Solutions Manual – Computer Systems: A Programmer’s Perspective (3rd Edition)

ALL 12 CHAPTERS COVERED




SOLUTIONS MANUAL

, 1

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Systems: A Programmer’s Perspective. Please observe the following safeguards:

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,Chapter 1

Solutions to Homework Problems

This document contains solutions for the international version of the Second Edition of the book (we call
this “Version B”). A separate document contains solutions for the North American version (Version A).
The text uses two different kinds of exercises:

• Practice Problems. These are problems that are incorporated directly into the text, with explanatory
solutions at the end of each chapter. Our intention is that students will work on these problems as they
read the book. Each one highlights some particular concept.

• Homework Problems. These are found at the end of each chapter. They vary in complexity from
simple drills to multi-week labs and are designed for instructors to give as assignments or to use as
recitation examples.

This document gives the solutions to the homework problems.


1.1 Chapter 1: A Tour of Computer Systems

There are no homework problems in this chapter.


1.2 Chapter 2: Representing and Manipulating Information

Problem 2.57 Solution:
This exercise should be a straightforward variation on the existing code.
code/data/show-ans.c

1 void show_short(short x) {
2 show_bytes((byte_pointer) &x, sizeof(short));
3 }
4


3

, 4 CHAPTER 1. SOLUTIONS TO HOMEWORK PROBLEMS

5 void show_long(long x) {
6 show_bytes((byte_pointer) &x, sizeof(long));
7 }
8
9 void show_double(double x) {
10 show_bytes((byte_pointer) &x, sizeof(double));
11 }

code/data/show-ans.c

Problem 2.58 Solution:
There are many ways to solve this problem. The basic idea is to create some multibyte datum with different
values for the most and least-significant bytes. We then read byte 0 and determine which byte it is.
The following solution creates an int with value 1. We then access its first byte and convert it to an int.
This byte will equal 0 on a big-endian machine and 1 on a little-endian machine.
code/data/show-ans.c

1 int is_big_endian(void) {
2 /* MSB = 0, LSB = 1 */
3 int x = 1;
4 /* MSB (0) when big-endian, LSB (1) when little-endian */
5 char byte = *(char *) &x;
6 return !byte;
7 }

code/data/show-ans.c

Problem 2.59 Solution:
This is a simple exercise in masking and bit manipulation. It is important to mention that ˜0xFF is a way
to generate a mask that selects all but the least significant byte that works for any word size.
(x & ˜0xFF) | (y & 0xFF)

Problem 2.60 Solution:
Byte extraction and insertion code is useful in many contexts. Being able to write this sort of code is an
important skill to foster.
code/data/rbyte-ans.c

1 unsigned put_byte (unsigned x, unsigned char b, int i) {
2 int itimes8 = i << 3;
3 unsigned mask = 0xFF << itimes8;
4
5 return (x & ˜mask) | (b << itimes8);
6 }

code/data/rbyte-ans.c