int nBuf;
  int nBufAlloc;
};
typedef struct Buffer Buffer;
static int  thBufferWrite(Th_Interp *interp, Buffer *, const char *, int);
static void thBufferInit(Buffer *);
static void thBufferFree(Th_Interp *interp, Buffer *);

/*
** This version of memcpy() allows the first are second argument to
** be NULL as long as the number of bytes to copy is zero.
*/
static void *th_memcpy(void *dest, const void *src, size_t n){
  return n>0 ? memcpy(dest,src,n) : dest;
}

/*
** Append nAdd bytes of content copied from zAdd to the end of buffer
** pBuffer. If there is not enough space currently allocated, resize
** the allocation to make space.
*/
static int thBufferWrite(

  if( nReq>pBuffer->nBufAlloc ){
    char *zNew;
    int nNew;

    nNew = nReq*2;
    zNew = (char *)Th_Malloc(interp, nNew);
    th_memcpy(zNew, pBuffer->zBuf, pBuffer->nBuf);
    Th_Free(interp, pBuffer->zBuf);
    pBuffer->nBufAlloc = nNew;
    pBuffer->zBuf = zNew;
  }

  th_memcpy(&pBuffer->zBuf[pBuffer->nBuf], zAdd, nAdd);
  pBuffer->nBuf += nAdd;
  pBuffer->zBuf[pBuffer->nBuf] = '\0';

  return TH_OK;
}
#define thBufferWrite(a,b,c,d) thBufferWrite(a,b,(const char *)c,d)

    char **azElem = Th_Malloc(interp,
      sizeof(char*) * nCount +       /* azElem */
      sizeof(int) * nCount +         /* anElem */
      strbuf.nBuf                    /* space for list element strings */
    );
    anElem = (int *)&azElem[nCount];
    zElem = (char *)&anElem[nCount];
    th_memcpy(anElem, lenbuf.zBuf, lenbuf.nBuf);
    th_memcpy(zElem, strbuf.zBuf, strbuf.nBuf);
    for(i=0; i<nCount;i++){
      azElem[i] = zElem;
      zElem += (anElem[i] + 1);
    }
    *pazElem = azElem;
    *panElem = anElem;
  }

    Th_Free(interp, pValue->zData);
    pValue->zData = 0;
  }

  assert(zValue || nValue==0);
  pValue->zData = Th_Malloc(interp, nValue+1);
  pValue->zData[nValue] = '\0';
  th_memcpy(pValue->zData, zValue, nValue);
  pValue->nData = nValue;

  return TH_OK;
}

/*
** Create a variable link so that accessing variable (zLocal, nLocal) is

*/
char *th_strdup(Th_Interp *interp, const char *z, int n){
  char *zRes;
  if( n<0 ){
    n = th_strlen(z);
  }
  zRes = Th_Malloc(interp, n+1);
  th_memcpy(zRes, z, n);
  zRes[n] = '\0';
  return zRes;
}

/*
** Argument zPre must be a nul-terminated string. Set the interpreter
** result to a string containing the contents of zPre, followed by

  if( n<0 ){
    n = th_strlen(z);
  }

  if( z && n>0 ){
    char *zResult;
    zResult = Th_Malloc(pInterp, n+1);
    th_memcpy(zResult, z, n);
    zResult[n] = '\0';
    pInterp->zResult = zResult;
    pInterp->nResult = n;
  }

  return TH_OK;
}

  if( nElem<0 ){
    nElem = th_strlen(zElem);
  }

  nNew = *pnStr + nElem;
  zNew = Th_Malloc(interp, nNew);
  th_memcpy(zNew, *pzStr, *pnStr);
  th_memcpy(&zNew[*pnStr], zElem, nElem);

  Th_Free(interp, *pzStr);
  *pzStr = zNew;
  *pnStr = nNew;

  return TH_OK;
}

      }

      if( pNew->pOp || pNew->nValue ){
        if( pNew->nValue ){
          /* A terminal. Copy the string value. */
          assert( !pNew->pOp );
          pNew->zValue = Th_Malloc(interp, pNew->nValue);
          th_memcpy(pNew->zValue, z, pNew->nValue);
          i += pNew->nValue;
        }
        if( (nToken%16)==0 ){
          /* Grow the apToken array. */
          Expr **apTokenOld = apToken;
          apToken = Th_Malloc(interp, sizeof(Expr *)*(nToken+16));
          th_memcpy(apToken, apTokenOld, sizeof(Expr *)*nToken);
        }

        /* Put the new token at the end of the apToken array */
        apToken[nToken] = pNew;
        nToken++;
      }else{
        Th_Free(interp, pNew);

    pRet = 0;
  }

  if( op>0 && !pRet ){
    pRet = (Th_HashEntry *)Th_Malloc(interp, sizeof(Th_HashEntry) + nKey);
    pRet->zKey = (char *)&pRet[1];
    pRet->nKey = nKey;
    th_memcpy(pRet->zKey, zKey, nKey);
    pRet->pNext = pHash->a[iKey];
    pHash->a[iKey] = pRet;
  }

  return pRet;
}