Subversion Repositories planix.SVN

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

/* score of a zero length block */
uchar   vtZeroScore[VtScoreSize] = {
        0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d, 0x32, 0x55,
        0xbf, 0xef, 0x95, 0x60, 0x18, 0x90, 0xaf, 0xd8, 0x07, 0x09
};


int
vtZeroExtend(int type, uchar *buf, int n, int nn)
{
        uchar *p, *ep;

        switch(type) {
        default:
                memset(buf+n, 0, nn-n);
                break;
        case VtPointerType0:
        case VtPointerType1:
        case VtPointerType2:
        case VtPointerType3:
        case VtPointerType4:
        case VtPointerType5:
        case VtPointerType6:
        case VtPointerType7:
        case VtPointerType8:
        case VtPointerType9:
                p = buf + (n/VtScoreSize)*VtScoreSize;
                ep = buf + (nn/VtScoreSize)*VtScoreSize;
                while(p < ep) {
                        memmove(p, vtZeroScore, VtScoreSize);
                        p += VtScoreSize;
                }
                memset(p, 0, buf+nn-p);
                break;
        }
        return 1;
}

int 
vtZeroTruncate(int type, uchar *buf, int n)
{
        uchar *p;

        switch(type) {
        default:
                for(p = buf + n; p > buf; p--) {
                        if(p[-1] != 0)
                                break;
                }
                return p - buf;
        case VtRootType:
                if(n < VtRootSize)
                        return n;
                return VtRootSize;
        case VtPointerType0:
        case VtPointerType1:
        case VtPointerType2:
        case VtPointerType3:
        case VtPointerType4:
        case VtPointerType5:
        case VtPointerType6:
        case VtPointerType7:
        case VtPointerType8:
        case VtPointerType9:
                /* ignore slop at end of block */
                p = buf + (n/VtScoreSize)*VtScoreSize;

                while(p > buf) {
                        if(memcmp(p - VtScoreSize, vtZeroScore, VtScoreSize) != 0)
                                break;
                        p -= VtScoreSize;
                }
                return p - buf;
        }
}