memoryIO.h File Reference

Defines classes for memory input and output operations of various bit widths (8, 16, 32, 64 bits). More...

#include <cstdint>
#include <cstddef>

Go to the source code of this file.

Classes
class	MaxOS::memory::MemIO
	base class for all memory IO More...
class	MaxOS::memory::MemIO8Bit
	Handles 8 bit memory IO. More...
class	MaxOS::memory::MemIO16Bit
	Handles 16 bit memory IO. More...
class	MaxOS::memory::MemIO32Bit
	Handles 32 bit memory IO. More...
class	MaxOS::memory::MemIO64Bit
	Handles 64 bit memory IO. More...

Functions
void *	memcpy (void *destination, const void *source, uint64_t num)
	Copies a block of memory from one location to another.
void *	memset (void *ptr, uint32_t value, uint64_t num)
	Fills a block of memory with a specified value.
void *	memmove (void *destination, const void *source, uint64_t num)
	Copies a block of memory from one location to another.
int	memcmp (const void *ptr1, const void *ptr2, uint64_t num)
	Compares two blocks of memory.

Detailed Description

Defines classes for memory input and output operations of various bit widths (8, 16, 32, 64 bits).

Date

29th November 2022

Author

Max Tyson

Definition in file memoryIO.h.

Function Documentation

memcmp()

int memcmp	(	const void *	ptr1,
		const void *	ptr2,
		uint64_t	num
	)

Compares two blocks of memory.

Parameters

ptr1	The m_first_memory_chunk block of memory
ptr2	The second block of memory
num	The number of bytes to compare

Returns

0 if the blocks of memory are equal, -1 if ptr1 < ptr2, 1 if ptr1 > ptr2

Definition at line 265 of file memoryIO.cpp.

                                                             {
 
    // Make sure the pointers exist
    if (ptr1 == nullptr || ptr2 == nullptr)
        return 0;
 
    const auto* p1 = (const unsigned char*) ptr1;
    const auto* p2 = (const unsigned char*) ptr2;
    for (size_t i = 0; i < num; i++) {
        if (p1[i] < p2[i])
            return -1;
        if (p1[i] > p2[i])
            return 1;
    }
    return 0;
}

memcpy()

void * memcpy	(	void *	destination,
		const void *	source,
		uint64_t	num
	)

Copies a block of memory from one location to another.

See also

https://wiki.osdev.org/Meaty_Skeleton#memcpy.28.29

Parameters

destination	The destination to copy to
source	The source to copy from
num	The number of bytes to copy

Returns

The destination

Definition at line 165 of file memoryIO.cpp.

                                                                  {
 
    // Make sure the source and destination are not the same
    if (destination == source)
        return destination;
 
    // Make sure they exist
    if (destination == nullptr || source == nullptr)
        return destination;
 
    // Get the source and destination
    auto* dst = (unsigned char*) destination;
    const auto* src = (const unsigned char*) source;
 
    // Copy the data
    for (size_t i = 0; i < num; i++)
        dst[i] = src[i];
 
    // Usefully for easier code writing
    return destination;
}

Referenced by MaxOS::common::Buffer::copy_from(), MaxOS::common::Buffer::copy_from(), MaxOS::common::Buffer::copy_to(), MaxOS::common::Buffer::copy_to(), MaxOS::processes::SharedMessageEndpoint::read(), MaxOS::common::Buffer::resize(), and MaxOS::processes::Thread::Thread().

memmove()

void * memmove	(	void *	destination,
		const void *	source,
		uint64_t	num
	)

Copies a block of memory from one location to another.

Parameters

destination	The destination to copy to
source	The source to copy from
num	The number of bytes to copy

Returns

The destination

Definition at line 235 of file memoryIO.cpp.

                                                                   {
 
    // Make sure the source and destination are not the same
    if (destination == source)
        return destination;
 
    // Make sure they exist
    if (destination == nullptr || source == nullptr)
        return destination;
 
    auto* dst = (unsigned char*) destination;
    const auto* src = (const unsigned char*) source;
    if (dst < src) {
        for (size_t i = 0; i < num; i++)
            dst[i] = src[i];
    } else {
        for (size_t i = num; i != 0; i--)
            dst[i - 1] = src[i - 1];
    }
    return destination;
}

Referenced by MaxOS::drivers::console::VESABootConsole::scroll_up().

memset()

void * memset	(	void *	ptr,
		uint32_t	value,
		uint64_t	num
	)

Fills a block of memory with a specified value.

Parameters

ptr	The pointer to the block of memory
value	The value to fill the block of memory with
num	The number of bytes to fill

Returns

The pointer to the block of memory

Definition at line 215 of file memoryIO.cpp.

                                                      {
 
    // Make sure the pointer exists
    if (ptr == nullptr)
        return ptr;
 
    auto* dst = (uint32_t*) ptr;
    for (size_t i = 0; i < num; i++)
        dst[i] = value;
    return ptr;
}

Referenced by MaxOS::common::Buffer::clear(), MaxOS::common::Buffer::full(), and MaxOS::drivers::console::VESABootConsole::print_logo().