MIPS Tutorial 6 Printing a Float

Summary

This tutorial provides a step-by-step guide on how to print a float in assembly language, using the value of Pi (3.14) as an example. It explains how floats differ from integers, including how to load a float into the appropriate register (Coprocessor 1) and print it using system calls. The video demonstrates the key assembly commands needed, such as `load word` for floats and proper register usage like `F12`. The tutorial concludes with an encouragement to subscribe and a preview of the next lesson on doubles.

Takeaways

• 😀 A float is a decimal number with up to six decimal places of precision.
• 😀 To declare a float in assembly, use the `.float` directive followed by the value.
• 😀 The value `3.14` is commonly used as an example for the float variable 'Pi'.
• 😀 The code for printing integers in MIPS is `1`, but for printing floats, it's `2`.
• 😀 Floats in MIPS are handled by coprocessor 1 (C1) registers, not general-purpose registers.
• 😀 The float value needs to be loaded into register `F12` before printing it.
• 😀 The `l.s` instruction is used to load a float from memory into the `F12` register.
• 😀 To print the float, use the system call with the code `2` after loading the value into `F12`.
• 😀 The `syscall` instruction triggers the system call to print the float value.
• 😀 MIPS assembly for printing a float involves loading the float into `F12`, then calling the syscall.
• 😀 The tutorial will cover doubles in the next lesson, building on the knowledge of floats.

Q & A

What is a float in programming?

A float is a data type that represents decimal numbers. In MIPS assembly, floats have a precision of six digits after the decimal point.

How do you declare a float in MIPS assembly?

To declare a float in MIPS assembly, use the `.float` directive, followed by the value. For example, `Pi: .float 3.14` declares a float named 'Pi' with the value 3.14.

What is the significance of the number 3.14 in the context of the tutorial?

The number 3.14 is used as an example to represent the mathematical constant Pi, which is often used to demonstrate working with floating-point numbers.

How does MIPS handle floating-point numbers differently from integers?

MIPS handles floating-point numbers using Coprocessor 1 (C1), which has dedicated registers for floating-point operations. In contrast, integers are handled by the main processor with regular registers.

What is the system call code for printing an integer in MIPS?

The system call code for printing an integer in MIPS is `1`.

What is the system call code for printing a float in MIPS?

The system call code for printing a float in MIPS is `2`.

Why is it necessary to load the float into register F12?

In MIPS, floating-point numbers must be loaded into Coprocessor 1 registers, specifically register F12, before they can be printed or manipulated.

How does the process of loading a float differ from loading an integer in MIPS?

To load a float, you use the `lwc1` instruction (load word to Coprocessor 1), whereas for integers, you use the `lw` instruction to load data into general-purpose registers.

What will happen if you forget to load the float value into F12?

If you forget to load the float value into F12, the program will not be able to print the float correctly, as the system call requires the value to be in F12 for processing.

What is the expected output of the program in this tutorial?

The expected output of the program is `3.14`, as the value of the float `Pi` is printed to the screen.