iFloat.h File Reference

Defines interface of iFloat.c functions (do not modify) More...

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Macros
#define	BITS   32
#define	BITS_EXP   8
#define	BITS_MANT   23
#define	EXP_BIAS   127

Typedefs
typedef unsigned int	iFloat_t

Functions
iFloat_t	floatGetSign (iFloat_t x)
iFloat_t	floatGetExp (iFloat_t x)
iFloat_t	floatGetVal (iFloat_t x)
void	floatGetAll (iFloat_t x, iFloat_t *sign, iFloat_t *exp, iFloat_t *val)
iFloat_t	floatLeftMost1 (iFloat_t bits)
iFloat_t	floatAbs (iFloat_t x)
iFloat_t	floatNegate (iFloat_t x)
iFloat_t	floatAdd (iFloat_t x, iFloat_t y)
iFloat_t	floatSub (iFloat_t x, iFloat_t y)

Detailed Description

This file defines the interface to a C file iFloat.c that you will complete. You will learn how to do floating point arithmatic without using any float variables. Rather you will perform the operations by using the sign, exponent, and digit fields as defined in the IEEE floating Point Standard.

Everything in a computer is stored as a series of 0/1's. When you use an int to type a value, you are telling the compiler (and ultimately the CPU) to treat the 0/1's as a two's complement number. When you use float, the 0/1's represent a floating point number. When an addition is performed, the computer knows whether to use the integer or floating point add instruction. The two instruction do different things to the 0/1's.

In this assignment, you are doing floating point operations without using floating point instructions. You are directly doing the bit manipulations necessary to to complete the add. Since iFloat_t is an integer type (short/int), the compiler will generate integer instructions. The iFloat_t is to remind you (the programmer), that although the computer is going to treat all values as integers, you know it is really 3 values (sign, exponent, mantissa) packed into 16/32 bits. Your responsibility is to unpack the three pieces, do the operations necessary to complete the operation, then put the three pieces back together.

Function Documentation

iFloat_t floatAbs

(

iFloat_t

x

)

Absolute value of the argument. This can be done with a simple bit manipulation operation. No conditionals are required.

Parameters

x	the integer containing a IEEE floating point value

Returns

the absolute value of the parameter

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatAdd	(	iFloat_t	x,
		iFloat_t	y
	)

Add two floating point values

Parameters

x	an integer containing a IEEE floating point value
y	an integer containing a IEEE floating point value

Returns

x + y. Your code needs to account for a value of 0.0, but no other special cases (e.g. infinities)

Todo:

Implement in based on documentation contained in iFloat.h

void floatGetAll	(	iFloat_t	x,
		iFloat_t *	sign,
		iFloat_t *	exp,
		iFloat_t *	val
	)

Get the sign, exponent, and value in a single call. You will use the

Parameters

x	the integer containing a IEEE floating point value
sign	pointer to location where sign will be stored
exp	pointer to location where exponent will be stored
val	pointer to location where value will be stored C pointers to return values.

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatGetExp

(

iFloat_t

x

)

Extract the exponent of the argument

Parameters

x	the integer containing a IEEE floating point value

Returns

the biased exponent of the argument

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatGetSign

(

iFloat_t

x

)

Extract the sign of the argument

Parameters

x	the integer containing a IEEE floating point value

Returns

0 if the value is 0 or positive, 1 if it is negative

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatGetVal

(

iFloat_t

x

)

Extract the digits of the argument

Parameters

x	the integer containing a IEEE floating point value

Returns

the bits representing the value (includes the implicit 1)

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatLeftMost1

(

iFloat_t

bits

)

Extract the position of the left most 1 in the argument's bits

Parameters

bits	the integer

Returns

-1 if the value is 0, otherwise the position (0 to 31) of the left most 1 bit.

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatNegate

(

iFloat_t

x

)

Negate the argument. This can be done with a simple bit manipulation function. No conditionals are required.

Parameters

x	the integer containing a IEEE floating point value

Returns

the negation of the value

Todo:

Implement in based on documentation contained in iFloat.h

iFloat_t floatSub	(	iFloat_t	x,
		iFloat_t	y
	)

Subtract to floating point values

Parameters

x	an integer containing a IEEE floating point value
y	an integer containing a IEEE floating point value

Returns

x - y. Your code needs to account for a value of 0.0, but no other special cases (e.g. infinities)

Todo:

Implement in based on documentation contained in iFloat.h