2.11BSD#431 - /usr/src/new/bm/MoveResidue.c

   1: #include "bm.h"
   2: /* Moves the text which has not been completely searched at the end of
   3: * the buffer to the beginning of the buffer
   4: * and returns number of bytes moved */
   5: 
   6: /*
   7:  * In coordination with the I/O optimization code in Execute, if the Residual
   8:  * is odd in length, we move it to Buffer+1, otherwise to Buffer+0, to make
   9:  * sure that [at least] the next read goes down on an even address.  A pointer
  10:  * to a pointer to the current start of data in the buffer is passed in, that
  11:  * pointer is updated and passed back.
  12:  */
  13: 
  14: int MoveResidue(DescVec, NPats, Buffer, BuffStartP, BuffEnd)
  15: struct PattDesc *DescVec[];
  16: int NPats;
  17: char *Buffer, **BuffStartP, *BuffEnd;
  18: {
  19:     char *FirstStart, *f, *t, *Residue;
  20:     int ResSize, i;
  21:     FirstStart = BuffEnd;
  22:     /* find the earliest point which has not been
  23: 	* completely searched */
  24:     for (i=0; i < NPats; i++) {
  25:         FirstStart =
  26:             min(FirstStart, DescVec[i]-> Start );
  27:     } /* for */
  28:     /* now scan to the beginning of the line containing the
  29: 	* unsearched text */
  30:     for (Residue = FirstStart; *Residue != '\n' &&
  31:     Residue >= *BuffStartP; Residue--);
  32:     if (Residue < *BuffStartP)
  33:         Residue = FirstStart;
  34:     else ++Residue;
  35:     ResSize = (BuffEnd - Residue + 1);
  36:     /* now move the residue to the beginning of
  37: 	* the file */
  38:     t = *BuffStartP = ((unsigned) ResSize & 1) ? Buffer+1 : Buffer;
  39:     f = Residue;
  40:     for(i=ResSize;i;--i)
  41:         *t++ = *f++;
  42:     /* now fix the status vectors */
  43:     for (i=0; i < NPats; i++) {
  44:         DescVec[i]->Start -= (Residue - *BuffStartP);
  45:     } /* for */
  46:     return(ResSize);
  47: } /* MoveResidue */

Defined functions