MemoryFunctions.cpp File Reference

implements of function which deals with memory More...

#include "stdafx.h"
#include "MemoryFunctions.h"
#include <stdio.h>
#include <stdlib.h>

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Functions
void	fillarray (void *p, void *value, size_t size, size_t n)
	This function assigns the specified value to each element. More...
void	fillzero (void *p, size_t n)
	This function fills a block of memory zeros. More...
bool	isbigendian ()
	judges whether the system is big endian More...
bool	islittleendian ()
	gets the system is little endian More...
void	memreverse (void *p, size_t n)
	reverse memory (ex. Big Endian <-> Little Endian) More...
void	memswap (void *p0, void *p1, size_t n)
	swaps memory ( p0 <-> p1 ) More...

Detailed Description

implements of function which deals with memory

Author

S.Tanaka

Date

2006.07.13

Copyright(C) 2006-2014 Eisai Co., Ltd. All rights reserved.

Definition in file MemoryFunctions.cpp.

Function Documentation

void fillarray	(	void *	p,
		void *	value,
		size_t	size,
		size_t	n
	)

This function assigns the specified value to each element.

Parameters

[out]	p	array
[in]	value	specified value
[in]	size	size of element
[in]	n	size of array

Definition at line 20 of file MemoryFunctions.cpp.

                                                              {
    // void* -> char* (because void* doesn't have the size of element)
    char* cp = (char*)p;
    char* cv = (char*)value;

    // fill
    for( unsigned int i = 0; i < n; i++ ) {
        char* p_i = cp + ( size * i );
        for( unsigned int j = 0; j < size; j++ ) {
            p_i[ j ] = cv[ j ];
        }
    }
}

void fillzero	(	void *	p,
		size_t	n
	)

This function fills a block of memory zeros.

Parameters

[out]	p	pointer to starting addres of the block of memory to fill with zeros.
[in]	n	size of the block of memory to fill with zeros.

Definition at line 35 of file MemoryFunctions.cpp.

                                   {
    unsigned char zero = 0;

    fillarray( p, &zero, 1, n );
}

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bool isbigendian

(

)

judges whether the system is big endian

Returns

If the system is big endian, this function returns true.

Definition at line 42 of file MemoryFunctions.cpp.

                   {
    // create 2 bytes data
    short num = 1;  // (Big: 00 01,  Little: 01 00)

    // get first byte
    char* c = (char*)#

    return ( *c == 0 );
}

bool islittleendian

(

)

gets the system is little endian

Returns

If the system is little endian, this function returns true.

Definition at line 53 of file MemoryFunctions.cpp.

                      {
    return !isbigendian();
}

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void memreverse	(	void *	p,
		size_t	n
	)

reverse memory (ex. Big Endian <-> Little Endian)

Parameters

[in,out]	p	the address of memory
[in]	n	memory size

Definition at line 58 of file MemoryFunctions.cpp.

                                     {
    // check parameters
    if( p == NULL || n == 0 ) {
        return;
    }

    // create buffer
    char* buffer = new char[ n ];

    // copy to buffer
    memcpy( buffer, p, n );

    // reverse
    char* cp = (char*)p;
    for( unsigned int i = 0; i < n; i++ ) {
        cp[ i ] = buffer[ n - 1 - i ];
    }

    // delete
    delete[] buffer;
}

void memswap	(	void *	p0,
		void *	p1,
		size_t	n
	)

swaps memory ( p0 <-> p1 )

Parameters

[in,out]	p0	the address of memory to be swapped
[in,out]	p1	the address of memory to swap
[in]	n	memory size

Definition at line 81 of file MemoryFunctions.cpp.

                                             {
    // check parameters
    if( p0 == NULL || p1 == NULL || n == 0 ) {
        return;
    }

    // create buffer
    void* tmp = malloc( n );

    // copy
    memcpy( tmp, p0, n );
    memcpy( p0, p1, n );
    memcpy( p1, tmp, n );

    // free
    free( tmp );
}