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262 lines
9.1 KiB
262 lines
9.1 KiB
Description: Handle unaligned buffers in connect's TYPBLK class
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On MIPS platforms (and probably others) unaligned memory access results in a
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bus error. In the connect storage engine, block data for some data formats is
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stored packed in memory and the TYPBLK class is used to read values from it.
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Since TYPBLK does not have special handling for this packed memory, it can
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quite easily result in unaligned memory accesses.
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.
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The simple way to fix this is to perform all accesses to the main buffer
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through memcpy. With GCC and optimizations turned on, this call to memcpy is
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completely optimized away on architectures where unaligned accesses are ok
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(like x86).
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Author: James Cowgill <jcowgill@debian.org>
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---
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This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
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--- a/storage/connect/valblk.h
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+++ b/storage/connect/valblk.h
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@@ -139,6 +139,7 @@ class VALBLK : public BLOCK {
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int Prec; // Precision of float values
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}; // end of class VALBLK
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+
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/***********************************************************************/
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/* Class TYPBLK: represents a block of typed values. */
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/***********************************************************************/
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@@ -151,40 +152,41 @@ class TYPBLK : public VALBLK {
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// Implementation
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virtual bool Init(PGLOBAL g, bool check);
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virtual int GetVlen(void) {return sizeof(TYPE);}
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- virtual char GetTinyValue(int n) {return (char)Typp[n];}
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- virtual uchar GetUTinyValue(int n) {return (uchar)Typp[n];}
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- virtual short GetShortValue(int n) {return (short)Typp[n];}
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- virtual ushort GetUShortValue(int n) {return (ushort)Typp[n];}
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- virtual int GetIntValue(int n) {return (int)Typp[n];}
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- virtual uint GetUIntValue(int n) {return (uint)Typp[n];}
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- virtual longlong GetBigintValue(int n) {return (longlong)Typp[n];}
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- virtual ulonglong GetUBigintValue(int n) {return (ulonglong)Typp[n];}
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- virtual double GetFloatValue(int n) {return (double)Typp[n];}
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+
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+ virtual char GetTinyValue(int n) {return (char)UnalignedRead(n);}
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+ virtual uchar GetUTinyValue(int n) {return (uchar)UnalignedRead(n);}
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+ virtual short GetShortValue(int n) {return (short)UnalignedRead(n);}
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+ virtual ushort GetUShortValue(int n) {return (ushort)UnalignedRead(n);}
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+ virtual int GetIntValue(int n) {return (int)UnalignedRead(n);}
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+ virtual uint GetUIntValue(int n) {return (uint)UnalignedRead(n);}
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+ virtual longlong GetBigintValue(int n) {return (longlong)UnalignedRead(n);}
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+ virtual ulonglong GetUBigintValue(int n) {return (ulonglong)UnalignedRead(n);}
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+ virtual double GetFloatValue(int n) {return (double)UnalignedRead(n);}
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virtual char *GetCharString(char *p, int n);
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- virtual void Reset(int n) {Typp[n] = 0;}
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+ virtual void Reset(int n) {UnalignedWrite(n, 0);}
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// Methods
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using VALBLK::SetValue;
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virtual void SetValue(PCSZ sp, int n);
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virtual void SetValue(const char *sp, uint len, int n);
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virtual void SetValue(short sval, int n)
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- {Typp[n] = (TYPE)sval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)sval); SetNull(n, false);}
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virtual void SetValue(ushort sval, int n)
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- {Typp[n] = (TYPE)sval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)sval); SetNull(n, false);}
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virtual void SetValue(int lval, int n)
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- {Typp[n] = (TYPE)lval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)lval); SetNull(n, false);}
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virtual void SetValue(uint lval, int n)
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- {Typp[n] = (TYPE)lval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)lval); SetNull(n, false);}
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virtual void SetValue(longlong lval, int n)
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- {Typp[n] = (TYPE)lval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)lval); SetNull(n, false);}
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virtual void SetValue(ulonglong lval, int n)
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- {Typp[n] = (TYPE)lval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)lval); SetNull(n, false);}
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virtual void SetValue(double fval, int n)
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- {Typp[n] = (TYPE)fval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)fval); SetNull(n, false);}
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virtual void SetValue(char cval, int n)
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- {Typp[n] = (TYPE)cval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)cval); SetNull(n, false);}
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virtual void SetValue(uchar cval, int n)
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- {Typp[n] = (TYPE)cval; SetNull(n, false);}
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+ {UnalignedWrite(n, (TYPE)cval); SetNull(n, false);}
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virtual void SetValue(PVAL valp, int n);
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virtual void SetValue(PVBLK pv, int n1, int n2);
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virtual void SetMin(PVAL valp, int n);
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@@ -206,6 +208,17 @@ class TYPBLK : public VALBLK {
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// Members
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TYPE* const &Typp;
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const char *Fmt;
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+
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+ // Unaligned access
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+ TYPE UnalignedRead(int n) const {
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+ TYPE result;
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+ memcpy(&result, Typp + n, sizeof(TYPE));
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+ return result;
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+ }
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+
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+ void UnalignedWrite(int n, TYPE value) {
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+ memcpy(Typp + n, &value, sizeof(TYPE));
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+ }
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}; // end of class TYPBLK
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/***********************************************************************/
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--- a/storage/connect/valblk.cpp
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+++ b/storage/connect/valblk.cpp
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@@ -266,14 +266,14 @@ bool TYPBLK<TYPE>::Init(PGLOBAL g, bool
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template <class TYPE>
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char *TYPBLK<TYPE>::GetCharString(char *p, int n)
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{
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- sprintf(p, Fmt, Typp[n]);
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+ sprintf(p, Fmt, UnalignedRead(n));
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return p;
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} // end of GetCharString
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template <>
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char *TYPBLK<double>::GetCharString(char *p, int n)
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{
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- sprintf(p, Fmt, Prec, Typp[n]);
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+ sprintf(p, Fmt, Prec, UnalignedRead(n));
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return p;
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} // end of GetCharString
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@@ -289,7 +289,7 @@ void TYPBLK<TYPE>::SetValue(PVAL valp, i
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ChkTyp(valp);
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if (!(b = valp->IsNull()))
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- Typp[n] = GetTypedValue(valp);
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+ UnalignedWrite(n, GetTypedValue(valp));
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else
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Reset(n);
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@@ -351,9 +351,9 @@ void TYPBLK<TYPE>::SetValue(PCSZ p, int
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ulonglong val = CharToNumber(p, strlen(p), maxval, Unsigned, &minus);
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if (minus && val < maxval)
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- Typp[n] = (TYPE)(-(signed)val);
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+ UnalignedWrite(n, (TYPE)(-(signed)val));
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else
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- Typp[n] = (TYPE)val;
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+ UnalignedWrite(n, (TYPE)val);
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SetNull(n, false);
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} // end of SetValue
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@@ -396,7 +396,7 @@ void TYPBLK<double>::SetValue(PCSZ p, in
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throw Type;
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} // endif Check
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- Typp[n] = atof(p);
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+ UnalignedWrite(n, atof(p));
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SetNull(n, false);
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} // end of SetValue
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@@ -428,7 +428,7 @@ void TYPBLK<TYPE>::SetValue(PVBLK pv, in
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ChkTyp(pv);
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if (!(b = pv->IsNull(n2) && Nullable))
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- Typp[n1] = GetTypedValue(pv, n2);
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+ UnalignedWrite(n1, GetTypedValue(pv, n2));
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else
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Reset(n1);
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@@ -479,10 +479,10 @@ void TYPBLK<TYPE>::SetMin(PVAL valp, int
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{
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CheckParms(valp, n)
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TYPE tval = GetTypedValue(valp);
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- TYPE& tmin = Typp[n];
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+ TYPE tmin = UnalignedRead(n);
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if (tval < tmin)
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- tmin = tval;
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+ UnalignedWrite(n, tval);
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} // end of SetMin
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@@ -494,10 +494,10 @@ void TYPBLK<TYPE>::SetMax(PVAL valp, int
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{
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CheckParms(valp, n)
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TYPE tval = GetTypedValue(valp);
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- TYPE& tmin = Typp[n];
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+ TYPE tmin = UnalignedRead(n);
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if (tval > tmin)
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- tmin = tval;
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+ UnalignedWrite(n, tval);
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} // end of SetMax
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@@ -511,8 +511,7 @@ void TYPBLK<TYPE>::SetValues(PVBLK pv, i
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CheckType(pv)
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TYPE *lp = ((TYPBLK*)pv)->Typp;
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- for (register int i = k; i < n; i++) // TODO
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- Typp[i] = lp[i];
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+ memcpy(Typp + k, lp + k, sizeof(TYPE) * n);
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} // end of SetValues
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#endif // 0
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@@ -523,7 +522,7 @@ void TYPBLK<TYPE>::SetValues(PVBLK pv, i
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template <class TYPE>
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void TYPBLK<TYPE>::Move(int i, int j)
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{
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- Typp[j] = Typp[i];
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+ UnalignedWrite(j, UnalignedRead(i));
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MoveNull(i, j);
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} // end of Move
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@@ -537,7 +536,7 @@ int TYPBLK<TYPE>::CompVal(PVAL vp, int n
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ChkIndx(n);
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ChkTyp(vp);
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#endif // _DEBUG
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- TYPE mlv = Typp[n];
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+ TYPE mlv = UnalignedRead(n);
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TYPE vlv = GetTypedValue(vp);
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return (vlv > mlv) ? 1 : (vlv < mlv) ? (-1) : 0;
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@@ -549,8 +548,8 @@ int TYPBLK<TYPE>::CompVal(PVAL vp, int n
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template <class TYPE>
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int TYPBLK<TYPE>::CompVal(int i1, int i2)
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{
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- TYPE lv1 = Typp[i1];
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- TYPE lv2 = Typp[i2];
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+ TYPE lv1 = UnalignedRead(i1);
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+ TYPE lv2 = UnalignedRead(i2);
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return (lv1 > lv2) ? 1 : (lv1 < lv2) ? (-1) : 0;
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} // end of CompVal
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@@ -587,7 +586,7 @@ int TYPBLK<TYPE>::Find(PVAL vp)
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TYPE n = GetTypedValue(vp);
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for (i = 0; i < Nval; i++)
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- if (n == Typp[i])
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+ if (n == UnalignedRead(i))
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break;
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return (i < Nval) ? i : (-1);
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@@ -603,7 +602,7 @@ int TYPBLK<TYPE>::GetMaxLength(void)
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int i, n, m;
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for (i = n = 0; i < Nval; i++) {
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- m = sprintf(buf, Fmt, Typp[i]);
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+ m = sprintf(buf, Fmt, UnalignedRead(i));
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n = MY_MAX(n, m);
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} // endfor i
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@@ -1333,7 +1332,7 @@ char *DATBLK::GetCharString(char *p, int
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char *vp;
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if (Dvalp) {
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- Dvalp->SetValue(Typp[n]);
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+ Dvalp->SetValue(UnalignedRead(n));
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vp = Dvalp->GetCharString(p);
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} else
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vp = TYPBLK<int>::GetCharString(p, n);
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@@ -1349,7 +1348,7 @@ void DATBLK::SetValue(PCSZ p, int n)
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if (Dvalp) {
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// Decode the string according to format
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Dvalp->SetValue_psz(p);
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- Typp[n] = Dvalp->GetIntValue();
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+ UnalignedWrite(n, Dvalp->GetIntValue());
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} else
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TYPBLK<int>::SetValue(p, n);
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