Well, I trimmed the code somewhat to remove a lot of my
application-specific parts.  Here's most of it, at least enough to see
what's going on:

....................     clock -= 8192;
*
005B:  MOVLW  00
005C:  SUBWF  34,F
005D:  MOVLW  20
005E:  BTFSS  03.0
005F:  MOVLW  21
0060:  SUBWF  35,F
0061:  MOVLW  00
0062:  BTFSS  03.0
0063:  MOVLW  01
0064:  SUBWF  36,F
0065:  MOVLW  00
0066:  BTFSS  03.0
0067:  MOVLW  01
0068:  SUBWF  37,F
....................         restart_wdt();
0069:  CLRWDT
....................     if(clock < 8192) {
006A:  MOVF   37,F
006B:  BTFSS  03.2
006C:  GOTO   087
006D:  MOVF   36,F
006E:  BTFSS  03.2
006F:  GOTO   087
0070:  MOVF   35,W
0071:  SUBLW  1F
0072:  BTFSS  03.0
0073:  GOTO   087
....................         elapsed.seconds++;
0074:  INCF   30,F
....................         clock += 1000000;
0075:  MOVLW  40
0076:  ADDWF  34,F
0077:  MOVLW  42
0078:  BTFSC  03.0
0079:  MOVLW  43
007A:  ADDWF  35,F
007B:  MOVLW  0F
007C:  BTFSC  03.0
007D:  MOVLW  10
007E:  ADDWF  36,F
007F:  MOVLW  00
0080:  BTFSC  03.0
0081:  MOVLW  01
0082:  ADDWF  37,F
....................         if(dtimer) dtimer--;
0083:  MOVF   39,F
0084:  BTFSC  03.2
0085:  GOTO   087
0086:  DECF   39,F
....................     }
....................
....................     if(elapsed.seconds == 60) {
0087:  MOVF   30,W
0088:  SUBLW  3C
0089:  BTFSS  03.2
008A:  GOTO   091
....................         elapsed.minutes++;
008B:  INCF   2F,F
....................         elapsed.seconds = 0;
008C:  CLRF   30
....................         if(tripdelay) tripdelay--;
008D:  MOVF   3A,F
008E:  BTFSC  03.2
008F:  GOTO   091
0090:  DECF   3A,F
....................     }
....................     if(elapsed.minutes == 60) {
0091:  MOVF   2F,W
0092:  SUBLW  3C
0093:  BTFSS  03.2
0094:  GOTO   097
....................         elapsed.hours++;
0095:  INCF   2E,F
....................         elapsed.minutes = 0;
0096:  CLRF   2F
....................     }
....................


What I really like about C is the fact that I can build some relatively
complicated functions and have the compiler figure out the best way to do
the low level work while I concentrate on the overall program/product.
I'm sure I pay a small penalty in code space, but so far I have not had a
single project outgrow the chip I started out with -- in fact, most of the
time I find out I can use a smaller chip than I originally thought.  Like
this - I wanted to split the hours into two digits for display, and look
up those two digits in a table containing the 7-segment patterns for the
digits 0-9 and 'd':

....................         digit1 = sseg[set.hours % 10];
009F:  MOVF   31,W
00A0:  MOVWF  42
00A1:  MOVLW  0A
00A2:  MOVWF  43
00A3:  CALL   046
00A4:  MOVF   20,W
00A5:  CALL   037
00A6:  MOVWF  21
00A7:  MOVWF  40
....................         digit2 = sseg[set.hours/10];
00A8:  MOVF   31,W
00A9:  MOVWF  42
00AA:  MOVLW  0A
00AB:  MOVWF  43
00AC:  CALL   046
00AD:  MOVF   21,W
00AE:  CALL   037
00AF:  MOVWF  21
00B0:  MOVWF  41

Would have taken me a week to figure that out, and it's what I call
"delicate" - if I change something somewhere else in the program, this is
easily broken by geting pushed past a bank boundary or some such nonsense.
With the compiler, I **never** have to care about where something is
located, the compiler does the bank switching and RAM allocation with
complete transparency.  I love it.  I used to prefer three hours of
soldering to avoid a few dozen lines of assembly code...  now I can code
for an hour or two and eliminate most of the parts in a design, most of
the time.  Maybe I'm just not properly "wired" to love assembly...  with
the 8048 and 8051 it was never a big problem, but with the PIC a simple
test and branch is just such a pain in the ass.

Dale
--
"Curiosity is the very basis of education and if you tell me that
curiosity killed the cat, I say only the cat died nobly."
          - Arnold Edinborough


On Fri, 15 Mar 2002, Claudio Tagliola wrote:

> Hi Dale,
>
> I'm new to the CCS compiler, can you show the resulting code of this
> program? I'm curious on how the compiler does it's job. I've ordered
> CCS, but haven't received it yet, so can't do it myself :)

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