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/*
* predictor.h --
*
* Code for predictor calculation. Its function version, predictor.c,
* is used in debugging compilation.
*
* Copyright (c) 1994 Kongji Huang and Brian C. Smith.
* Cornell University
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without written agreement is
* hereby granted, provided that the above copyright notice and the following
* two paragraphs appear in all copies of this software.
*
* IN NO EVENT SHALL CORNELL UNIVERSITY BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
* OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF CORNELL
* UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* CORNELL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND CORNELL UNIVERSITY HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#ifndef _PREDICTOR
#define _PREDICTOR
#ifndef DEBUG
/*
*--------------------------------------------------------------
*
* Predict --
*
* Calculate the predictor for pixel[row][col][curComp],
* i.e. curRowBuf[col][curComp]. It handles the all special
* cases at image edges, such as first row and first column
* of a scan.
*
* Results:
* predictor is passed out.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
#define Predict(row,col,curComp,curRowBuf,prevRowBuf,Pr,Pt,psv,predictor)\
{ register int left,upper,diag,leftcol; \
\
leftcol=col-1; \
if (row==0) { \
\
/* \
* The predictor of first pixel is (1<<(Pr-Pt-1), and the \
* predictors for rest of first row are left neighbors. \
*/ \
if (col==0) { \
*predictor = (1<<(Pr-Pt-1)); \
} \
else { \
*predictor = curRowBuf[leftcol][curComp]; \
} \
} \
else { \
\
/* \
* The predictors of first column are upper neighbors. \
* All other preditors are calculated according to psv. \
*/ \
upper=prevRowBuf[col][curComp]; \
if (col==0) \
*predictor = upper; \
else { \
left=curRowBuf[leftcol][curComp]; \
diag=prevRowBuf[leftcol][curComp]; \
switch (psv) { \
case 0: \
*predictor = 0; \
break; \
case 1: \
*predictor = left; \
break; \
case 2: \
*predictor = upper; \
break; \
case 3: \
*predictor = diag; \
break; \
case 4: \
*predictor = left+upper-diag; \
break; \
case 5: \
*predictor = left+((upper-diag)>>1); \
break; \
case 6: \
*predictor = upper+((left-diag)>>1); \
break; \
case 7: \
*predictor = (left+upper)>>1; \
break; \
default: \
fprintf(stderr,"Warning: Undefined PSV\n"); \
*predictor = 0; \
} \
} \
} \
}
/*
*--------------------------------------------------------------
*
* QuickPredict --
*
* Calculate the predictor for sample curRowBuf[col][curComp].
* It does not handle the special cases at image edges, such
* as first row and first column of a scan. We put the special
* case checkings outside so that the computations in main
* loop can be simpler. This has enhenced the performance
* significantly.
*
* Results:
* predictor is passed out.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
#define QuickPredict(col,curComp,curRowBuf,prevRowBuf,psv,predictor){ \
register int left,upper,diag,leftcol; \
\
leftcol=col-1; \
upper=prevRowBuf[col][curComp]; \
left=curRowBuf[leftcol][curComp]; \
diag=prevRowBuf[leftcol][curComp]; \
\
/* \
* All predictor are calculated according to psv. \
*/ \
switch (psv) { \
case 0: \
*predictor = 0; \
break; \
case 1: \
*predictor = left; \
break; \
case 2: \
*predictor = upper; \
break; \
case 3: \
*predictor = diag; \
break; \
case 4: \
*predictor = left+upper-diag; \
break; \
case 5: \
*predictor = left+((upper-diag)>>1); \
break; \
case 6: \
*predictor = upper+((left-diag)>>1); \
break; \
case 7: \
*predictor = (left+upper)>>1; \
break; \
default: \
fprintf(stderr,"Warning: Undefined PSV\n"); \
*predictor = 0; \
} \
}
#endif /* DEBUG */
#endif /* _PREDICTOR */
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