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#include <u.h>
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#include <libc.h>
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#include <oventi.h>
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/* score of a zero length block */
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uchar	vtZeroScore[VtScoreSize] = {
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	0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d, 0x32, 0x55,
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	0xbf, 0xef, 0x95, 0x60, 0x18, 0x90, 0xaf, 0xd8, 0x07, 0x09
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};
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int
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vtZeroExtend(int type, uchar *buf, int n, int nn)
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{
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	uchar *p, *ep;
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	switch(type) {
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	default:
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		memset(buf+n, 0, nn-n);
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		break;
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	case VtPointerType0:
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	case VtPointerType1:
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	case VtPointerType2:
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	case VtPointerType3:
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	case VtPointerType4:
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	case VtPointerType5:
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	case VtPointerType6:
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	case VtPointerType7:
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	case VtPointerType8:
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	case VtPointerType9:
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		p = buf + (n/VtScoreSize)*VtScoreSize;
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		ep = buf + (nn/VtScoreSize)*VtScoreSize;
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		while(p < ep) {
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			memmove(p, vtZeroScore, VtScoreSize);
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			p += VtScoreSize;
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		}
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		memset(p, 0, buf+nn-p);
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		break;
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	}
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	return 1;
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}
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int
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vtZeroTruncate(int type, uchar *buf, int n)
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{
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	uchar *p;
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	switch(type) {
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	default:
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		for(p = buf + n; p > buf; p--) {
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			if(p[-1] != 0)
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				break;
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		}
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		return p - buf;
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	case VtRootType:
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		if(n < VtRootSize)
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			return n;
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		return VtRootSize;
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	case VtPointerType0:
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	case VtPointerType1:
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	case VtPointerType2:
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	case VtPointerType3:
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	case VtPointerType4:
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	case VtPointerType5:
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	case VtPointerType6:
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	case VtPointerType7:
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	case VtPointerType8:
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	case VtPointerType9:
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		/* ignore slop at end of block */
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		p = buf + (n/VtScoreSize)*VtScoreSize;
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		while(p > buf) {
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			if(memcmp(p - VtScoreSize, vtZeroScore, VtScoreSize) != 0)
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				break;
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			p -= VtScoreSize;
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		}
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		return p - buf;
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	}
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}