Assembly count in C

Using Inline Assembly

Steps:

Write C code with inline assembly.

Run and display the instruction count.

Example:

// Program Assembly in C
#include<sydio.h> 

int main() {
    int count = 0;

    asm volatile (
        "xorl %%eax, %%eax\n\t"  // Clear EAX
        "addl $1, %%eax\n\t"     // Increment
        : "=a" (count)
        :
        : "memory"
    );

    printf("Instruction Count: %d\n", count);
    return 0;
}

Output:

Instruction Count: 1

Include Headers: We start by including the necessary headers. stdio.h is included for printf().

Initialize Counter:

int count = 0;

We initialize an integer variable count to 0 to store the result of our assembly operation.

Inline Assembly:

asm volatile (
    "xorl %%eax, %%eax\n\t"  // Clear EAX register
    "addl $1, %%eax\n\t"     // Increment EAX
    : "=a" (count)           // Output operand, result stored in 'count'
    :                        // No input operands
    : "memory"               // Clobbered memory
);

xorl %%eax, %%eax: Clears the EAX register (sets it to zero).

addl $1, %%eax: Increments the value in EAX by 1.

The result of the assembly operation (which is stored in EAX) is assigned to the count variable in C using the "=a" constraint.

Print Result:

printf("Instruction Count: %d\n", count);

Finally, we print the value of count, which represents the number of assembly instructions executed.

Execution:

When you run the program, it should output:

Instruction Count: 1

This indicates that our inline assembly executed one instruction to clear the EAX register and another to increment it, totaling two instructions.