Initial import

git-svn-id: http://moon:8086/svn/software/trunk/libsrc/libtiff_2007@1 b431acfa-c32f-4a4a-93f1-934dc6c82436
2014-07-19 07:44:42 +00:00
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+/* $Header: /home/cvsroot/libtiff/libtiff/tif_thunder.c,v 1.1.1.1 2000/06/24 19:10:16 tshead Exp $ */
+
+/*
+ * Copyright (c) 1988-1997 Sam Leffler
+ * Copyright (c) 1991-1997 Silicon Graphics, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and 
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that (i) the above copyright notices and this permission notice appear in
+ * all copies of the software and related documentation, and (ii) the names of
+ * Sam Leffler and Silicon Graphics may not be used in any advertising or
+ * publicity relating to the software without the specific, prior written
+ * permission of Sam Leffler and Silicon Graphics.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
+ * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
+ * 
+ * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
+ * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
+ * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+ * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
+ * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
+ * OF THIS SOFTWARE.
+ */
+
+#include "tiffiop.h"
+#ifdef THUNDER_SUPPORT
+/*
+ * TIFF Library.
+ *
+ * ThunderScan 4-bit Compression Algorithm Support
+ */
+
+/*
+ * ThunderScan uses an encoding scheme designed for
+ * 4-bit pixel values.  Data is encoded in bytes, with
+ * each byte split into a 2-bit code word and a 6-bit
+ * data value.  The encoding gives raw data, runs of
+ * pixels, or pixel values encoded as a delta from the
+ * previous pixel value.  For the latter, either 2-bit
+ * or 3-bit delta values are used, with the deltas packed
+ * into a single byte.
+ */
+#define	THUNDER_DATA		0x3f	/* mask for 6-bit data */
+#define	THUNDER_CODE		0xc0	/* mask for 2-bit code word */
+/* code values */
+#define	THUNDER_RUN		0x00	/* run of pixels w/ encoded count */
+#define	THUNDER_2BITDELTAS	0x40	/* 3 pixels w/ encoded 2-bit deltas */
+#define	    DELTA2_SKIP		2	/* skip code for 2-bit deltas */
+#define	THUNDER_3BITDELTAS	0x80	/* 2 pixels w/ encoded 3-bit deltas */
+#define	    DELTA3_SKIP		4	/* skip code for 3-bit deltas */
+#define	THUNDER_RAW		0xc0	/* raw data encoded */
+
+static const int twobitdeltas[4] = { 0, 1, 0, -1 };
+static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
+
+#define	SETPIXEL(op, v) { \
+	lastpixel = (v) & 0xf; \
+	if (npixels++ & 1) \
+	    *op++ |= lastpixel; \
+	else \
+	    op[0] = lastpixel << 4; \
+}
+
+static int
+ThunderDecode(TIFF* tif, tidata_t op, tsize_t maxpixels)
+{
+	register u_char *bp;
+	register tsize_t cc;
+	u_int lastpixel;
+	tsize_t npixels;
+
+	bp = (u_char *)tif->tif_rawcp;
+	cc = tif->tif_rawcc;
+	lastpixel = 0;
+	npixels = 0;
+	while (cc > 0 && npixels < maxpixels) {
+		int n, delta;
+
+		n = *bp++, cc--;
+		switch (n & THUNDER_CODE) {
+		case THUNDER_RUN:		/* pixel run */
+			/*
+			 * Replicate the last pixel n times,
+			 * where n is the lower-order 6 bits.
+			 */
+			if (npixels & 1) {
+				op[0] |= lastpixel;
+				lastpixel = *op++; npixels++; n--;
+			} else
+				lastpixel |= lastpixel << 4;
+			npixels += n;
+			for (; n > 0; n -= 2)
+				*op++ = lastpixel;
+			if (n == -1)
+				*--op &= 0xf0;
+			lastpixel &= 0xf;
+			break;
+		case THUNDER_2BITDELTAS:	/* 2-bit deltas */
+			if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
+				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
+			if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
+				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
+			if ((delta = (n & 3)) != DELTA2_SKIP)
+				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
+			break;
+		case THUNDER_3BITDELTAS:	/* 3-bit deltas */
+			if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
+				SETPIXEL(op, lastpixel + threebitdeltas[delta]);
+			if ((delta = (n & 7)) != DELTA3_SKIP)
+				SETPIXEL(op, lastpixel + threebitdeltas[delta]);
+			break;
+		case THUNDER_RAW:		/* raw data */
+			SETPIXEL(op, n);
+			break;
+		}
+	}
+	tif->tif_rawcp = (tidata_t) bp;
+	tif->tif_rawcc = cc;
+	if (npixels != maxpixels) {
+		TIFFError(tif->tif_name,
+		    "ThunderDecode: %s data at scanline %ld (%lu != %lu)",
+		    npixels < maxpixels ? "Not enough" : "Too much",
+		    (long) tif->tif_row, (long) npixels, (long) maxpixels);
+		return (0);
+	}
+	return (1);
+}
+
+static int
+ThunderDecodeRow(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
+{
+	tidata_t row = buf;
+	
+	(void) s;
+	while ((long)occ > 0) {
+		if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
+			return (0);
+		occ -= tif->tif_scanlinesize;
+		row += tif->tif_scanlinesize;
+	}
+	return (1);
+}
+
+int
+TIFFInitThunderScan(TIFF* tif, int scheme)
+{
+	(void) scheme;
+	tif->tif_decoderow = ThunderDecodeRow;
+	tif->tif_decodestrip = ThunderDecodeRow;
+	return (1);
+}
+#endif /* THUNDER_SUPPORT */