FindFirstBitRun C function

This public domain function called FindFirstBitRun is written in C. It's
documented below. I hope this will help anyone.

/*
 * Finds the next run of bits in a bit buffer and returns its
 * index and size.
 * 
 * @param buffer Points to a buffer of bits. Can't be null; if so, returns 0
 * @param numbits Number of bits in the buffer
 * @param start Points to the first bit to check, when the function returns,
 *  this points to the index of the next bit run. This parameter can't
 *  be null; if so, returns 0

 * @param bitorder Specifies the order of bits in each bytes. If 0, the order

 *  is least-significant bit first; if 1, the order is most significant

 *  bit first.

 * @param findSet If 1, this function will find the next set run of bits,

 *  if 0, this function will find the next clear run of bits

 * @return Number of bits in the next bit run

 */

DWORD FindFirstBitRun(
 LPBYTE buffer,
 DWORD numbits,
 LPDWORD start,
 BOOL bitorder,//if 1, MSB first
 BOOL findSet//if 1, find first set run; if 0, find first clear run

){

 LPBYTE sp,dp;

 int sshift;

 int sstart,send,sinc;

 BYTE v;

 DWORD index,count;

 BYTE beginMask=(findSet)?0:1;

 BYTE endMask=(findSet)?1:0;

 if(!start)return 0;

 if(!buffer || *start>numbits){

  *start=(DWORD)-1;

  return 0;

 }

 index=*start;

 sp=buffer+(index>>3);

 if(bitorder==1){

  sshift=7-(index&7);

  sstart=7;

  send=0;

  sinc=-1;

 } else {

  sshift=(index&7);

  sstart=0;

  send=7;

  sinc=1;

 }

 for(;index>sshift)&0x01);

  if(v^beginMask)break;

  if(sshift==send){sshift=sstart;sp++;}

             else sshift+=sinc;

 }

 if(index>=numbits){

  *start=(DWORD)-1;

  return 0;

 } else {

  *start=index;

 }

 for(count=0;index>sshift)&0x01);

  if(v^endMask)break;

  if(sshift==send){sshift=sstart;sp++;}

             else sshift+=sinc;

 }

 return count;

}