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Annotation of researchv10dc/cmd/bison/warshall.c, revision 1.1

1.1     ! root        1: /* Generate transitive closure of a matrix,
        !             2:    Copyright (C) 1984 Bob Corbett and Free Software Foundation, Inc.
        !             3: 
        !             4: BISON is distributed in the hope that it will be useful, but WITHOUT ANY
        !             5: WARRANTY.  No author or distributor accepts responsibility to anyone
        !             6: for the consequences of using it or for whether it serves any
        !             7: particular purpose or works at all, unless he says so in writing.
        !             8: Refer to the BISON General Public License for full details.
        !             9: 
        !            10: Everyone is granted permission to copy, modify and redistribute BISON,
        !            11: but only under the conditions described in the BISON General Public
        !            12: License.  A copy of this license is supposed to have been given to you
        !            13: along with BISON so you can know your rights and responsibilities.  It
        !            14: should be in a file named COPYING.  Among other things, the copyright
        !            15: notice and this notice must be preserved on all copies.
        !            16: 
        !            17:  In other words, you are welcome to use, share and improve this program.
        !            18:  You are forbidden to forbid anyone else to use, share and improve
        !            19:  what you give them.   Help stamp out software-hoarding!  */
        !            20: 
        !            21: #include <stdio.h>
        !            22: #include "machine.h"
        !            23: 
        !            24: 
        !            25: /* given n by n matrix of bits R, modify its contents
        !            26:    to be the transive closure of what was given.  */
        !            27: 
        !            28: TC(R, n)
        !            29: unsigned *R;
        !            30: int n;
        !            31: {
        !            32:   register int rowsize;
        !            33:   register unsigned mask;
        !            34:   register unsigned *rowj;
        !            35:   register unsigned *rp;
        !            36:   register unsigned *rend;
        !            37:   register unsigned *ccol;
        !            38: 
        !            39:   unsigned *relend;
        !            40:   unsigned *cword;
        !            41:   unsigned *rowi;
        !            42: 
        !            43:   rowsize = WORDSIZE(n) * sizeof(unsigned);
        !            44:   relend = (unsigned *) ((char *) R + (n * rowsize));
        !            45: 
        !            46:   cword = R;
        !            47:   mask = 1;
        !            48:   rowi = R;
        !            49:   while (rowi < relend)
        !            50:     {
        !            51:       ccol = cword;
        !            52:       rowj = R;
        !            53: 
        !            54:       while (rowj < relend)
        !            55:        {
        !            56:          if (*ccol & mask)
        !            57:            {
        !            58:              rp = rowi;
        !            59:              rend = (unsigned *) ((char *) rowj + rowsize);
        !            60: 
        !            61:              while (rowj < rend)
        !            62:                *rowj++ |= *rp++;
        !            63:            }
        !            64:          else
        !            65:            {
        !            66:              rowj = (unsigned *) ((char *) rowj + rowsize);
        !            67:            }
        !            68: 
        !            69:          ccol = (unsigned *) ((char *) ccol + rowsize);
        !            70:        }
        !            71: 
        !            72:       mask <<= 1;
        !            73:       if (mask == 0)
        !            74:        {
        !            75:          mask = 1;
        !            76:          cword++;
        !            77:        }
        !            78: 
        !            79:       rowi = (unsigned *) ((char *) rowi + rowsize);
        !            80:     }
        !            81: }
        !            82: 
        !            83: 
        !            84: /* Reflexive Transitive Closure.  Same as TC
        !            85:    and then set all the bits on the diagonal of R.  */
        !            86: 
        !            87: RTC(R, n)
        !            88: unsigned *R;
        !            89: int n;
        !            90: {
        !            91:   register int rowsize;
        !            92:   register unsigned mask;
        !            93:   register unsigned *rp;
        !            94:   register unsigned *relend;
        !            95: 
        !            96:   TC(R, n);
        !            97: 
        !            98:   rowsize = WORDSIZE(n) * sizeof(unsigned);
        !            99:   relend = (unsigned *) ((char *) R + n*rowsize);
        !           100: 
        !           101:   mask = 1;
        !           102:   rp = R;
        !           103:   while (rp < relend)
        !           104:     {
        !           105:       *rp |= mask;
        !           106: 
        !           107:       mask <<= 1;
        !           108:       if (mask == 0)
        !           109:        {
        !           110:          mask = 1;
        !           111:          rp++;
        !           112:        }
        !           113: 
        !           114:       rp = (unsigned *) ((char *) rp + rowsize);
        !           115:     }
        !           116: }

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