Problem 2. Consider an 8-light lighting system that is controlled by an array of

Question

Problem 2. Consider an 8-light lighting system that is controlled by an array of 8-bit registers. The first element of the array controls light #1, the second element of the array controls light #2, and so on. We call these registers Light Status Register or LSR. For each LSR, the bits control the light based on the below specification Bit 7-6: control the light intensity: 00 off, 01 low, 10 medium, 11 high. Bit 5-4: control the color: blue 00, green 01, red 10, yellow 11. Bit 3 controls whether the light flickers: 0 no flicker, 1 flicker Bit 2-0 are unused .

Explanation / Answer

I am pasting the code here, please copy paste it in lightsystem.c file and then compile and run with following commands.

Compile Command : gcc -o light lightsystem.c

Run Command : ./light

The CODE:  

#include<stdio.h>
#include<stdlib.h>

/* Answer C in next 3 lines */
#define INTENSITY_MASK(I) ((I>>6) & 3)
#define COLOR_MASK(C) ((C>>4) & 3)
#define FLICKER_MASK(F) ((F>>3) & 1)

/* Answer D in next 3 lines */
typedef enum {BLUE=0, GREEN=1, RED=2, YELLOW=3}COLOR;
typedef enum {OFF=0, LOW_INTENSITY=1, MED_INTENSITY=2, HIGH_INTENSITY=3}INTENSITY;
typedef enum {NO_FLICKER=0, FLICKER=1}FLICKERING;

/* Answer E */
COLOR extractColor(unsigned int LSR)
{
   int col;
   col = COLOR_MASK(LSR);
   switch(col)
   {
       case 0:
           printf("BLUE ");
           return BLUE;
       case 1:
           printf("GREEN ");
           return GREEN;
       case 2:
           printf("RED ");
           return RED;
       case 3:
           printf("YELLOW ");
           return YELLOW;
      
   }
}

/* Answer B*/
void extractMeaning(unsigned int LSR)
{
   int col;
   col = COLOR_MASK(LSR);
   switch(col)
   {
       case 0:
           printf("BLUE ");
           break;
       case 1:
           printf("GREEN ");
           break;
       case 2:
           printf("RED ");
           break;
       case 3:
           printf("YELLOW ");
           break;
      
   }
  
   col = INTENSITY_MASK(LSR);
   switch(col)
   {
       case 0:
           printf("OFF ");
           break;
       case 1:
           printf("LOW INTENSITY");
           break;
       case 2:
           printf("MED_INTENSITY ");
           break;
       case 3:
           printf("HIGH INTENSITY ");
           break;
      
   }
  
   col = FLICKER_MASK(LSR);
   switch(col)
   {
       case 0:
           printf("NO FLICKER ");
           break;
       case 1:
           printf("With FLICKER ");
           break;
      
   }
  
}
/* Answer F*/
unsigned int makeLSR(INTENSITY newIntensity, COLOR newColor, FLICKERING newFlickering)
{
   int LSR;
   LSR = (newIntensity<<6) | (newColor<<4) | (newFlickering<<3);
   return LSR;
}

void main()
{
   COLOR col = extractColor(0xff);
   int LSR_ARRAY[8] = {0xff,0xab,0x90,0xad,0x88,0x89,0x77,0x99};
   int i, temp;
   int lsr = makeLSR(MED_INTENSITY, BLUE, NO_FLICKER);
   printf("Make LSR : %X ",lsr);
  
   //Answer A
   lsr = makeLSR(HIGH_INTENSITY, GREEN, NO_FLICKER);
   printf("Make LSR in HEXADECIMAL: %X ",lsr);
   printf("Make LSR in Binary : ");
   temp = lsr;
   for(i=7;i>=0;i--)
   {
      
       printf("%d", (temp>>i & 1));
   }
   printf(" ");
  
   //Answer B
   extractMeaning(0xAD);
  
   // Answer G starts from here and till the end of main  
   printf("Before Change in LSR ARRAY : ");              
   for(i=0;i<8;i++)
   {
       printf("LSR_ARRAY[%d] = %X ",i,LSR_ARRAY[i]);
   }
   for(i=0;i<8;i++)
   {
       temp = INTENSITY_MASK(LSR_ARRAY[i]);
       if(temp != HIGH_INTENSITY)
       {
           temp = temp+1;
          
           lsr = (temp<<6) | (COLOR_MASK(LSR_ARRAY[i])<<4) | (FLICKER_MASK(LSR_ARRAY[i])<<3);
           LSR_ARRAY[i] = lsr;
       }
   }
   printf("After Change in LSR ARRAY : ");
   for(i=0;i<8;i++)
   {
       printf("LSR_ARRAY[%d] = %X ",i,LSR_ARRAY[i]);
   }

}

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.