Assembly to Get Hex Number and Display Count of Bits Set

Instructions

Objective

Write a program to get hex number and display count of bits set in assembly language.

Requirements and Specifications

Description:

Write an x86 assembler assignment program that does the following:

Gets a 32-bit number (up to 8 hex digits) from the console
Determines the frequencies for each “power of two” that contributes to every bit set in that number.

The powers of two to 32 bits positions are: 1, 2, 4, 8, 16 and 32

Output the frequency counts to the console

This program must include at least one procedure beyond MAIN.

Example:

For a hex input of 0F (0x1111b), only the low 4 bits of a 32 bit word (bits 1, 2, 3 and 4) are set. To set this sequence of bits, you need to use 1 twice, 2 twice and 4 once. The below shows the particular power of two sums for each bit position set.

1 = 1,
2 = 2,
3 = 1 + 2,
4 = 4

Screenshots of output

Assembly language program to get hex number and display count of bits set 1

Assembly language program to get hex number and display count of bits set 2

Source Code

TITLE CPSC 232 - Program #4
INCLUDE IRVINE32.INC
.DATA
TITLEMSG BYTE "CPSC 232 - Program #4", 0DH, 0AH, 0DH, 0AH, 0
MESSAGE BYTE "Input a 32-bit word (8 hex digits) >> ", 0
OUTPUT1 BYTE 0DH, 0AH, "1's frequency = ", 0
OUTPUT2 BYTE 0DH, 0AH, "2's frequency = ", 0
OUTPUT4 BYTE 0DH, 0AH, "4's frequency = ", 0
OUTPUT8 BYTE 0DH, 0AH, "8's frequency = ", 0
OUTPUT16 BYTE 0DH, 0AH, "16's frequency = ", 0
OUTPUT32 BYTE 0DH, 0AH, "32's frequency = ", 0
FREQ1 DWORD 0
FREQ2 DWORD 0
FREQ4 DWORD 0
FREQ8 DWORD 0
FREQ16 DWORD 0
FREQ32 DWORD 0
.CODE
FREQUENCIES PROC
  mov EBX, 1 ; Bit to test
LOOP1: cmp EBX, 32 ; If the bit is above the 32
  jg ENDL1 ; end the loop
  shr EAX, 1 ; shift input
  jnc SKIP1 ; If not set, skip
  mov EDX, EBX ; Copy bit position to EDX
  shr EDX, 1 ; test first bit
  adc DWORD PTR [FREQ1], 0 ; increment frequency 1 if the bit was set
  shr EDX, 1 ; test second bit
  adc DWORD PTR [FREQ2], 0 ; increment frequency 2 if the bit was set
  shr EDX, 1 ; test first bit
  adc DWORD PTR [FREQ4], 0 ; increment frequency 4 if the bit was set
  shr EDX, 1 ; test first bit
  adc DWORD PTR [FREQ8], 0 ; increment frequency 8 if the bit was set
  shr EDX, 1 ; test first bit
  adc DWORD PTR [FREQ16], 0 ; increment frequency 16 if the bit was set
  shr EDX, 1 ; test first bit
  adc DWORD PTR [FREQ32], 0 ; increment frequency 32 if the bit was set
SKIP1: inc EBX ; Increment bit position
  jmp LOOP1 ; Repeat the loop
ENDL1: ret ; Return to main
FREQUENCIES ENDP
MAIN PROC
  lea EDX, TITLEMSG ; Load addess of title in EDX
  call WriteString ; Write string on console
  lea EDX, MESSAGE ; Load addess of message in EDX
  call WriteString ; Write string on console
  call ReadHex ; Read number in hexadecimal
  call FREQUENCIES ; call frequencies subroutine with EAX = read number
  lea EDX, OUTPUT1 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ1] ; load frequency value
  call WriteDec ; Write value on console
  lea EDX, OUTPUT2 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ2] ; load frequency value
  call WriteDec ; Write value on console
  lea EDX, OUTPUT4 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ4] ; load frequency value
  call WriteDec ; Write value on console
  lea EDX, OUTPUT8 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ8] ; load frequency value
  call WriteDec ; Write value on console
  lea EDX, OUTPUT16 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ16] ; load frequency value
  call WriteDec ; Write value on console
  lea EDX, OUTPUT32 ; Load addess of output message in EDX
  call WriteString ; Write output string on console
  mov EAX, [FREQ32] ; load frequency value
  call WriteDec ; Write value on console
  call CRLF ; Print CR/LF
  Exit ; Terminate program
MAIN ENDP
END MAIN

Assembly Language Program to Get Hex Number and Display Count of Bits Set Assignment Solution.

Instructions

Requirements and Specifications