Create Subversion repository

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 162 insertions, 0 deletions

diff --git a/urt/rle_getskip.c b/urt/rle_getskip.c
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+++ b/urt/rle_getskip.c
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+/*
+ * This software is copyrighted as noted below.  It may be freely copied,
+ * modified, and redistributed, provided that the copyright notice is 
+ * preserved on all copies.
+ * 
+ * There is no warranty or other guarantee of fitness for this software,
+ * it is provided solely "as is".  Bug reports or fixes may be sent
+ * to the author, who may or may not act on them as he desires.
+ *
+ * You may not include this software in a program or other software product
+ * without supplying the source, or without informing the end-user that the 
+ * source is available for no extra charge.
+ *
+ * If you modify this software, you should include a notice giving the
+ * name of the person performing the modification, the date of modification,
+ * and the reason for such modification.
+ */
+/* 
+ * rle_getskip.c - Skip scanlines on input.
+ * 
+ * Author:	Spencer W. Thomas
+ * 		EECS Dept.
+ * 		University of Michigan
+ * Date:	Wed Jun 27 1990
+ * Copyright (c) 1990, University of Michigan
+ */
+
+#include "rle.h"
+#include "rle_code.h"
+
+/* Read a two-byte "short" that started in VAX (LITTLE_ENDIAN) order */
+#define VAXSHORT( var, fp )\
+	{ var = fgetc(fp)&0xFF; var |= (fgetc(fp)) << 8; }
+  
+/* Instruction format -- first byte is opcode, second is datum. */
+
+#define OPCODE(inst) (inst[0] & ~LONG)
+#define LONGP(inst) (inst[0] & LONG)
+#define DATUM(inst) (inst[1] & 0xff)	/* Make sure it's unsigned. */
+
+/*****************************************************************
+ * TAG( rle_getskip )
+ * 
+ * Skip the next scanline with data on it.
+ * Most useful for skipping to end-of-image.
+ * Inputs:
+ * 	the_hdr:	Describes input image.
+ * Outputs:
+ * 	Returns the number of the next scanline.  At EOF returns 32768.
+ * Assumptions:
+ * 	rle_get_setup has been called.
+ * Algorithm:
+ * 	Read input to the beginning of the next scanline, or to EOF or
+ * 	end of image.
+ */
+unsigned int
+rle_getskip( the_hdr )
+rle_hdr *the_hdr;
+{
+    unsigned char inst[2];
+    register FILE *infile = the_hdr->rle_file;
+    int nc;
+
+    /* Add in vertical skip from last scanline */
+    if ( the_hdr->priv.get.vert_skip > 0) 
+	the_hdr->priv.get.scan_y += the_hdr->priv.get.vert_skip;
+    the_hdr->priv.get.vert_skip = 0;
+
+    if ( the_hdr->priv.get.is_eof )
+	return 32768;		/* too big for 16 bits, signal EOF */
+    
+    /* Otherwise, read and interpret instructions until a skipLines
+     * instruction is encountered.
+     */
+    for (;;)
+    {
+        inst[0] = getc( infile );
+	inst[1] = getc( infile );
+	if ( feof(infile) )
+	{
+	    the_hdr->priv.get.is_eof = 1;
+	    break;		/* <--- one of the exits */
+	}
+
+	switch( OPCODE(inst) )
+	{
+	case RSkipLinesOp:
+	    if ( LONGP(inst) )
+	    {
+		VAXSHORT( the_hdr->priv.get.vert_skip, infile );
+	    }
+	    else
+		the_hdr->priv.get.vert_skip = DATUM(inst);
+	    break;			/* need to break for() here, too */
+
+	case RSetColorOp:
+	    /* No-op here. */
+	    break;
+
+	case RSkipPixelsOp:
+	    if ( LONGP(inst) )
+	    {
+		(void)getc( infile );
+		(void)getc( infile );
+	    }
+	    break;
+
+	case RByteDataOp:
+	    if ( LONGP(inst) )
+	    {
+	        VAXSHORT( nc, infile );
+	    }
+	    else
+		nc = DATUM(inst);
+	    nc++;
+	    if ( the_hdr->priv.get.is_seek )
+		fseek( infile, ((nc + 1) / 2) * 2, 1 );
+	    else
+	    {
+		register int ii;
+		for ( ii = ((nc + 1) / 2) * 2; ii > 0; ii-- )
+		    (void) getc( infile );	/* discard it */
+	    }
+
+	    break;
+
+	case RRunDataOp:
+	    if ( LONGP(inst) )
+	    {
+		(void)getc( infile );
+		(void)getc( infile );
+	    }
+	    (void)getc( infile );
+	    (void)getc( infile );
+	    break;
+
+	case REOFOp:
+	    the_hdr->priv.get.is_eof = 1;
+	    break;
+
+	default:
+	    fprintf( stderr,
+		     "%s: rle_getskip: Unrecognized opcode: %d, reading %s\n",
+		     the_hdr->cmd, OPCODE(inst), the_hdr->file_name );
+	    exit(1);
+	}
+	if ( OPCODE(inst) == REOFOp )
+	    break;			/* <--- the other loop exit */
+	if ( OPCODE(inst) == RSkipLinesOp )
+	    break;
+    }
+
+    /* Return the number of the NEXT scanline. */
+    the_hdr->priv.get.scan_y +=
+	the_hdr->priv.get.vert_skip;
+    the_hdr->priv.get.vert_skip = 0;
+
+    if ( the_hdr->priv.get.is_eof )
+	return 32768;		/* too big for 16 bits, signal EOF */
+    else
+	return the_hdr->priv.get.scan_y;
+}