Question

ARM assembly using breadboard

Ladder Game - This game involves a setup of LEDs in a row and a button. The goal is to get from the bottom led all the way to the top without them resetting. The LEDs will flash and you can only move up one led at a time, when the led is lit up, or else you get reset to the bottom.

code in C please convert to ARM assembly

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

#include <wiringPi.h>

#ifndef TRUE
#  define       TRUE    (1==1)
#  define       FALSE   (1==2)
#endif

#undef  DEBUG

// The input button

#define BUTTON          8


// Map the LEDs to the hardware pins
//      using wiringPi pin numbers here

const int ledMap [12] =
{
  13, 12, 11, 10, 7, 6, 5, 4, 3, 2, 1, 0
} ;


// Some constants for our circuit simulation

const double vBatt      =      9.0 ;    // Volts (ie. a PP3)
const double capacitor  =      0.001 ;  // 1000uF
const double rCharge    =   2200.0 ;    // ohms
const double rDischarge =  68000.0 ;    // ohms
const double timeInc    =      0.01 ;   // Seconds

double vCharge, vCap, vCapLast ;



/*
 * setup:
 *      Program the GPIO correctly and initialise the lamps
 ***********************************************************************
 */

void setup (void)
{
  int i ;

  if (geteuid () != 0)
  {
    fprintf (stderr, "ladder: Need to be root to run (sudo?)\n") ;
    exit (0) ;
  }

  if (wiringPiSetup () == -1)
    exit (1) ;

  for (i = 0 ; i < 12 ; ++i)
  {
    digitalWrite (ledMap [i], 0) ;
    pinMode (ledMap [i], OUTPUT) ;
  }

  pinMode (BUTTON, INPUT) ;

// Calculate the actual charging voltage - standard calculation of
//      vCharge = r2 / (r1 + r2) * vBatt
//
//
//   -----+--- vBatt
//        |
//        R1
//        |
//        +---+---- vCharge
//        |   |
//        R2  C
//        |   |
//   -----+---+-----

  vCharge = rDischarge / (rCharge + rDischarge) * vBatt ;

// Start with no charge

  vCap    = vCapLast = 0.0 ;
}


/*
 * introLeds
 *      Put a little pattern on the LEDs to start with
 *********************************************************************************
 */

void introLeds (void)
{
  int i, j ;


  printf ("Pi Ladder\n") ;
  printf ("=========\n\n") ;
  printf ("       vBatt: %6.2f volts\n", vBatt) ;
  printf ("     rCharge: %6.0f ohms\n", rCharge) ;
  printf ("  rDischarge: %6.0f ohms\n", rDischarge) ;
  printf ("     vCharge: %6.2f volts\n", vCharge) ;
  printf ("   capacitor: %6.0f uF\n", capacitor * 1000.0) ;

// Flash 3 times:

  for (j = 0 ; j < 3 ; ++j)
  {
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 1) ;
    delay (500) ;
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }

// All On

  for (i = 0 ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 1) ;
  delay (500) ;

// Countdown...

  for (i = 11 ; i >= 0 ; --i)
  {
    digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }
  delay (500) ;
}


/*
 * winningLeds
 *      Put a little pattern on the LEDs to start with
 *********************************************************************************
 */

void winningLeds (void)
{
  int i, j ;

// Flash 3 times:

  for (j = 0 ; j < 3 ; ++j)
  {
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 1) ;
    delay (500) ;
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }

// All On

  for (i = 0 ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 1) ;
  delay (500) ;

// Countup...

  for (i = 0 ; i < 12 ; ++i)
  {
    digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }
  delay (500) ;
}


/*
 * chargeCapacitor: dischargeCapacitor:
 *      Add or remove charge to the capacitor.
 *      Standard capacitor formulae.
 *********************************************************************************
 */

void chargeCapacitor (void)
{
  vCap = (vCapLast - vCharge) *
        exp (- timeInc / (rCharge * capacitor)) + vCharge ;

#ifdef  DEBUG
  printf ("+vCap: %7.4f\n", vCap) ;
#endif

  vCapLast = vCap ;
}

void dischargeCapacitor (void)
{
  vCap = vCapLast *
        exp (- timeInc / (rDischarge * capacitor)) ;

#ifdef  DEBUG
  printf ("-vCap: %7.4f\n", vCap) ;
#endif

  vCapLast = vCap ;
}


/*
 * ledBargraph:
 *      Output the supplied number as a bargraph on the LEDs
 *********************************************************************************
 */

void ledBargraph (double value, int topLedOn)
{
  int topLed = (int)floor (value / vCharge * 12.0) + 1 ;
  int i ;

  if (topLed > 12)
    topLed = 12 ;

  if (!topLedOn)
    --topLed ;

  for (i = 0 ; i < topLed ; ++i)
    digitalWrite (ledMap [i], 1) ;

  for (i = topLed ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 0) ;
}


/*
 * ledOnAction:
 *      Make sure the leading LED is on and check the button
 *********************************************************************************
 */

void ledOnAction (void)
{
  if (digitalRead (BUTTON) == LOW)
  {
    chargeCapacitor () ;
    ledBargraph (vCap, TRUE) ;
  }
}


/*
 * ledOffAction:
 *      Make sure the leading LED is off and check the button
 *********************************************************************************
 */

void ledOffAction (void)
{
  dischargeCapacitor () ;

// Are we still pushing the button?

  if (digitalRead (BUTTON) == LOW)
  {
    vCap = vCapLast = 0.0 ;
    ledBargraph (vCap, FALSE) ;

// Wait until we release the button

    while (digitalRead (BUTTON) == LOW)
      delay (10) ;
  }
}


/*
 ***********************************************************************
 * The main program
 ***********************************************************************
 */

int main (void)
{
  unsigned int then, ledOnTime, ledOffTime ;
  unsigned int ourDelay = (int)(1000.0 * timeInc) ;
  
  setup     () ;
  introLeds () ;

// Setup the LED times - TODO reduce the ON time as the game progresses

  ledOnTime  = 1000 ;
  ledOffTime = 1000 ;

// This is our Gate/Squarewave loop

  for (;;)
  {

// LED ON:

    (void)ledBargraph (vCap, TRUE) ;
    then = millis () + ledOnTime ;
    while (millis () < then)
    {
      ledOnAction () ;
      delay       (ourDelay) ;
    }

// Have we won yet?
//      We need vCap to be in the top 12th of the vCharge

    if (vCap > (11.0 / 12.0 * vCharge))      // Woo hoo!
    {
      winningLeds () ;
      while (digitalRead (BUTTON) == HIGH)
        delay (10) ;
      while (digitalRead (BUTTON) == LOW)
        delay (10) ;
      vCap = vCapLast = 0.0 ;
    }

// LED OFF:

    (void)ledBargraph (vCap, FALSE) ;
    then = millis () + ledOffTime ;
    while (millis () < then)
    {
      ledOffAction () ;
      delay        (ourDelay) ;
    }

  }

  return 0 ;
}

ARM assembly using breadboard

Ladder Game - This game involves a setup of LEDs in a row and a button. The goal is to get from the bottom led all the way to the top without them resetting. The LEDs will flash and you can only move up one led at a time, when the led is lit up, or else you get reset to the bottom.

code in C please convert to ARM assembly

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

#include <wiringPi.h>

#ifndef TRUE
#  define       TRUE    (1==1)
#  define       FALSE   (1==2)
#endif

#undef  DEBUG

// The input button

#define BUTTON          8


// Map the LEDs to the hardware pins
//      using wiringPi pin numbers here

const int ledMap [12] =
{
  13, 12, 11, 10, 7, 6, 5, 4, 3, 2, 1, 0
} ;


// Some constants for our circuit simulation

const double vBatt      =      9.0 ;    // Volts (ie. a PP3)
const double capacitor  =      0.001 ;  // 1000uF
const double rCharge    =   2200.0 ;    // ohms
const double rDischarge =  68000.0 ;    // ohms
const double timeInc    =      0.01 ;   // Seconds

double vCharge, vCap, vCapLast ;



/*
 * setup:
 *      Program the GPIO correctly and initialise the lamps
 ***********************************************************************
 */

void setup (void)
{
  int i ;

  if (geteuid () != 0)
  {
    fprintf (stderr, "ladder: Need to be root to run (sudo?)\n") ;
    exit (0) ;
  }

  if (wiringPiSetup () == -1)
    exit (1) ;

  for (i = 0 ; i < 12 ; ++i)
  {
    digitalWrite (ledMap [i], 0) ;
    pinMode (ledMap [i], OUTPUT) ;
  }

  pinMode (BUTTON, INPUT) ;

// Calculate the actual charging voltage - standard calculation of
//      vCharge = r2 / (r1 + r2) * vBatt
//
//
//   -----+--- vBatt
//        |
//        R1
//        |
//        +---+---- vCharge
//        |   |
//        R2  C
//        |   |
//   -----+---+-----

  vCharge = rDischarge / (rCharge + rDischarge) * vBatt ;

// Start with no charge

  vCap    = vCapLast = 0.0 ;
}


/*
 * introLeds
 *      Put a little pattern on the LEDs to start with
 *********************************************************************************
 */

void introLeds (void)
{
  int i, j ;


  printf ("Pi Ladder\n") ;
  printf ("=========\n\n") ;
  printf ("       vBatt: %6.2f volts\n", vBatt) ;
  printf ("     rCharge: %6.0f ohms\n", rCharge) ;
  printf ("  rDischarge: %6.0f ohms\n", rDischarge) ;
  printf ("     vCharge: %6.2f volts\n", vCharge) ;
  printf ("   capacitor: %6.0f uF\n", capacitor * 1000.0) ;

// Flash 3 times:

  for (j = 0 ; j < 3 ; ++j)
  {
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 1) ;
    delay (500) ;
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }

// All On

  for (i = 0 ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 1) ;
  delay (500) ;

// Countdown...

  for (i = 11 ; i >= 0 ; --i)
  {
    digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }
  delay (500) ;
}


/*
 * winningLeds
 *      Put a little pattern on the LEDs to start with
 *********************************************************************************
 */

void winningLeds (void)
{
  int i, j ;

// Flash 3 times:

  for (j = 0 ; j < 3 ; ++j)
  {
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 1) ;
    delay (500) ;
    for (i = 0 ; i < 12 ; ++i)
      digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }

// All On

  for (i = 0 ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 1) ;
  delay (500) ;

// Countup...

  for (i = 0 ; i < 12 ; ++i)
  {
    digitalWrite (ledMap [i], 0) ;
    delay (100) ;
  }
  delay (500) ;
}


/*
 * chargeCapacitor: dischargeCapacitor:
 *      Add or remove charge to the capacitor.
 *      Standard capacitor formulae.
 *********************************************************************************
 */

void chargeCapacitor (void)
{
  vCap = (vCapLast - vCharge) *
        exp (- timeInc / (rCharge * capacitor)) + vCharge ;

#ifdef  DEBUG
  printf ("+vCap: %7.4f\n", vCap) ;
#endif

  vCapLast = vCap ;
}

void dischargeCapacitor (void)
{
  vCap = vCapLast *
        exp (- timeInc / (rDischarge * capacitor)) ;

#ifdef  DEBUG
  printf ("-vCap: %7.4f\n", vCap) ;
#endif

  vCapLast = vCap ;
}


/*
 * ledBargraph:
 *      Output the supplied number as a bargraph on the LEDs
 *********************************************************************************
 */

void ledBargraph (double value, int topLedOn)
{
  int topLed = (int)floor (value / vCharge * 12.0) + 1 ;
  int i ;

  if (topLed > 12)
    topLed = 12 ;

  if (!topLedOn)
    --topLed ;

  for (i = 0 ; i < topLed ; ++i)
    digitalWrite (ledMap [i], 1) ;

  for (i = topLed ; i < 12 ; ++i)
    digitalWrite (ledMap [i], 0) ;
}


/*
 * ledOnAction:
 *      Make sure the leading LED is on and check the button
 *********************************************************************************
 */

void ledOnAction (void)
{
  if (digitalRead (BUTTON) == LOW)
  {
    chargeCapacitor () ;
    ledBargraph (vCap, TRUE) ;
  }
}


/*
 * ledOffAction:
 *      Make sure the leading LED is off and check the button
 *********************************************************************************
 */

void ledOffAction (void)
{
  dischargeCapacitor () ;

// Are we still pushing the button?

  if (digitalRead (BUTTON) == LOW)
  {
    vCap = vCapLast = 0.0 ;
    ledBargraph (vCap, FALSE) ;

// Wait until we release the button

    while (digitalRead (BUTTON) == LOW)
      delay (10) ;
  }
}


/*
 ***********************************************************************
 * The main program
 ***********************************************************************
 */

int main (void)
{
  unsigned int then, ledOnTime, ledOffTime ;
  unsigned int ourDelay = (int)(1000.0 * timeInc) ;
  
  setup     () ;
  introLeds () ;

// Setup the LED times - TODO reduce the ON time as the game progresses

  ledOnTime  = 1000 ;
  ledOffTime = 1000 ;

// This is our Gate/Squarewave loop

  for (;;)
  {

// LED ON:

    (void)ledBargraph (vCap, TRUE) ;
    then = millis () + ledOnTime ;
    while (millis () < then)
    {
      ledOnAction () ;
      delay       (ourDelay) ;
    }

// Have we won yet?
//      We need vCap to be in the top 12th of the vCharge

    if (vCap > (11.0 / 12.0 * vCharge))      // Woo hoo!
    {
      winningLeds () ;
      while (digitalRead (BUTTON) == HIGH)
        delay (10) ;
      while (digitalRead (BUTTON) == LOW)
        delay (10) ;
      vCap = vCapLast = 0.0 ;
    }

// LED OFF:

    (void)ledBargraph (vCap, FALSE) ;
    then = millis () + ledOffTime ;
    while (millis () < then)
    {
      ledOffAction () ;
      delay        (ourDelay) ;
    }

  }

  return 0 ;
}

Answer 1

Ans:

The code given above which is a ladder program for LED pattern in C can be easily converted into assembly code by using the following two techniques if all of the required compiled libraries and headers are present in the system :-

1st Technique - only using the internal gcc compiler features to generate the assembly code

Step 1 : compile the C code using the following command:

gcc -S Sample.c -o Sample.s

(Where using the -o argument changes the name of the file to intermediate assembly code having ".s" extension i.e let the compiler do all the heavy lifting)

This will cause gcc to run the compiler, generating an assembly file Sample.s , and go no further. (Normally it would then invoke the assembler to generate an object- code file.)

OUTPUT after running the above command for the file:

The same result can also be achieved by using the features of VS Code by debugging the code using the 'disassembly' window. The Disassembly window shows assembly code corresponding to the instructions created by the compiler.

Step 1: To enable the Disassembly window, under Tools > Options (or Tools > Options) > Debugging, select Enable address-level debugging.

and

Step 2: To open the Disassembly window during debugging, select Windows > Disassembly or press Alt+8.

The above two techniques can be used for generating the assembly from a C source code if all the required headers are present with the programmer. ( Since the header file <wiringPi> was not provided with the C code the code cannot be generated without it but if the header is present it can easily be done using the above mentioned methods )

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