Improved CS:APP Data Lab

Your goal is to modify your copy of bits.c so that it passes all the tests in btest without violating any of the coding guidelines.

Copyright information

• Copyright (c) 2001-2011, R. Bryant and D. O'Hallaron, All rights reserved.
• Modified by National Cheng Kung University, Taiwan, in 2018.

Files

• Makefile : Makes btest, fshow, and ishow
• README.md : This file
• bits.c : The file you will be modifying and handing in
• bits.h : Header file
• btest.c : The main btest program
  • btest.h : Used to build btest
  • decl.c : Used to build btest
  • tests.c : Used to build btest
• fshow.c : Utility for examining floating-point representations
• ishow.c : Utility for examining integer representations

Testing with btest

The Makefile in this directory compiles your version of bits.c with additional code to create a program (or test harness) named btest.

To compile and run the btest program, type:

$ make btest
$ ./btest [optional cmd line args]

Alternatively, you can use the command to launch btest program, type:

$ make check

Btest tests your code for correctness by running millions of test cases on each function. It tests wide swaths around well known corner cases such as Tmin and zero for integer puzzles, and zero, inf, and the boundary between denormalized and normalized numbers for floating point puzzles. When btest detects an error in one of your functions, it prints out the test that failed, the incorrect result, and the expected result, and then terminates the testing for that function.

Here are the command line options for btest:

$ ./btest -h
Usage: ./btest [-hg] [-r <n>] [-f <name> [-1|-2|-3 <val>]*] [-T <time limit>]
  -1 <val>  Specify first function argument
  -2 <val>  Specify second function argument
  -3 <val>  Specify third function argument
  -f <name> Test only the named function
  -g        Format output for autograding with no error messages
  -h        Print this message
  -r <n>    Give uniform weight of n for all problems
  -T <lim>  Set timeout limit to lim

Examples:

Test all functions for correctness and print out error messages:

$ ./btest

Test all functions in a compact form with no error messages:

$ ./btest -g

Test function foo for correctness:

$ ./btest -f foo

Test function foo for correctness with specific arguments:

$ ./btest -f foo -1 27 -2 0xf

Btest does not check your code for compliance with the coding guidelines.

Helper Programs

We have included the ishow and fshow programs to help you decipher integer and floating point representations respectively. Each takes a single decimal or hex number as an argument. To build them type:

$ make

Example usages:

$ ./ishow 0x27
Hex = 0x00000027,	Signed = 39,	Unsigned = 39

$ ./ishow 27
Hex = 0x0000001b,	Signed = 27,	Unsigned = 27

$ ./fshow 0x15213243
Floating point value 3.255334057e-26
Bit Representation 0x15213243, sign = 0, exponent = 0x2a, fraction = 0x213243
Normalized.  +1.2593463659 X 2^(-85)

$ ./fshow 15213243
Floating point value 2.131829405e-38
Bit Representation 0x00e822bb, sign = 0, exponent = 0x01, fraction = 0x6822bb
Normalized.  +1.8135598898 X 2^(-126)