6 files changed, 1101 insertions, 0 deletions

diff --git a/jpg/Makefile b/jpg/Makefile
new file mode 100644
index 0000000..d474c5d
--- /dev/null
+++ b/jpg/Makefile
@@ -0,0 +1,10 @@
+all: z2
+
+z2: z2.c jpg.o
+	gcc -O2 -Wall z2.c jpg.o -o z2
+
+jpg.o: jpg.c
+	gcc -O2 -Wall -c jpg.c
+
+clean:
+	rm -f *~ *.o *.i *.s *.pnm z2
diff --git a/jpg/conv b/jpg/conv
new file mode 100755
index 0000000..31583cb
--- /dev/null
+++ b/jpg/conv
@@ -0,0 +1,35 @@
+#! /usr/bin/perl
+
+# gcc -save-temps -fomit-frame-pointer -Os -Wall -c jpg.c
+# convert: .data -> .text
+# add: .code16gcc
+# convert: .local/.comm foo,bar,??? -> foo: .space bar,0
+# remove: .size, .type, .align
+# remove .section .note...
+# remove .ident
+
+# manually:
+# tmp_img -> %fs
+# fix getbyte, getword -> %es
+
+@f = (<>);
+
+for (@f) {
+  undef $_ if /^\s*\.(size|align|text|section|ident|local|data|file)/;
+  $_ = "\n" if /^\s*\.type/;
+  if(/^\s*\.globl/) {
+    push @globl, "\t$_";
+    undef $_;
+  }
+
+  if(/^\s*\.comm\s+(\S+),(\d+),\d+\s*$/) {
+    push @comm, "\n$1:\n\t.space\t$2,0\n";
+    undef $_;
+  }
+}
+
+print "\t.file\t\"jpeg.S\"\n" . "\t.text\n" . "\t\.code16gcc\n\n";
+print @globl;
+print @comm;
+print @f;
+
diff --git a/jpg/j.jpg b/jpg/j.jpg
new file mode 100644
index 0000000..650bfaf
--- /dev/null
+++ b/jpg/j.jpg
diff --git a/jpg/jpg.c b/jpg/jpg.c
new file mode 100644
index 0000000..58c3f3e
--- /dev/null
+++ b/jpg/jpg.c
@@ -0,0 +1,954 @@
+#include "jpg.h"
+
+#define ERR_NO_SOI 1
+#define ERR_NOT_8BIT 2
+#define ERR_HEIGHT_MISMATCH 3
+#define ERR_WIDTH_MISMATCH 4
+#define ERR_BAD_WIDTH_OR_HEIGHT 5
+#define ERR_TOO_MANY_COMPPS 6
+#define ERR_ILLEGAL_HV 7
+#define ERR_QUANT_TABLE_SELECTOR 8
+#define ERR_NOT_YCBCR_221111 9
+#define ERR_UNKNOWN_CID_IN_SCAN 10
+#define ERR_NOT_SEQUENTIAL_DCT 11
+#define ERR_WRONG_MARKER 12
+#define ERR_NO_EOI 13
+#define ERR_BAD_TABLES 14
+#define ERR_DEPTH_MISMATCH 15
+
+#define ISHIFT 11
+
+#define IFIX(a) ((int)((a) * (1 << ISHIFT) + .5))
+#define IMULT(a, b) (((a) * (b)) >> ISHIFT)
+#define ITOINT(a) ((a) >> ISHIFT)
+
+#ifndef __P
+# define __P(x) x
+#endif
+
+/* special markers */
+#define M_BADHUFF	-1
+#define M_EOF		0x80
+
+struct in {
+	unsigned char *p;
+	unsigned int bits;
+	int left;
+	int marker;
+
+	int (*func) __P((void *));
+	void *data;
+};
+
+/*********************************/
+struct dec_hufftbl;
+struct enc_hufftbl;
+
+union hufftblp {
+	struct dec_hufftbl *dhuff;
+	struct enc_hufftbl *ehuff;
+};
+
+struct scan {
+	int dc;			/* old dc value */
+
+	union hufftblp hudc;
+	union hufftblp huac;
+	int next;		/* when to switch to next scan */
+
+	int cid;		/* component id */
+	int hv;			/* horiz/vert, copied from comp */
+	int tq;			/* quant tbl, copied from comp */
+};
+
+/*********************************/
+
+#define DECBITS 8		/* seems to be the optimum */
+
+struct dec_hufftbl {
+	int maxcode[17];
+	int valptr[16];
+	unsigned char vals[256];
+	unsigned int llvals[1 << DECBITS];
+};
+
+static void decode_mcus __P((struct in *, int *, int, struct scan *, int *));
+static void dec_makehuff __P((struct dec_hufftbl *, int *, unsigned char *));
+
+static void setinput __P((struct in *, unsigned char *));
+/*********************************/
+
+#undef PREC
+#define PREC int
+
+static void idctqtab __P((unsigned char *, PREC *));
+static void idct __P((int *, int *, PREC *, PREC, int));
+static void scaleidctqtab __P((PREC *, PREC));
+
+/*********************************/
+
+static void initcol __P((PREC[][64]));
+
+// static void col221111 __P((int *, unsigned char *, int));
+static void col221111_16 __P((int *, unsigned char *, int));
+
+/*********************************/
+
+#define M_SOI	0xd8
+#define M_APP0	0xe0
+#define M_DQT	0xdb
+#define M_SOF0	0xc0
+#define M_DHT   0xc4
+#define M_DRI	0xdd
+#define M_SOS	0xda
+#define M_RST0	0xd0
+#define M_EOI	0xd9
+#define M_COM	0xfe
+
+static unsigned char *datap;
+static unsigned char tmp_img[16*16*2];
+
+static void memset(void *p, int c, int n)
+{
+  while(n--) *((unsigned char *) p)++ = c;
+}
+
+
+static int getbyte(void)
+{
+	return *datap++;
+}
+
+static int getword(void)
+{
+	int c1, c2;
+	c1 = *datap;
+	c2 = datap[1];
+	datap += 2;
+	return c1 << 8 | c2;
+}
+
+struct comp {
+	int cid;
+	int hv;
+	int tq;
+};
+
+#define MAXCOMP 4
+struct jpginfo {
+	int nc;			/* number of components */
+	int ns;			/* number of scans */
+	int dri;		/* restart interval */
+};
+
+static struct jpginfo info;
+static struct comp comps[MAXCOMP];
+
+static struct scan dscans[MAXCOMP];
+
+static unsigned char quant[4][64];
+
+static struct dec_hufftbl dhuff[4];
+
+#define dec_huffdc (dhuff + 0)
+#define dec_huffac (dhuff + 2)
+
+static struct in in;
+
+static int readtables(int till)
+{
+	int m, l, i, j, lq, pq, tq;
+	int tc, th, tt;
+
+	for (;;) {
+		if (getbyte() != 0xff)
+			return -1;
+		if ((m = getbyte()) == till)
+			break;
+
+		switch (m) {
+		case 0xc2:
+			return 0;
+
+		case M_DQT:
+			lq = getword();
+			while (lq > 2) {
+				pq = getbyte();
+				tq = pq & 15;
+				if (tq > 3)
+					return -1;
+				pq >>= 4;
+				if (pq != 0)
+					return -1;
+				for (i = 0; i < 64; i++)
+					quant[tq][i] = getbyte();
+				lq -= 64 + 1;
+			}
+			break;
+
+		case M_DHT:
+			l = getword();
+			while (l > 2) {
+				int hufflen[16], k;
+				unsigned char huffvals[256];
+
+				tc = getbyte();
+				th = tc & 15;
+				tc >>= 4;
+				tt = tc * 2 + th;
+				if (tc > 1 || th > 1)
+					return -1;
+				for (i = 0; i < 16; i++)
+					hufflen[i] = getbyte();
+				l -= 1 + 16;
+				k = 0;
+				for (i = 0; i < 16; i++) {
+					for (j = 0; j < hufflen[i]; j++)
+						huffvals[k++] = getbyte();
+					l -= hufflen[i];
+				}
+				dec_makehuff(dhuff + tt, hufflen,
+					     huffvals);
+			}
+			break;
+
+		case M_DRI:
+			l = getword();
+			info.dri = getword();
+			break;
+
+		default:
+			l = getword();
+			while (l-- > 2)
+				getbyte();
+			break;
+		}
+	}
+	return 0;
+}
+
+static void dec_initscans(void)
+{
+	int i;
+
+	for (i = 0; i < info.ns; i++)
+		dscans[i].dc = 0;
+}
+
+int jpeg_decode(unsigned char *buf, unsigned char *pic, struct jpeg_decdata *decdata, int x0, int x1, int y0, int y1)
+{
+	int i, j, m, tac, tdc;
+	int mcusx, mcusy, mx, my;
+	int max[6];
+	int width, height;
+	int mx0, mx1, my0, my1;
+
+	if (!decdata)
+		return -1;
+	datap = buf;
+	if (getbyte() != 0xff)
+		return ERR_NO_SOI;
+	if (getbyte() != M_SOI)
+		return ERR_NO_SOI;
+	if (readtables(M_SOF0))
+		return ERR_BAD_TABLES;
+        if(info.dri) return ERR_WRONG_MARKER;
+
+	getword();
+	i = getbyte();
+	if (i != 8)
+		return ERR_NOT_8BIT;
+
+	height = getword();
+	width =  getword();
+
+	info.nc = getbyte();
+	if (info.nc > MAXCOMP)
+		return ERR_TOO_MANY_COMPPS;
+	for (i = 0; i < info.nc; i++) {
+		int h, v;
+		comps[i].cid = getbyte();
+		comps[i].hv = getbyte();
+		v = comps[i].hv & 15;
+		h = comps[i].hv >> 4;
+		comps[i].tq = getbyte();
+		if (h > 3 || v > 3)
+			return ERR_ILLEGAL_HV;
+		if (comps[i].tq > 3)
+			return ERR_QUANT_TABLE_SELECTOR;
+	}
+	if (readtables(M_SOS))
+		return ERR_BAD_TABLES;
+	getword();
+	info.ns = getbyte();
+	if (info.ns != 3)
+		return ERR_NOT_YCBCR_221111;
+	for (i = 0; i < 3; i++) {
+		dscans[i].cid = getbyte();
+		tdc = getbyte();
+		tac = tdc & 15;
+		tdc >>= 4;
+		if (tdc > 1 || tac > 1)
+			return ERR_QUANT_TABLE_SELECTOR;
+		for (j = 0; j < info.nc; j++)
+			if (comps[j].cid == dscans[i].cid)
+				break;
+		if (j == info.nc)
+			return ERR_UNKNOWN_CID_IN_SCAN;
+		dscans[i].hv = comps[j].hv;
+		dscans[i].tq = comps[j].tq;
+		dscans[i].hudc.dhuff = dec_huffdc + tdc;
+		dscans[i].huac.dhuff = dec_huffac + tac;
+	}
+	
+	i = getbyte();
+	j = getbyte();
+	m = getbyte();
+	
+	if (i != 0 || j != 63 || m != 0)
+		return ERR_NOT_SEQUENTIAL_DCT;
+	
+	if (dscans[0].cid != 1 || dscans[1].cid != 2 || dscans[2].cid != 3)
+		return ERR_NOT_YCBCR_221111;
+
+	if (dscans[0].hv != 0x22 || dscans[1].hv != 0x11 || dscans[2].hv != 0x11)
+		return ERR_NOT_YCBCR_221111;
+
+	mcusx = width >> 4;
+	mcusy = height >> 4;
+
+	mx0 = x0 >> 4;
+	my0 = y0 >> 4;
+
+	/* inclusive! */
+	mx1 = ((x1 + 15) >> 4) - 1;
+	my1 = ((y1 + 15) >> 4) - 1;
+
+        if(my1 < mcusy) mcusy = my1 + 1;
+
+	idctqtab(quant[dscans[0].tq], decdata->dquant[0]);
+	idctqtab(quant[dscans[1].tq], decdata->dquant[1]);
+	idctqtab(quant[dscans[2].tq], decdata->dquant[2]);
+	initcol(decdata->dquant);
+	setinput(&in, datap);
+
+	dec_initscans();
+
+	dscans[0].next = 6 - 4;
+	dscans[1].next = 6 - 4 - 1;
+	dscans[2].next = 6 - 4 - 1 - 1;	/* 411 encoding */
+	for (my = 0; my < mcusy; my++) {
+		for (mx = 0; mx < mcusx; mx++) {
+			decode_mcus(&in, decdata->dcts, 6, dscans, max);
+
+			if(
+			  my >= my0 && my <= my1 &&
+			  mx >= mx0 && mx <= mx1
+			) {
+				int i0, i1, j0, j1, yofs;
+
+				idct(decdata->dcts, decdata->out, decdata->dquant[0], IFIX(128.5), max[0]);
+				idct(decdata->dcts + 64, decdata->out + 64, decdata->dquant[0], IFIX(128.5), max[1]);
+				idct(decdata->dcts + 128, decdata->out + 128, decdata->dquant[0], IFIX(128.5), max[2]);
+				idct(decdata->dcts + 192, decdata->out + 192, decdata->dquant[0], IFIX(128.5), max[3]);
+				idct(decdata->dcts + 256, decdata->out + 256, decdata->dquant[1], IFIX(0.5), max[4]);
+				idct(decdata->dcts + 320, decdata->out + 320, decdata->dquant[2], IFIX(0.5), max[5]);
+
+//				if(my == my0 || my == my1 || mx == mx0 || mx == mx1) {
+				  col221111_16(decdata->out, tmp_img, 16 * 2);
+
+				  j0 = my == my0 ? y0 - 16 * my : 0;
+				  j1 = my == my1 ? y1 - 16 * my : 16;
+				  for(j = j0; j < j1; j++) {
+				    yofs = (16 * my - y0 + j) * (x1 - x0);
+				    i0 = mx == mx0 ? x0 - 16 * mx : 0;
+				    i1 = mx == mx1 ? x1 - 16 * mx : 16;
+				    for(i = i0; i < i1; i++) {
+				      *((unsigned short *) pic + 16 * mx - x0 + i + yofs) =
+				      *((unsigned short *) tmp_img + 16 * j + i);
+				    }
+				  }
+//				}
+//				else {
+//				  col221111_16(decdata->out, pic + 2 * ((16 * my - y0) * (x1 - x0) + (16 * mx - x0)), 2 * (x1 - x0));
+//				}
+			}
+		}
+	}
+	
+	return 0;
+}
+
+/****************************************************************/
+/**************       huffman decoder             ***************/
+/****************************************************************/
+
+static int fillbits __P((struct in *, int, unsigned int));
+static int dec_rec2
+__P((struct in *, struct dec_hufftbl *, int *, int, int));
+
+static void setinput(in, p)
+struct in *in;
+unsigned char *p;
+{
+	in->p = p;
+	in->left = 0;
+	in->bits = 0;
+	in->marker = 0;
+}
+
+static int fillbits(in, le, bi)
+struct in *in;
+int le;
+unsigned int bi;
+{
+	int b, m;
+
+	if (in->marker) {
+		if (le <= 16)
+			in->bits = bi << 16, le += 16;
+		return le;
+	}
+	while (le <= 24) {
+		b = *in->p++;
+		if (b == 0xff && (m = *in->p++) != 0) {
+			if (m == M_EOF) {
+				if (in->func && (m = in->func(in->data)) == 0)
+					continue;
+			}
+			in->marker = m;
+			if (le <= 16)
+				bi = bi << 16, le += 16;
+			break;
+		}
+		bi = bi << 8 | b;
+		le += 8;
+	}
+	in->bits = bi;		/* tmp... 2 return values needed */
+	return le;
+}
+
+#define LEBI_DCL	int le, bi
+#define LEBI_GET(in)	(le = in->left, bi = in->bits)
+#define LEBI_PUT(in)	(in->left = le, in->bits = bi)
+
+#define GETBITS(in, n) (					\
+  (le < (n) ? le = fillbits(in, le, bi), bi = in->bits : 0),	\
+  (le -= (n)),							\
+  bi >> le & ((1 << (n)) - 1)					\
+)
+
+#define UNGETBITS(in, n) (	\
+  le += (n)			\
+)
+
+
+static int dec_rec2(in, hu, runp, c, i)
+struct in *in;
+struct dec_hufftbl *hu;
+int *runp;
+int c, i;
+{
+	LEBI_DCL;
+
+	LEBI_GET(in);
+	if (i) {
+		UNGETBITS(in, i & 127);
+		*runp = i >> 8 & 15;
+		i >>= 16;
+	} else {
+		for (i = DECBITS; (c = ((c << 1) | GETBITS(in, 1))) >= (hu->maxcode[i]); i++);
+		if (i >= 16) {
+			in->marker = M_BADHUFF;
+			return 0;
+		}
+		i = hu->vals[hu->valptr[i] + c - hu->maxcode[i - 1] * 2];
+		*runp = i >> 4;
+		i &= 15;
+	}
+	if (i == 0) {		/* sigh, 0xf0 is 11 bit */
+		LEBI_PUT(in);
+		return 0;
+	}
+	/* receive part */
+	c = GETBITS(in, i);
+	if (c < (1 << (i - 1)))
+		c += (-1 << i) + 1;
+	LEBI_PUT(in);
+	return c;
+}
+
+#define DEC_REC(in, hu, r, i)	 (	\
+  r = GETBITS(in, DECBITS),		\
+  i = hu->llvals[r],			\
+  i & 128 ?				\
+    (					\
+      UNGETBITS(in, i & 127),		\
+      r = i >> 8 & 15,			\
+      i >> 16				\
+    )					\
+  :					\
+    (					\
+      LEBI_PUT(in),			\
+      i = dec_rec2(in, hu, &r, r, i),	\
+      LEBI_GET(in),			\
+      i					\
+    )					\
+)
+
+static void decode_mcus(in, dct, n, sc, maxp)
+struct in *in;
+int *dct;
+int n;
+struct scan *sc;
+int *maxp;
+{
+	struct dec_hufftbl *hu;
+	int i, r, t;
+	LEBI_DCL;
+
+	memset(dct, 0, n * 64 * sizeof(*dct));
+	LEBI_GET(in);
+	while (n-- > 0) {
+		hu = sc->hudc.dhuff;
+		*dct++ = (sc->dc += DEC_REC(in, hu, r, t));
+
+		hu = sc->huac.dhuff;
+		i = 63;
+		while (i > 0) {
+			t = DEC_REC(in, hu, r, t);
+			if (t == 0 && r == 0) {
+				dct += i;
+				break;
+			}
+			dct += r;
+			*dct++ = t;
+			i -= r + 1;
+		}
+		*maxp++ = 64 - i;
+		if (n == sc->next)
+			sc++;
+	}
+	LEBI_PUT(in);
+}
+
+static void dec_makehuff(hu, hufflen, huffvals)
+struct dec_hufftbl *hu;
+int *hufflen;
+unsigned char *huffvals;
+{
+	int code, k, i, j, d, x, c, v;
+	for (i = 0; i < (1 << DECBITS); i++)
+		hu->llvals[i] = 0;
+
+/*
+ * llvals layout:
+ *
+ * value v already known, run r, backup u bits:
+ *  vvvvvvvvvvvvvvvv 0000 rrrr 1 uuuuuuu
+ * value unknown, size b bits, run r, backup u bits:
+ *  000000000000bbbb 0000 rrrr 0 uuuuuuu
+ * value and size unknown:
+ *  0000000000000000 0000 0000 0 0000000
+ */
+	code = 0;
+	k = 0;
+	for (i = 0; i < 16; i++, code <<= 1) {	/* sizes */
+		hu->valptr[i] = k;
+		for (j = 0; j < hufflen[i]; j++) {
+			hu->vals[k] = *huffvals++;
+			if (i < DECBITS) {
+				c = code << (DECBITS - 1 - i);
+				v = hu->vals[k] & 0x0f;	/* size */
+				for (d = 1 << (DECBITS - 1 - i); --d >= 0;) {
+					if (v + i < DECBITS) {	/* both fit in table */
+						x = d >> (DECBITS - 1 - v -
+							  i);
+						if (v && x < (1 << (v - 1)))
+							x += (-1 << v) + 1;
+						x = x << 16 | (hu-> vals[k] & 0xf0) << 4 |
+							(DECBITS - (i + 1 + v)) | 128;
+					} else
+						x = v << 16 | (hu-> vals[k] & 0xf0) << 4 |
+						        (DECBITS - (i + 1));
+					hu->llvals[c | d] = x;
+				}
+			}
+			code++;
+			k++;
+		}
+		hu->maxcode[i] = code;
+	}
+	hu->maxcode[16] = 0x20000;	/* always terminate decode */
+}
+
+/****************************************************************/
+/**************             idct                  ***************/
+/****************************************************************/
+
+#define ONE ((PREC)IFIX(1.))
+#define S2  ((PREC)IFIX(0.382683432))
+#define C2  ((PREC)IFIX(0.923879532))
+#define C4  ((PREC)IFIX(0.707106781))
+
+#define S22 ((PREC)IFIX(2 * 0.382683432))
+#define C22 ((PREC)IFIX(2 * 0.923879532))
+#define IC4 ((PREC)IFIX(1 / 0.707106781))
+
+#define C3IC1 ((PREC)IFIX(0.847759065))	/* c3/c1 */
+#define C5IC1 ((PREC)IFIX(0.566454497))	/* c5/c1 */
+#define C7IC1 ((PREC)IFIX(0.198912367))	/* c7/c1 */
+
+#define XPP(a,b) (t = a + b, b = a - b, a = t)
+#define XMP(a,b) (t = a - b, b = a + b, a = t)
+#define XPM(a,b) (t = a + b, b = b - a, a = t)
+
+#define ROT(a,b,s,c) (	t = IMULT(a + b, s),	\
+			a = IMULT(a, c - s) + t,	\
+			b = IMULT(b, c + s) - t)
+
+#define IDCT		\
+(			\
+  XPP(t0, t1),		\
+  XMP(t2, t3),		\
+  t2 = IMULT(t2, IC4) - t3,	\
+  XPP(t0, t3),		\
+  XPP(t1, t2),		\
+  XMP(t4, t7),		\
+  XPP(t5, t6),		\
+  XMP(t5, t7),		\
+  t5 = IMULT(t5, IC4),	\
+  ROT(t4, t6, S22, C22),\
+  t6 -= t7,		\
+  t5 -= t6,		\
+  t4 -= t5,		\
+  XPP(t0, t7),		\
+  XPP(t1, t6),		\
+  XPP(t2, t5),		\
+  XPP(t3, t4)		\
+)
+
+static unsigned char zig2[64] = {
+	0, 2, 3, 9, 10, 20, 21, 35,
+	14, 16, 25, 31, 39, 46, 50, 57,
+	5, 7, 12, 18, 23, 33, 37, 48,
+	27, 29, 41, 44, 52, 55, 59, 62,
+	15, 26, 30, 40, 45, 51, 56, 58,
+	1, 4, 8, 11, 19, 22, 34, 36,
+	28, 42, 43, 53, 54, 60, 61, 63,
+	6, 13, 17, 24, 32, 38, 47, 49
+};
+
+void idct(in, out, quant, off, max)
+int *in;
+int *out;
+PREC *quant;
+PREC off;
+int max;
+{
+	PREC t0, t1, t2, t3, t4, t5, t6, t7, t;
+	PREC tmp[64], *tmpp;
+	int i, j;
+	unsigned char *zig2p;
+
+	t0 = off;
+	if (max == 1) {
+		t0 += in[0] * quant[0];
+		for (i = 0; i < 64; i++)
+			out[i] = ITOINT(t0);
+		return;
+	}
+	zig2p = zig2;
+	tmpp = tmp;
+	for (i = 0; i < 8; i++) {
+		j = *zig2p++;
+		t0 += in[j] * quant[j];
+		j = *zig2p++;
+		t5 = in[j] * quant[j];
+		j = *zig2p++;
+		t2 = in[j] * quant[j];
+		j = *zig2p++;
+		t7 = in[j] * quant[j];
+		j = *zig2p++;
+		t1 = in[j] * quant[j];
+		j = *zig2p++;
+		t4 = in[j] * quant[j];
+		j = *zig2p++;
+		t3 = in[j] * quant[j];
+		j = *zig2p++;
+		t6 = in[j] * quant[j];
+		IDCT;
+		tmpp[0 * 8] = t0;
+		tmpp[1 * 8] = t1;
+		tmpp[2 * 8] = t2;
+		tmpp[3 * 8] = t3;
+		tmpp[4 * 8] = t4;
+		tmpp[5 * 8] = t5;
+		tmpp[6 * 8] = t6;
+		tmpp[7 * 8] = t7;
+		tmpp++;
+		t0 = 0;
+	}
+	for (i = 0; i < 8; i++) {
+		t0 = tmp[8 * i + 0];
+		t1 = tmp[8 * i + 1];
+		t2 = tmp[8 * i + 2];
+		t3 = tmp[8 * i + 3];
+		t4 = tmp[8 * i + 4];
+		t5 = tmp[8 * i + 5];
+		t6 = tmp[8 * i + 6];
+		t7 = tmp[8 * i + 7];
+		IDCT;
+		out[8 * i + 0] = ITOINT(t0);
+		out[8 * i + 1] = ITOINT(t1);
+		out[8 * i + 2] = ITOINT(t2);
+		out[8 * i + 3] = ITOINT(t3);
+		out[8 * i + 4] = ITOINT(t4);
+		out[8 * i + 5] = ITOINT(t5);
+		out[8 * i + 6] = ITOINT(t6);
+		out[8 * i + 7] = ITOINT(t7);
+	}
+}
+
+static unsigned char zig[64] = {
+	0, 1, 5, 6, 14, 15, 27, 28,
+	2, 4, 7, 13, 16, 26, 29, 42,
+	3, 8, 12, 17, 25, 30, 41, 43,
+	9, 11, 18, 24, 31, 40, 44, 53,
+	10, 19, 23, 32, 39, 45, 52, 54,
+	20, 22, 33, 38, 46, 51, 55, 60,
+	21, 34, 37, 47, 50, 56, 59, 61,
+	35, 36, 48, 49, 57, 58, 62, 63
+};
+
+static PREC aaidct[8] = {
+	IFIX(0.3535533906), IFIX(0.4903926402),
+	IFIX(0.4619397663), IFIX(0.4157348062),
+	IFIX(0.3535533906), IFIX(0.2777851165),
+	IFIX(0.1913417162), IFIX(0.0975451610)
+};
+
+
+static void idctqtab(qin, qout)
+unsigned char *qin;
+PREC *qout;
+{
+	int i, j;
+
+	for (i = 0; i < 8; i++)
+		for (j = 0; j < 8; j++)
+			qout[zig[i * 8 + j]] = qin[zig[i * 8 + j]] * 
+			  			IMULT(aaidct[i], aaidct[j]);
+}
+
+static void scaleidctqtab(q, sc)
+PREC *q;
+PREC sc;
+{
+	int i;
+
+	for (i = 0; i < 64; i++)
+		q[i] = IMULT(q[i], sc);
+}
+
+/****************************************************************/
+/**************          color decoder            ***************/
+/****************************************************************/
+
+#define ROUND
+
+/*
+ * YCbCr Color transformation:
+ *
+ * y:0..255   Cb:-128..127   Cr:-128..127
+ *
+ *      R = Y                + 1.40200 * Cr
+ *      G = Y - 0.34414 * Cb - 0.71414 * Cr
+ *      B = Y + 1.77200 * Cb
+ *
+ * =>
+ *      Cr *= 1.40200;
+ *      Cb *= 1.77200;
+ *      Cg = 0.19421 * Cb + .50937 * Cr;
+ *      R = Y + Cr;
+ *      G = Y - Cg;
+ *      B = Y + Cb;
+ *
+ * =>
+ *      Cg = (50 * Cb + 130 * Cr + 128) >> 8;
+ */
+
+static void initcol(q)
+PREC q[][64];
+{
+	scaleidctqtab(q[1], IFIX(1.77200));
+	scaleidctqtab(q[2], IFIX(1.40200));
+}
+
+/* This is optimized for the stupid sun SUNWspro compiler. */
+#define STORECLAMP(a,x)				\
+(						\
+  (a) = (x),					\
+  (unsigned int)(x) >= 256 ? 			\
+    ((a) = (x) < 0 ? 0 : 255)			\
+  :						\
+    0						\
+)
+
+#define CLAMP(x) ((unsigned int)(x) >= 256 ? ((x) < 0 ? 0 : 255) : (x))
+
+#ifdef ROUND
+
+#define CBCRCG(yin, xin)			\
+(						\
+  cb = outc[0 +yin*8+xin],			\
+  cr = outc[64+yin*8+xin],			\
+  cg = (50 * cb + 130 * cr + 128) >> 8		\
+)
+
+#else
+
+#define CBCRCG(yin, xin)			\
+(						\
+  cb = outc[0 +yin*8+xin],			\
+  cr = outc[64+yin*8+xin],			\
+  cg = (3 * cb + 8 * cr) >> 4			\
+)
+
+#endif
+
+#define PIC(yin, xin, p, xout)			\
+(						\
+  y = outy[(yin) * 8 + xin],			\
+  STORECLAMP(p[(xout) * 3 + 0], y + cr),	\
+  STORECLAMP(p[(xout) * 3 + 1], y - cg),	\
+  STORECLAMP(p[(xout) * 3 + 2], y + cb)		\
+)
+
+#ifdef __LITTLE_ENDIAN
+#define PIC_16(yin, xin, p, xout, add)		 \
+(                                                \
+  y = outy[(yin) * 8 + xin],                     \
+  y = ((CLAMP(y + cr + add*2+1) & 0xf8) <<  8) | \
+      ((CLAMP(y - cg + add    ) & 0xfc) <<  3) | \
+      ((CLAMP(y + cb + add*2+1)       ) >>  3),  \
+  p[(xout) * 2 + 0] = y & 0xff,                  \
+  p[(xout) * 2 + 1] = y >> 8                     \
+)
+#else
+#ifdef CONFIG_PPC
+#define PIC_16(yin, xin, p, xout, add)		 \
+(                                                \
+  y = outy[(yin) * 8 + xin],                     \
+  y = ((CLAMP(y + cr + add*2+1) & 0xf8) <<  7) | \
+      ((CLAMP(y - cg + add*2+1) & 0xf8) <<  2) | \
+      ((CLAMP(y + cb + add*2+1)       ) >>  3),  \
+  p[(xout) * 2 + 0] = y >> 8,                    \
+  p[(xout) * 2 + 1] = y & 0xff                   \
+)
+#else
+#define PIC_16(yin, xin, p, xout, add)	 	 \
+(                                                \
+  y = outy[(yin) * 8 + xin],                     \
+  y = ((CLAMP(y + cr + add*2+1) & 0xf8) <<  8) | \
+      ((CLAMP(y - cg + add    ) & 0xfc) <<  3) | \
+      ((CLAMP(y + cb + add*2+1)       ) >>  3),  \
+  p[(xout) * 2 + 0] = y >> 8,                    \
+  p[(xout) * 2 + 1] = y & 0xff                   \
+)
+#endif
+#endif
+
+#define PIC221111(xin)						\
+(								\
+  CBCRCG(0, xin),						\
+  PIC(xin / 4 * 8 + 0, (xin & 3) * 2 + 0, pic0, xin * 2 + 0),	\
+  PIC(xin / 4 * 8 + 0, (xin & 3) * 2 + 1, pic0, xin * 2 + 1),	\
+  PIC(xin / 4 * 8 + 1, (xin & 3) * 2 + 0, pic1, xin * 2 + 0),	\
+  PIC(xin / 4 * 8 + 1, (xin & 3) * 2 + 1, pic1, xin * 2 + 1)	\
+)
+
+#define PIC221111_16(xin)                                               \
+(                                                               	\
+  CBCRCG(0, xin),                                               	\
+  PIC_16(xin / 4 * 8 + 0, (xin & 3) * 2 + 0, pic0, xin * 2 + 0, 3),     \
+  PIC_16(xin / 4 * 8 + 0, (xin & 3) * 2 + 1, pic0, xin * 2 + 1, 0),     \
+  PIC_16(xin / 4 * 8 + 1, (xin & 3) * 2 + 0, pic1, xin * 2 + 0, 1),     \
+  PIC_16(xin / 4 * 8 + 1, (xin & 3) * 2 + 1, pic1, xin * 2 + 1, 2)      \
+)
+
+#if 0
+static void col221111(out, pic, width)
+int *out;
+unsigned char *pic;
+int width;
+{
+	int i, j, k;
+	unsigned char *pic0, *pic1;
+	int *outy, *outc;
+	int cr, cg, cb, y;
+
+	pic0 = pic;
+	pic1 = pic + width;
+	outy = out;
+	outc = out + 64 * 4;
+	for (i = 2; i > 0; i--) {
+		for (j = 4; j > 0; j--) {
+			for (k = 0; k < 8; k++) {
+				PIC221111(k);
+			}
+			outc += 8;
+			outy += 16;
+			pic0 += 2 * width;
+			pic1 += 2 * width;
+		}
+		outy += 64 * 2 - 16 * 4;
+	}
+}
+#endif
+
+void col221111_16(out, pic, width)
+int *out;
+unsigned char *pic;
+int width;
+{
+	int i, j, k;
+	unsigned char *pic0, *pic1;
+	int *outy, *outc;
+	int cr, cg, cb, y;
+
+	pic0 = pic;
+	pic1 = pic + width;
+	outy = out;
+	outc = out + 64 * 4;
+	for (i = 2; i > 0; i--) {
+		for (j = 4; j > 0; j--) {
+			for (k = 0; k < 8; k++) {
+			    PIC221111_16(k);
+			}
+			outc += 8;
+			outy += 16;
+			pic0 += 2 * width;
+			pic1 += 2 * width;
+		}
+		outy += 64 * 2 - 16 * 4;
+	}
+}
+
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+void jpeg_get_size(unsigned char *buf, int *width, int *height)
+{
+  int i;
+
+  datap = buf;
+  getbyte(); getbyte(); 
+  readtables(M_SOF0);
+  getword(); getbyte();
+
+  i = getword();
+  if(height) *height = i;
+  i = getword();
+  if(width) *width = i;
+}
+
diff --git a/jpg/jpg.h b/jpg/jpg.h
new file mode 100644
index 0000000..7031811
--- /dev/null
+++ b/jpg/jpg.h
@@ -0,0 +1,8 @@
+struct jpeg_decdata {
+  int dcts[6 * 64 + 16];
+  int out[64 * 6];
+  int dquant[3][64];
+};
+
+int jpeg_decode(unsigned char *jpg, unsigned char *img, struct jpeg_decdata *jdd, int x_0, int x_1, int y_0, int y_1);
+void jpeg_get_size(unsigned char *buf, int *width, int *height);
diff --git a/jpg/z2.c b/jpg/z2.c
new file mode 100644
index 0000000..1f29d7f
--- /dev/null
+++ b/jpg/z2.c
@@ -0,0 +1,94 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "jpg.h"
+
+int main(int argc, char **argv)
+{
+  int fd, i, width, height;
+  unsigned char *jpg = malloc(1 << 20);
+  unsigned char *img, *p;
+  struct jpeg_decdata jdd;
+  unsigned bits = 16;
+  unsigned char pixel[3];
+  unsigned x;
+  unsigned x0, x1, y0, y1;
+
+  if(argc < 2) return 1;
+
+  fd = open(argv[1], O_RDONLY);
+
+  if(fd == -1) return 2;
+
+  i = read(fd, jpg, 1 << 20);
+
+  if(i < 0) return 3;
+
+  close(fd);
+
+  jpg = realloc(jpg, i);
+
+  jpeg_get_size(jpg, &width, &height);
+
+  fprintf(stderr, "size = %d bytes, width = %d, height = %d\n", i, width, height);
+
+  img = malloc(width * height * 4);
+
+  x0 = 10;
+  x1 = 170;
+  y0 = 20;
+  y1 = 177;
+
+  i = jpeg_decode(jpg, img, &jdd, x0, x1, y0, y1);
+
+  width = x1 - x0;
+  height = y1 - y0;
+
+  fprintf(stderr, "decode = %d\n", i);
+
+  if(argc >= 3) {
+
+    fd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+    if(fd >= 0) {
+      char *s = NULL;
+
+      i = asprintf(&s, "P6\n%d %d\n255\n", width, height);
+      if(i > 0) write(fd, s, i);
+
+      free(s);
+
+      for(i = 0, p = img; i < width * height; i++) {
+        if(bits == 24) {
+          pixel[0] = *p++;
+          pixel[1] = *p++;
+          pixel[2] = *p++;
+        }
+        else {
+          x = p[1] + (p[0] << 8);
+          p += 2;
+
+          pixel[0] = ((x >> 11) & 0x1f) << 3;
+          pixel[0] += pixel[0] >> 5;
+          pixel[1] = ((x >> 5) & 0x3f) << 2;
+          pixel[1] += pixel[1] >> 6;
+          pixel[2] = (x & 0x1f) << 3;
+          pixel[2] += pixel[2] >> 5;
+        }
+
+        write(fd, &pixel, 3);
+      }
+
+      close(fd);
+    }
+  }
+
+  return 0;
+}
+
+