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[unix-history] / usr / src / old / lib2648 / setmat.c

/*      setmat.c        4.1     83/03/09        */
/*
* setmat: set the value in m[r, c] to nval.
*/

#include "bit.h"

setmat(m, rows, cols, r, c, nval)
bitmat m;
int rows, cols, r, c, nval;
{
       register int offset, thisbit;

       if (r<0 || c<0 || r>=rows || c>=cols) {
#ifdef TRACE
               if (trace)
                       fprintf(trace, "setmat range error: (%d, %d) <- %d in a (%d, %d) matrix %x\n", r, c, nval, rows, cols, m);
#endif

               return;
       }
       offset = r*((cols+7)>>3) + (c>>3);
       thisbit = 0x80 >> (c&7);
       if (nval)
               m[offset] |= thisbit;
       else
               m[offset] &= ~thisbit;
}