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Annotation of 42BSD/usr.lib/lib2648/update.c, revision 1.1

1.1     ! root        1: /*     update.c        4.1     83/03/09        */
        !             2: /*
        !             3:  * update: the key output optimization routine of the whole editor.
        !             4:  * The input consists of two bit matrices (mold is what's on the screen,
        !             5:  * mnew is what we want to be on the screen) and the coordinates of
        !             6:  * the lower left corner on the screen where this matrix is.
        !             7:  * This routine does whatever is necessary to get the screen to look
        !             8:  * like mnew, assuming that it currently looks like mold.
        !             9:  *
        !            10:  * (If I could patent this process for bread and other food I
        !            11:  * would be a rich man.)
        !            12:  */
        !            13: 
        !            14: #include "bit.h"
        !            15: 
        !            16: update(mold, mnew, rows, cols, baser, basec)
        !            17: bitmat mold, mnew;
        !            18: int rows, cols, baser, basec;
        !            19: {
        !            20:        int irow;
        !            21:        register int i, j, k;
        !            22:        int r1, r2, c1, c2, nr1, nr2, nc1, nc2;
        !            23:        extern int QUIET;
        !            24: 
        !            25: #ifdef TRACE
        !            26:        if (trace)
        !            27:                fprintf(trace, "update(mold=%x, mnew=%x, rows=%d, cols=%d, baser=%d, basec=%d)\n", mold, mnew, rows, cols, baser, basec);
        !            28: #endif
        !            29: 
        !            30:        if (QUIET)
        !            31:                return;
        !            32:        aminmax(mold, rows, cols, &r1, &c1, &r2, &c2);
        !            33:        aminmax(mnew, rows, cols, &nr1, &nc1, &nr2, &nc2);
        !            34:        r1 = min(r1, nr1); r2 = max(r2, nr2);
        !            35:        c1 = min(c1, nc1); c2 = max(c2, nc2);
        !            36: 
        !            37:        dumpmat("mold:", mold, rows, cols);
        !            38:        dumpmat("mnew:", mnew, rows, cols);
        !            39: 
        !            40:        for (i=r1; i<=r2; i++) {
        !            41:                irow = baser + rows - i - 1;
        !            42:                if (emptyrow(mnew, rows, cols, i)) {
        !            43:                        if (emptyrow(mold, rows, cols, i)) {
        !            44:                                continue;       /* identically blank. skip. */
        !            45:                        }
        !            46:                        /*
        !            47:                         * Row i is to be cleared.  Look for some more
        !            48:                         * rows to clear and do it all at once.
        !            49:                         */
        !            50:                        for (j=i+1; j<rows && emptyrow(mnew,rows,cols,j); j++)
        !            51:                                ;
        !            52:                        areaclear(baser+rows-j, basec, irow, basec+cols-1);
        !            53:                        i = j-1;        /* skip the others */
        !            54:                } else for (j=c1; j<=c2; j++) {
        !            55:                        /*
        !            56:                         * Result row is not all blank.  We look for stretches
        !            57:                         * of bits that have to be changed (in either
        !            58:                         * direction) and draw an exclusive or line over all
        !            59:                         * the bits in each stretch.
        !            60:                         */
        !            61:                        if (mat(mold,rows,cols,i,j,1)!=mat(mnew,rows,cols,i,j,2)){
        !            62:                                for (k=j+1; k<cols && mat(mold,rows,cols,i,k,3)!=
        !            63:                                        mat(mnew,rows,cols,i,k,4); k++)
        !            64:                                        ;
        !            65:                                k--;
        !            66:                                setxor();
        !            67:                                line(basec+j, irow, basec+k, irow);
        !            68:                                j = k;  /* skip the others */
        !            69:                        }
        !            70:                }
        !            71:        }
        !            72: }

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