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/*
* predictor.c --
*
* Code for predictor calculation. Its macro version, predictor.h,
* is used in non-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.
*/
#include <stdio.h>
#include "MCU.H"
#ifdef 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.
*
*--------------------------------------------------------------
*/
void
Predict(int row,int col,int curComp,MCU *curRowBuf,MCU *prevRowBuf,
int Pr,int Pt,int psv,int *predictor)
/*int row,col; /* position of the pixel to be predicted */
/*int curComp; /* the pixel's component that is predicting */
/*MCU *curRowBuf,*prevRowBuf; /* current and previous row of image */
/*int Pr; /* data precision */
/*int Pt; /* point transformation */
/*int psv; /* predictor selection value */
/*int *predictor; /* preditor value (output) */
{
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.
*
*--------------------------------------------------------------
*/
void
QuickPredict(int col,int curComp,MCU *curRowBuf,MCU *prevRowBuf,int psv,int *predictor)
/*int col; /* column # of the pixel to be predicted */
/*int curComp; /* the pixel's component that is predicting */
/*MCU *curRowBuf,*prevRowBuf; /* current and previous row of image */
/*int psv; /* predictor selection value */
/*int *predictor; /* preditor value (output) */
{
register int left,upper,diag,leftcol;
/*
* All predictor are calculated according to psv.
*/
switch (psv) {
case 0:
*predictor = 0;
break;
case 1:
leftcol = col-1;
left = curRowBuf[leftcol][curComp];
*predictor = left;
break;
case 2:
upper = prevRowBuf[col][curComp];
*predictor = upper;
break;
case 3:
leftcol = col-1;
diag = prevRowBuf[leftcol][curComp];
*predictor = diag;
break;
case 4:
leftcol = col-1;
upper = prevRowBuf[col][curComp];
left = curRowBuf[leftcol][curComp];
diag = prevRowBuf[leftcol][curComp];
*predictor = left + upper - diag;
break;
case 5:
leftcol = col-1;
upper = prevRowBuf[col][curComp];
left = curRowBuf[leftcol][curComp];
diag = prevRowBuf[leftcol][curComp];
*predictor = left+((upper-diag)>>1);
break;
case 6:
leftcol = col-1;
upper = prevRowBuf[col][curComp];
left = curRowBuf[leftcol][curComp];
diag = prevRowBuf[leftcol][curComp];
*predictor = upper+((left-diag)>>1);
break;
case 7:
leftcol = col-1;
upper = prevRowBuf[col][curComp];
left = curRowBuf[leftcol][curComp];
*predictor = (left+upper)>>1;
break;
default:
fprintf(stderr,"Warning: Undefined PSV\n");
*predictor = 0;
}
}
#endif /*DEBUG*/
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