Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference

ID 790148
Date 3/22/2024
Public

A newer version of this document is available.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

Document Table of Contents

DecodeLZOSafe

Decompresses input data with constantly checking integrity of output.

Syntax

IppStatus ippsDecodeLZOSafe_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

This function is a version of the function ippsDecodeLZO. It decompresses the source (compressed) data according to the compressed data format. The function can decompress both single-thread and multi-threaded data. The maximum performance can be obtained only in multi-threaded decompression of data compressed in the multi-threaded mode. Additionally this function checks the integrity of the destination data buffer, that is checks the buffer boundary limits. This function works slower, it can be used in doubtful cases when the compressed data integrity is not guaranteed, for example, decoding data received via non-reliable communication lines.

Destination data buffer must have enough free space to hold uncompressed data. Prior to the function call the destination buffer size variable pointed to by pDstLen must be initialized with actual number of free bytes in the destination buffer.

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

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

ippStsLzoBrokenStreamErr

Indicates an error if compressed data is not valid - not an LZO compressed data.

ippStsDstSizeLessExpected

Destination buffer is too small to store decompressed data.

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 Performance 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;
}