Step by Step solution about How to resolve the algorithm Create an object at a given address step by step in the C programming language

First Code Snippet:

This code snippet demonstrates memory access and manipulation in C using pointers.

• It declares two variables: intspace, an integer, and address, a pointer to an integer.
• It assigns the address of intspace to the pointer address (effectively address = &intspace).
• It stores the value 65535 in the memory location pointed to by address (i.e., in intspace).
• It prints the address, the value stored at the address, and the value of intspace.
• It then manipulates the memory directly using pointer arithmetic to change the value stored in intspace. Specifically, it sets the first two bytes to 0x00 and the last two bytes to 0xFF.
• It prints the address, the value stored at the address, and the value of intspace again.

Second Code Snippet:

This code snippet demonstrates memory access and manipulation in C using a memory-mapped I/O register.

• It includes the headers <stdint.h> and <stddef.h> to access the uint32_t data type and size_t for pointer arithmetic.
• It defines a preprocessor macro PORT_A that points to a volatile 32-bit unsigned integer at memory address 0x100.
• It toggles the 0th bit of the register PORT_A by XORing it with 0x01.
• It reads the value of PORT_A into the variable dat.
• It calculates the address of PORT_A using the & operator and stores it in the variable addr.

This snippet essentially allows you to access and manipulate hardware registers through a pointer-like interface, a common technique in embedded systems programming.

#include <stdio.h>

int main()
{
  int intspace;
  int *address;

  address = &intspace; // address = 0x100;
  *address = 65535;
  printf("%p: %08x (=%08x)\n", address, *address, intspace);
  // likely we must be worried about endianness, e.g.
  *((char*)address) = 0x00;
  *((char*)address+1) = 0x00;
  *((char*)address+2) = 0xff;
  *((char*)address+3) = 0xff; // if sizeof(int) == 4!
  // which maybe is not the best way of writing 32 bit values...
  printf("%p: %08x (=%08x)\n", address, *address, intspace);
  return 0;
}


#include <stdint.h>
#include <stddef.h>

// This is a port variable located at address 0x100
#define PORT_A (*(volatile uint32_t*)0x100)

int main()
{
  uint32_t dat;
  size_t addr;

  PORT_A ^= 0x01;   // Toggle bit 0 of PORT_A
  dat = PORT_A;     // Read PORT_A
  addr = &PORT_A;   // addr = 0x100

  return 0;
}