Computer Systems: Program... -Access
3rd Edition
ISBN: 9780134071923
Author: Bryant
Publisher: PEARSON
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Expert Solution & Answer
Chapter 2, Problem 2.60HW
Explanation of Solution
Function definition for “replace_byte()” function:
The implementation for “replace_byte()” function is given below:
//Header file
#include <stdio.h>
#include <assert.h>
//Function definition for replace byte function
unsigned replace_byte(unsigned x, int i, unsigned char b)
{
//Check if value of "i" is less than "0", then
if (i < 0)
{
//Display error message
printf("error: value of i is negetive\n");
return x;
}
/* Check if value of "i" is greater than "sizeof(unsigned)-1", then */
if (i > sizeof(unsigned)-1)
{
//Display error message
printf("error: value of i is too high");
return x;
}
/* Assign the value of mask that is for byte
in general, 1 bye = 8 bits and then << implies *8 */
unsigned m = ((unsigned) 0xFF) << (i << 3);
//Defines the byte position
unsigned bytePosition = ((unsigned) b) << (i << 3);
//Return given value
return (x & ~m) | bytePosition;
}
//Main function
int main(int argc, char *argv[])
{
/* Call replace_byte function for replace byte 2 in given "x" by byte "0xAB" */
unsigned replaceByte2 = replace_byte(0x12345678, 2, 0xAB);
/* Call replace_byte function for replace byte 0 in given "x" by byte "0xAB" */
unsigned replaceByte0 = replace_byte(0x12345678, 0, 0xAB);
/* Check if the replaced byte equals to given value using "assert" function */
assert(replaceByte2 == 0x12AB5678);
assert(replaceByte0 == 0x123456AB);
return 0;
}
The given code is used to return an unsigned value in which byte “i” of argument “x” has been replaced by “b”...
Expert Solution & Answer
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Students have asked these similar questions
Suppose we number the bytes in a w-bit word from 0 (least significant)to w/8 −1 (most significant).Write code for the following C function, which will return an unsignedvalue in which byte i of argument x has been replaced by byte b:unsigned replace byte (unsigned x, int i, unsigned char b);Examples:replace byte(0x12345678, 2, 0xAB) → 0x12AB5678replace byte(0x12345678, 0, 0xAB) → 0x123456AB
Write C expressions, in terms of variable x, for the following values. Your codeshould work for any word size w > 8. For reference, we show the result of evaluatingthe expressions for x = 0x196a45c7, with w = 32.A. The least significant byte of x, with all other bits set to 0. [0x000000c7]B. All but the least significant byte of x complemented, with the least significant byteleft unchanged. [0xe695bac7 ].C. The least significant byte set to all ls’, and all other bytes of x left unchanged[0x196a45ff].
implement anyEvenBit(x) Return 1 if any even bit in x is set to 1
you are only allowed to use the following eight operators: ! ~ & ^ | + << >>
“Max ops” field gives the maximum number of operators you are allowed to use to implement each function
/* * anyEvenBit - return 1 if any even-numbered bit in word set to 1* Examples anyEvenBit(0xA) = 0, anyEvenBit(0xE) = 1* Legal ops: ! ~ & ^ | + << >>* Max ops: 12*/int anyEvenBit(int x) {return 2;}
Chapter 2 Solutions
Computer Systems: Program... -Access
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