #define mineql(A,B) if (A > (B)) A = (B); #define eatarg0 (argc--, argv++) #define arrayLength(A) ((sizeof A)/ (sizeof A[0])) FILE *infile; char *fname; /* Routines to print error messages of varying severity */ /* externally visible variables */ int warncnt; char *myname; void getname (char *arg) { /* Save name of invoking program for use by error routines */ register char *p; p = strrchr (arg, '/'); if (p == NULL) myname = arg; else myname = ++p; } static void introduction (void) { warncnt++; fflush (stdout); if (myname != NULL) fprintf (stderr, "%s: ", myname); } void warn (char *fmt, ...) { va_list args; introduction (); va_start (args, fmt); vfprintf (stderr, fmt, args); va_end (args); fputc ('\n', stderr); fflush (stderr); } void quit (char *fmt, ...) { va_list args; introduction (); va_start (args, fmt); vfprintf (stderr, fmt, args); va_end (args); fputc ('\n', stderr); fflush (stderr); exit (1); } void fatal (char *fmt, ...) { va_list args; introduction (); va_start (args, fmt); vfprintf (stderr, fmt, args); va_end (args); fprintf (stderr, "\nbetter get help!\n"); fflush (stderr); abort (); } int toption = 0; int dqt[16][64]; int get1 (void) { unsigned char x; if (fread(&x, 1, 1, infile) == 0) quit ("unexpected EOF"); return x; } int get2 (void) { int x; x = get1() << 8; return x | get1(); } void eatmarker (int kind) { int l; l = get2(); printf ("%02x len=%d\n", kind, l); for (l -= 2; l > 0; l--) get1(); } char *sofName[16] = { "Baseline sequential DCT - Huffman coding", "Extended sequential DCT - Huffman coding", "Progressive DCT - Huffman coding", "Lossless - Huffman coding", "4 is otherwise used", "Sequential DCT - differential Huffman coding", "Progressive DCT - differential Huffman coding", "Lossless - differential Huffman coding", "8 is reserved", "Extended Sequential DCT - arithmetic coding", "Progressive DCT - arithmetic coding", "Lossless - arithmetic coding", "c is otherwise used", "Sequential DCT - differential arithmetic coding", "Progressive DCT - differential arithmetic coding", "Lossless - differential arithmetic coding", }; void get_sof (int kind) { int i, length, height, width, precision, ncomponents; int id, sf, tab; length = get2(); precision = get1(); height = get2(); width = get2(); ncomponents = get1(); printf ("SOF%d:\t%s\n", kind - 0xc0, sofName[kind - 0xc0]); printf ("\t%d wide, %d high, %d deep, %d components\n", width, height, precision, ncomponents); for (i = 0; i < ncomponents; i++) { id = get1(); sf = get1(); tab = get1(); printf ("\tcomponent %d: %d hsample, %d vsample, quantization table %d\n", id, sf >> 4, sf & 0xf, tab); } } void get_com (int kind) { int l, c; l = get2(); printf ("COM len=%d '", l); for (l -= 2; l > 0; l--) putchar (c = get1()); printf ("'\n"); } void get_app (int kind) { int l, c, first; char buf[6]; int nbuf, nok; l = get2(); printf ("APP%d len=%d\n", kind - 0xe0, l); nbuf = 0; nok = 0; first = 1; /* dump printable strings in comment */ for (l -= 2; l > 0; l--){ c = get1(); if(isprint(c)){ if(nbuf >= sizeof buf){ if(!first && nbuf == nok) printf(" "); printf("%.*s", nbuf, buf); nbuf = 0; first = 0; } buf[nbuf++] = c; nok++; }else{ if(nok >= sizeof buf) if(nbuf > 0) printf("%.*s", nbuf, buf); nbuf = 0; nok = 0; } } if(nok >= sizeof buf) if(nbuf > 0){ if(!first && nbuf == nok) printf(" "); printf("%.*s", nbuf, buf); } } void get_dac (int kind) { eatmarker (kind); } int get1dqt (void) { int t, p, i, *tab; t = get1(); p = t >> 4; t = t & 0xf; printf ("DQT:\tp = %d, table = %d\n", p, t); tab = &dqt[t][0]; for (i = 0; i < 64; i++) tab[i] = p ? get2() : get1(); if (toption) { for (i = 0; i < 64; i++) printf ("\t%q[%02d] = %d\n", i, tab[i]); } return p ? 65 : 129; } void get_dqt (int kind) { int length; length = get2() - 2; while (length > 0) length -= get1dqt(); } int get1dht (void) { int l, tcth, i, j, v[16], vv[16][256]; tcth = get1(); printf ("DHT:\tclass = %d, table = %d\n", tcth >> 4, tcth & 0xf); for (i = 0; i < 16; i++) v[i] = get1(); l = 17; for (i = 0; i < 16; i++) for (j = 0; j < v[i]; j++) { vv[i][j] = get1(); l += 1; } if (toption) { for (i = 0; i < 16; i++) printf ("\t%l[%02d] = %d\n", i+1, v[i]); for (i = 0; i < 16; i++) for (j = 0; j < v[i]; j++) printf ("\t%v[%02d,%02d] = %d\n", i+1, j+1, vv[i][j]); } return l; } void get_dht (int kind) { int length; length = get2() - 2; while (length > 0) length -= get1dht(); } void get_sos (int kind) { int i, length, ncomponents, id, dcac, ahal; length = get2(); ncomponents = get1(); printf ("SOS:\t%d components\n", ncomponents); for (i = 0; i < ncomponents; i++) { id = get1(); dcac = get1(); printf ("\tcomponent %d: %d DC, %d AC\n", id, dcac >> 4, dcac & 0xf); } printf ("\tstart spectral %d\n", get1()); printf ("\tend spectral %d\n", get1()); ahal = get1(); printf ("\tah = %d, al = %d\n", ahal >> 4, ahal &0xf); } main (int argc, char *argv[]) { int l, stuff, i, j, c; while (argc > 1 && argv[1][0] == '-') { switch (argv[1][1]) { case 't': toption = 1; break; default: warn ("bad option '%c'", argv[1][1]); } eatarg0; } fname = argv[1]; infile = fopen (fname, "r"); if (infile == NULL) quit ("can't open %s\n", fname); Start: // if (get1() != 0xff || get1() != 0xd8) // quit ("not JFIF"); // printf ("SOI\n"); // get_app (0xe0); for (;;) { c = get1(); if (c != 0xff) quit ("expected marker, got %2x", c); do { c = get1(); } while (c == 0xff); marker: switch (c) { case 0xc0: case 0xc1: case 0xc2: case 0xc3: case 0xc5: case 0xc6: case 0xc7: case 0xc8: case 0xc9: case 0xca: case 0xcb: case 0xcd: case 0xce: case 0xcf: get_sof (c); break; case 0xc4: get_dht (c); break; case 0xcc: get_dac (c); break; case 0xd8: printf ("SOI\n"); break; case 0xe0: case 0xe1: case 0xe2: case 0xe3: case 0xe4: case 0xe5: case 0xe6: case 0xe7: case 0xe8: case 0xe9: case 0xea: case 0xeb: case 0xec: case 0xed: case 0xee: case 0xef: get_app(c); break; case 0xda: get_sos (c); goto newentropy; case 0xdb: get_dqt (c); break; case 0xfe: get_com (c); break; case 0xd9: printf ("EOI\n"); if((c=getc(infile)) == EOF) exit(0); ungetc(c, infile); goto Start; default: eatmarker (c); } continue; newentropy: l = stuff = 0; entropy: while ((c = get1()) != 0xff) l += 1; while (c == 0xff) c = get1(); if (c == 0) { stuff += 1; goto entropy; } printf ("sequence length %d with %d stuffs\n", l, stuff); if (0xd0 <= c && c <= 0xd7) { printf ("restart %d\n", c - 0xd0); goto newentropy; } goto marker; } }