COMPUTER SYSTEMS&MOD MSGT/ET SA AC PKG
COMPUTER SYSTEMS&MOD MSGT/ET SA AC PKG
3rd Edition
ISBN: 9780134671123
Author: Bryant
Publisher: PEARSON
Expert Solution & Answer
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Chapter 4.1, Problem 4.4PP

Explanation of Solution

Given C code:

long rsum(long *start, long count)

{

if(count <= 0)

return 0;

return *start + rsum(start+1, count-1);

}

Data movement instructions:

  • The different instructions are been grouped as “instruction classes”.
  • The instructions in a class performs same operation but with different sizes of operand.
  • The “Mov” class denotes data movement instructions that copy data from a source location to a destination.
  • The class has 4 instructions that includes:
    • movb:
      • It copies data from a source location to a destination.
      • It denotes an instruction that operates on 1 byte data size.
    • movw: 
      • It copies data from a source location to a destination.
      • It denotes an instruction that operates on 2 bytes data size.
    • movl:
      • It copies data from a source location to a destination.
      • It denotes an instruction that operates on 4 bytes data size.
    • movq:
      • It copies data from a source location to a destination.
      • It denotes an instruction that operates on 8 bytes data size.

Corresponding x86-64 code:

long rsum(long *start, long count)

start in %rdi, count in %rsi

rsum:

movl $0, %eax     

testq %rsi, %rsi

jle .L9

pushq %rbx

movq (%rdi),%rbx

subq $1, %rsi

addq $8, %rdi

call rsum

addq %rbx, %rax

popq %rbx

.L9:

rep; ret

Explanation:

  • The instruction “movl $0, %eax” initializes value in register “%eax” to 0.
  • The instruction “testq %rsi, %rsi” checks for count to be zero.
  • The instruction “jle .L9” jumps to label “.L9” if first value is less than or equal to second.
  • The instruction “pushq %rbx” saves callee-saved register.
  • The instruction “movq (%rdi),%rbx” moves value at location of register “%rdi” to register “%rbx”.
  • The instruction “subq $1, %rsi” decrements value of “count” stored in register “%rsi”...

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using r language
Programming Problems 9.28 Assume that a system has a 32-bit virtual address with a 4-KB page size. Write a C program that is passed a virtual address (in decimal) on the command line and have it output the page number and offset for the given address. As an example, your program would run as follows: ./addresses 19986 Your program would output: The address 19986 contains: page number = 4 offset = 3602 Writing this program will require using the appropriate data type to store 32 bits. We encourage you to use unsigned data types as well. Programming Projects Contiguous Memory Allocation In Section 9.2, we presented different algorithms for contiguous memory allo- cation. This project will involve managing a contiguous region of memory of size MAX where addresses may range from 0 ... MAX - 1. Your program must respond to four different requests: 1. Request for a contiguous block of memory 2. Release of a contiguous block of memory 3. Compact unused holes of memory into one single block 4.…
using r language

Chapter 4 Solutions

COMPUTER SYSTEMS&MOD MSGT/ET SA AC PKG

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