Test Program #3 Source Code

/*
 * neil_3.c
 * code generation demo
 */
#define ushrt unsigned short
 
ushrt one,two,three,three_a;
 
/*
 *    use a function to do some top of stack math
 */
ushrt add_them(ushrt a, ushrt b)
{   return(a+b);
}
 
void main(void)
{   one     = 1;     /* init globals (ascending) */
    two     = 2;
    three   = 3;
    three_a = 3;
    three_a = add_them(one,two); 
}

Code Listing From the COSMIC Software Compiler

 Notes:
 1. program code size: 43-0+1=44 bytes
 2. notice the use of incb (1 byte) instead of ldd (3 bytes) on lines 23 + 26
 3. function code: size: 10-0+1=11 bytes
   1                     ; C Compiler for MC68HC11 [COSMIC Software]
   2                     ; Version V4.0g - 16 Apr 1997
   4                     ; 12 ushrt add_them(ushrt a, ushrt b)
   4                     ; 13 {   return(a+b);
   5  0000               _add_them:
   6  0000 3c            	pshx	
   7                     	pshd	
   8  0003 30            	tsx	
   9       00000000      OFST:	set	0
  11  0004 ec00          	ldd	OFST+0,x
  12  0006 e306          	addd	OFST+6,x
  14  0008 38            	pulx	
  15  0009 38            	pulx	
  16  000a 39            	rts	
  17                     ; 16 void main(void)
  17                     ; 17 {   one     = 1; /* init globals (ascending) */
  18  000b               _main:
  20  000b cc0001        	ldd	#1
  21  000e fd0006        	std	_one
  22                     ; 18     two     = 2;
  23  0011 5c            	incb	
  24  0012 fd0004        	std	_two
  25                     ; 19     three   = 3;
  26  0015 5c            	incb	
  27  0016 fd0002        	std	_three
  28                     ; 20     three_a = 3;
  29  0019 fd0000        	std	_three_a
  30                     ; 21     three_a = add_them(one,two); 
  31  001c fc0004        	ldd	_two
  32                     	pshd	
  33  0021 fc0006        	ldd	_one
  34  0024 8dda          	jsr	_add_them
  35  0026 31            	ins	
  36  0027 31            	ins	
  37  0028 fd0000        	std	_three_a
  38                     ; 22 }
  39  002b 39            	rts	
  40                     	xdef	_main
  41                     	xdef	_add_them
  42                     	switch	.bss
  43  0000               _three_a:
  44  0000 0000          	ds.b	2
  45                     	xdef	_three_a
  46  0002               _three:
  47  0002 0000          	ds.b	2
  48                     	xdef	_three
  49  0004               _two:
  50  0004 0000          	ds.b	2
  51                     	xdef	_two
  52  0006               _one:
  53  0006 0000          	ds.b	2
  54                     	xdef	_one
  55                     	end

Code Listing From a Competing Company's Compiler

 Notes:
 1. program code size: 49-0+1=50 bytes
 2. five different products produced almost the same output
 3. the compiler's optimizer switch was enabled
 4. function code size: 10-0+1=11 bytes
			    1	$	lbra,hc11
			    2		defseg	c_text,class=CODE
			    3		defseg	c_const,class=CODE
			    4		defseg	c_strings,class=CODE
			    5		defseg	c_data,class=CODE
			    6		defseg	c_bss,class=DATA
			    7		defseg	c_rdata,class=CODE
			    8		defseg	c_rbss,class=PAGE0
			    9		defseg	c_temp,class=PAGE0,overlaid
			   10		defseg	c_vectors,start=$FFC0,overlaid
			   11		seg c_temp
0000& (0004)		   12	ctemp	rmb	4
			   13		seg c_rbss
			   14		seg	c_text
			   15		global	_add_them
			   16		signat	_add_them,8250
0000& 30 		   17		tsx
0001& ED 00 		   18		std	0,x
			   19	_add_them
0003& 3C 		   20		pshx
0004& 30 		   21		tsx
0005& EC 00 		   22		ldd	0,x
0007& E3 04 		   23		addd	4,x
0009& 38 		   24		pulx
000A& 39 		   25		rts
			   26		global	_main
			   27		signat	_main,24
			   28		global	_one
			   29		global	_two
			   30		global	_three
			   31		global	_three_a
			   32	_main
000B& CC 0001 		   33		ldd	#1
000E& FD 0000& 		   34		std	_one
			   35	;neil_3.c: 18: two = 2;
0011& CC 0002 		   36		ldd	#2
0014& FD 0006& 		   37		std	_two
			   38	;neil_3.c: 19: three = 3;
0017& CC 0003 		   39		ldd	#3
001A& FD 0002& 		   40		std	_three
			   41	;neil_3.c: 20: three_a = 3;
001D& CC 0003 		   42		ldd	#3
0020& FD 0004& 		   43		std	_three_a
			   44	;neil_3.c: 21: three_a = add_them(one,two);
0023& FE 0006& 		   45		ldx	_two
0026& 3C 		   46		pshx
0027& FC 0000& 		   47		ldd	_one
002A& BD 0003& 		   48		jsr	_add_them
002D& 38 		   49		pulx
002E& FD 0004& 		   50		std	_three_a
			   51	;neil_3.c: 22: }
0031& 39 		   52		rts
			   53		seg	c_bss
			   54	_one
0000& (0002)		   55		rmb	2
			   56	_three
0002& (0002)		   57		rmb	2
			   58	_three_a
0004& (0002)		   59		rmb	2
			   60	_two
0006& (0002)		   61		rmb	2
			   62	
			   63		end
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Neil Rieck
Kitchener - Waterloo - Cambridge, Ontario, Canada.