Subversion Repositories planix.SVN

#include        <u.h>
#include        <libc.h>
#include        <bio.h>

int
Bgetc(Biobufhdr *bp)
{
        int i;

loop:
        i = bp->icount;
        if(i != 0) {
                bp->icount = i+1;
                return bp->ebuf[i];
        }
        if(bp->state != Bractive) {
                if(bp->state == Bracteof)
                        bp->state = Bractive;
                return Beof;
        }
        /*
         * get next buffer, try to keep Bungetsize
         * characters pre-catenated from the previous
         * buffer to allow that many ungets.
         */
        memmove(bp->bbuf-Bungetsize, bp->ebuf-Bungetsize, Bungetsize);
        i = read(bp->fid, bp->bbuf, bp->bsize);
        bp->gbuf = bp->bbuf;
        if(i <= 0) {
                bp->state = Bracteof;
                if(i < 0)
                        bp->state = Binactive;
                return Beof;
        }
        if(i < bp->bsize) {
                memmove(bp->ebuf-i-Bungetsize, bp->bbuf-Bungetsize, i+Bungetsize);
                bp->gbuf = bp->ebuf-i;
        }
        bp->icount = -i;
        bp->offset += i;
        goto loop;
}

int
Bungetc(Biobufhdr *bp)
{

        if(bp->state == Bracteof)
                bp->state = Bractive;
        if(bp->state != Bractive)
                return Beof;
        bp->icount--;
        return 1;
}