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