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Diffstat (limited to 'kernel/kls_ljpeg/ljpeg2ppm/predictor.c')
| -rw-r--r-- | kernel/kls_ljpeg/ljpeg2ppm/predictor.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/kernel/kls_ljpeg/ljpeg2ppm/predictor.c b/kernel/kls_ljpeg/ljpeg2ppm/predictor.c new file mode 100644 index 0000000..36dedfd --- /dev/null +++ b/kernel/kls_ljpeg/ljpeg2ppm/predictor.c @@ -0,0 +1,189 @@ +/* + * 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(row,col,curComp,curRowBuf,prevRowBuf,Pr,Pt,psv,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(col,curComp,curRowBuf,prevRowBuf,psv,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; + + 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*/ |