Lab Project – Stack and Passing Data to SubroutinesECE347_Lab3_Subs_and_Params ECE347 Lab Project –...

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Lab Project – Stack and Passing Data to SubroutinesECE347_Lab3_Subs_and_Params ECE347 Lab Project – Stack and Passing Data to Subroutines  	 1.			Start	with	a	MAIN	program,	which	initializes	an	ARRAY	of	10	8-bit	arbitrary	 numbers	and	reserves	space	for	another	10-element	array	called	EVENS.		Then	 create	subroutines	as	described	below.			MAIN	should	call	all	subroutines	in	the	 order	shown	in	this	description,	then	execute	an	infinite	loop	with	some	NOPs.	 	 2.		Subroutine	EVEN_CNT	counts	the	number	of	even	array	elements.		The	total	 element	count	for	the	source	array	(10)	is	passed	using	register	A.		The	address	of	 the	source	array	is	passed	using	register	X.		The	count	of	even	elements	is	returned	 in	register	B.		Upon	returning,	MAIN	should	save	the	B	value,	as	it	may	be	needed	 later	in	the	program.	 	 3.		Subroutine	COPY_EVEN	copies	all	the	even	array	elements	to	the	array	called	 EVENS.		The	addresses	of	the	source	and	target	arrays	are	passed	on	the	stack.		The		 number	of	elements	to	scan	(10)	is	passed	on	the	stack.	 	 4.		Subroutine	EVEN_AVE	calculates	the	average	of	EVEN	elements.		The	source	 array	address	and	number	of	even	elements	is	passed	on	the	stack.		The	average	is	 returned	in	a	"stack	hole."		If	the	number	of	even	elements	is	0,	the	subroutine	 should	exit	immediately	upon	detecting	this.		Upon	returning,	MAIN	should	store	the	 average	value	that	was	returned	from	EVEN_AVE.	 	 Test	your	code	and	document	your	results	for	the	following	cases:	 	 case	A:			seven	even	elements,	three	odd	elements	 case	B:		all	odd	elements,	no	even	elements	 	 This	is	an	official	lab	in	which	a	professional	report	is	to	be	turned	in.		Include	 in	your	single	pdf	file	an	MSPEC,	PCODE,	unit	test	plan,	and	clearly	 documented	test	results	for	all	test	cases.		The	test	results	can	be	captured	by	 using	the	SNIP	tool	on	Code	Warrior	debugger	memory	display	or	variable	 window.		Make	sure	your	documentation	is	clear	and	easy	to	read.	 	 	 	 	 				 	   CSheet_v3   1    Embedded C Programming Reference Sheet v3      Libraries, some with standard functions (like printf, getchar), are pulled into your code through include  statements:     #include   _____________________________________________________________________    All programs must have a function entitled main.  The function's return data type is declared in front of  the name; parameter type is enclosed in parens.  Code and data declarations are enclosed in {}.  Code  statements end with semi-colon:    void main(void)   {   int blob;   float scum;   printf("Hello! 
");  }    _____________________________________________________________________    All variables must have their data type declared.  Some data types are standard, but  some may be machine dependent (MD):    char   character 8 bits  int  integer 16 bits (MD)  long int (integer twice the size of an int)  float  single precision floating point  double  double precision floating point  void  means nothing is returned from /passed to a function    _____________________________________________________________________    The following KEYWORDS cannot be used for variables of functions:    auto break case char const continue default do double else enum extern float for goto if int long register  return short signed sizeof static struct switch typedef union unsigned void volatile while     The keyword extern allows for file2 to access variables that are defined in file1:    file1:  int scum;  void main(void)  {  scum = 17;  } 2      file2:  int  blob(void)  {  extern int scum;  scum = scum + 1;  return scum;  }    _____________________________________________________________________    If you want a variable to retain its value for later use, you must use the static keyword:    static int keep;    Note that this prevents BDM from putting this variable in the symbols list.    _____________________________________________________________________    You can force a variable to be stored in a CPU register (rather than memory) by using:    register int blob = 12;  _____________________________________________________________________    Constants can be declared using:    const double PI = 3.14159265;  _____________________________________________________________________    Arrays are declared using [size], and initialized using {} :    int inbuf[100];  char string1[] = {"make a character array"};  float pressure[] = {1.1,2.3,5.9,1.7};  _____________________________________________________________________    Operators:  add +, subtract -, multiply *, divide /, modulo (remainder) %,  less than , greater than or equal>=, is equal ==,  is not equal !=, logical AND &&, logical OR ||, increment ++, decrement --  _____________________________________________________________________    Bitwise operators:  logical AND &, logical OR |, exclusive OR ^, right shift >>, left shift 	;  ... go to the label    continue;   ... rarely used, causes next loop iteration to start             4    switch( variable1 )     ... process the case which equals variable1, otherwise do default  {   case 0:    x = x + 0;    break;   case 1:    x = x + 1;    break;   case 2:    x = x + 2;    break;   default:    x = x + 10;  }  _____________________________________________________________________    #define is a preprocessor command.  It tells the compiler to substitute, e.g.:    #define FALSE 0  ... causes compiler to insert a 0 when it encounters a FALSE    It can also be used to create MACRO functions, that is functions will be placed in the code wherever  their name is encountered.  This is efficient in terms of time, since there is no subroutine call, but  inefficient in terms of space usage:    #define square(x)   (x)*(x)    .... square(x) is replaced by (x)*(x) when compiled  _____________________________________________________________________    enum can be used to initialize a sequence of data, default list starts at 0 unless as shown below:  enum months (Jan = 1, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec)  _____________________________________________________________________                                 5    Functions:    Functions must first have a prototype declaration outside of main which specifies return type and  parameters passed:    double cube(float);  // function prototype. Needed if function is defined after main or in different file.    void main(void)  {   int i = 16;   double b;  float c;      c = 163.23;   b = cube(c);   // function call              printf(“The number %f cubed is %f 
”,c,b);               return;  }    double cube(float x)   // function definition ...  {   double y;   y = (x) * (x) * (x);   return y;  }  _____________________________________________________________________      Recursion is a fn that calls itself:    long factorial(int n)  {   if (n == 0)    return 1;   else    return n*factorial(n-1);  }    note that n! = n*(n-1)*(n-2)*....*2*1 = n*(n-1)!  _____________________________________________________________________     6    Pointers    Declaring/creating:    int *ar ;  // declares a pointer to an integer.  ar is of type “pointer to int”  int *temp; // declares a pointer to an integer.  temp is of type “pointer to int”  char *cp; // declares a pointer to a char (8-bit).  cp is of type “pointer to char”    Using in code:    int w,x,m,n;  char y,z;    w = 0x1234;  x = 0x5678;  y = 0x34;  z = 0x29;    ar = &w;    // ar gets ADDRESS of w  temp = ar;  // temp gets the same value as ar, which is an address    m = *temp;  // m gets contents of temp, temp points to w, thus, m = 0x1234  ar = &x;  // ar gets address of x  n = *ar;  // n gets contents of ar, ar points to x, thus, n = 0x5678;    cp = &y;  // cp gets ADDRESS of y  *cp = y;  //contents of address pointed to by cp gets set to y, or [cp] = 0x34  z = *cp;  // z gets contents pointed to by cp, z = 0x34.      More:  px = &x;   ... assigns the address of x to px... not to be confused with bitwise AND  (similar to asm language LDX   #ARRAY, get the starting address of ARRAY)    x = *px;  x is made equal to the contents of the address pointed to by px  (similar to asm language LDAA  ARRAY, get the first element of ARRAY)     More examples:    int m,n; // declare integer variables  int *pm; //declare pointer to integer    m = 10; ... assign 10 to m...  pm = &m; ... assign address of m to pm  n = *pm; ... assign contents (10) of address of m (pointed to by pm) to n...(i.e., n = 10)   7    When an array is invoked without brackets, it is evaluated as a pointer to the first location of the array  (pointer to element 0 of the array). Example:    int mongo[10];  int mongo_element;  int *pointer1;

ECE347_Lab3_Subs_and_Params ECE347 Lab Project – Stack and Passing Data to Subroutines 1. StartwithaMAINprogram,whichinitializesanARRAYof108-bitarbitrary...

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