BWTInv

Performs the inverse BWT transform.

Syntax

IppStatus ippsBWTInv_8u(const Ipp8u* pSrc, Ipp8u* pDst, int len, int index, Ipp8u* pBWTInvBuff);

Parameters

pSrc	Pointer to the source vector.
pDst	Pointer to the destination vector.
len	Number of elements in the source and destination vectors.
index	Index of first position for the inverse BWT transform.
pBWTInvBuff	Pointer to the additional buffer.

Description

The function ippsBWTInv is declared in the ippdc.h file. This function performs the inverse BWT transform of len elements starting from pIndex element of the source vector pSrc and stores result in the vector pDst. The function uses the external buffer pBWTInvBuff. The size of this buffer must be computed by calling the function ippsBWTInvGetSize beforehand.

Example below shows how to use the function ippsBWTInv_8u.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error if one of the specified pointers is NULL.
ippStsSizeErr	Indicates an error if len is less than or equal to 0.

Performing the Burrows-Wheeler Transform

void func_BWT()

    int wndSize = 8;

    int pBWTFwdBuffSize;

    int pBWTInvBuffSize;

    Ipp8u pSrc[] = "baadeffg";

    int len = 8;

    int pIndex;

    Ipp8u* pDst = ippsMalloc_8u(len);

    Ipp8u* pDstInv = ippsMalloc_8u(len);

    ippsBWTFwdGetSize_8u(wndSize, &pBWTFwdBuffSize);

    Ipp8u* pBWTFwdBuff = ippsMalloc_8u(pBWTFwdBuffSize);

    ippsBWTFwd_8u(pSrc, pDst, len, &pIndex, pBWTFwdBuff);

    ippsBWTInvGetSize_8u( wndSize, &pBWTInvBuffSize);

    Ipp8u* pBWTInvBuff = ippsMalloc_8u(pBWTInvBuffSize);

    ippsBWTInv_8u(pDst, pDstInv, len, pIndex, pBWTInvBuff);

Result:

    pDst ->     "bagadeff"

    pDstInv ->  "baadeffg"