Intel® Integrated Performance Primitives Developer Guide and Reference

ID 790148
Date 11/07/2023
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

DecodeLZO

Decompresses input data, returns the length of the decompressed data.

Syntax

IppStatus ippsDecodeLZO_8u (const Ipp8u* pSrc, Ipp32u srcLen, Ipp8u* pDst, Ipp32u* pDstLen);

Include Files

ippdc.h

Domain Dependencies

Headers: ippcore.h, ippvm.h, ipps.h

Libraries: ippcore.lib, ippvm.lib, ipps.lib

Parameters

pSrc

Pointer to the source data buffer.

srcLen

Number of elements in the source data buffer.

pDst

Pointer to the destination data buffer.

pDstLen

Pointer to the variable with the number of elements in the destination data buffer.

Description

The function decompresses the source (compressed) data according to the compressed data format. This function can decompress both single-thread and multi-threaded data. Note that the maximum performance can be obtained only in multi-threaded decompression of data compressed in the multi-threaded mode.

NOTE:

Destination data buffer must have enough free space to hold uncompressed data. No output buffer check is performed and no error code is returned. In the case of doubts use safe version of this function DecodeLZOSafe .

Code example shows how the Intel IPP functions for the LZO compression can be used.

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

Indicates an error if one of the specified pointers is NULL.

Example

/*******************************************************************************
* Copyright 2017 Intel Corporation.
*
*
* This software and the related documents are Intel copyrighted materials, and your use of them is governed by
* the express license under which they were provided to you ('License'). Unless the License provides otherwise,
* you may not use, modify, copy, publish, distribute, disclose or transmit this software or the related
* documents without Intel's prior written permission.
* This software and the related documents are provided as is, with no express or implied warranties, other than
* those that are expressly stated in the License.
*******************************************************************************/

/*
 The example below shows how to use the functions:
        ippsEncodeLZOGetSize
        ippsEncodeLZO_8u
        ippsEncodeLZOInit_8u
        ippsDecodeLZO_8u
        ippsDecodeLZOSafe_8u
*/

#include <stdio.h>
#include <string.h>

#include <ipp/ippdc.h>      /* Data compression functions       */
#include <ipp/ipps.h>       /* Malloc/vector initialization function   */

/* Next two defines are created to simplify code reading and understanding          */
#define EXIT_MAIN       exitLine:                              /* Label for Exit    */
#define check_sts(st)   if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) Integrated Primitives (Intel(R) IPP) function returned status different from ippStsNoErr */

#define TEST_SIZE (1024 * 4)
#define DECOMPR_MAX (TEST_SIZE + 64)

int main(void)
{
    Ipp8u           *srcBuf = NULL, *comprBuf = NULL, *decomprBuf = NULL;
    IppStatus       st;
    int             i;
    Ipp32u          stateSize;
    IppLZOState_8u  *lzoState = NULL;
    Ipp32u          comprLen, decomprLen;

    /* Allocate buffers */
    srcBuf      = ippsMalloc_8u(TEST_SIZE);
    decomprBuf  = ippsMalloc_8u(DECOMPR_MAX);    /* Extra 64 bytes may be required
                                                       for non-safe decompression       */
    comprBuf    = ippsMalloc_8u(TEST_SIZE + TEST_SIZE/10);
    /* Initialize source buffer */
    check_sts(  st = ippsVectorJaehne_8u(srcBuf, TEST_SIZE, IPP_MAX_8U)         )
    for(i = 0; i < TEST_SIZE; i++)
        srcBuf[i] >>= 6;                                /* Decrease source data entropy */
    /* Allocate and initialize LZO structure */
    check_sts(  st = ippsEncodeLZOGetSize(IppLZO1XST, TEST_SIZE, &stateSize)    )
    lzoState = (IppLZOState_8u*)ippsMalloc_8u(stateSize);
    check_sts(  st = ippsEncodeLZOInit_8u(IppLZO1XST, TEST_SIZE, lzoState)      )
    /* LZO compress, decompress and compare */
    comprLen = (TEST_SIZE + TEST_SIZE/10);
    check_sts(  st = ippsEncodeLZO_8u(srcBuf, TEST_SIZE, comprBuf, &comprLen, lzoState)   )
    printf("LZO compress: %d bytes compressed into %d bytes\n", TEST_SIZE, (int)comprLen);
    decomprLen = DECOMPR_MAX;
    check_sts(  st = ippsDecodeLZO_8u(comprBuf, comprLen, decomprBuf, &decomprLen)    )
    if(decomprLen != TEST_SIZE || memcmp(decomprBuf, srcBuf, TEST_SIZE) != 0)
    {
        printf("Non-safe decompress failed!\n");
        st = ippStsErr;
        goto exitLine;
    }
    else
        printf("Non-safe decompress verified.\n");
    /* Decompress using safe function */
    ippsZero_8u(decomprBuf, DECOMPR_MAX);
    decomprLen = TEST_SIZE;                         /* Can specify exact size */
    check_sts(  st = ippsDecodeLZOSafe_8u(comprBuf, comprLen, decomprBuf, &decomprLen)  )
    if(decomprLen != TEST_SIZE || memcmp(decomprBuf, srcBuf, TEST_SIZE) != 0)
    {
        printf("Safe decompress failed!\n");
        st = ippStsErr;
        goto exitLine;
    }
    else
        printf("Safe decompress verified.\n");

EXIT_MAIN
    ippsFree(srcBuf);
    ippsFree(decomprBuf);
    ippsFree(comprBuf);
    ippsFree(lzoState);
    return (int)st;
}