gnupic: gpasm numbers
Subject:
Re: gpasm numbers
From:
Craig Franklin ####@####.####
Date:
25 Aug 2004 05:18:35 +0100
Message-Id: <412B23D5.4060908@users.sourceforge.net>
pico wrote:
> Additional note:
> The most misleading thing about numbers in gpasm is that the default
> radix is HEX and not DEC as in many other assembler.
I don't know which default radix is most common. I know some that are
hex and some that aren't. Good thing it is easy to change the radix if
you want. I like to do all my stuff in octal :)
> Microchip application notes requires, especially the math related, that
> the default radix is decimal.The same apply for third part code.
If they do that, they should use the radix directive in their code.
Especially when you consider that their assembler defaults to hex. Tell
which app notes and I will send them a bug report.
> The gpasm manual don't explain that the default radix is hex in the
> section related to numbers. Instead it's explained in the section
> regarding command line arguments.
At least it is in the manual. I agree that it should also be in the
numbers section of the gputils manual. I will add it.
It is also reported in the help message if you command "gpasm -h".
> As explained in the previous mail, some of
> the numeric representations explained in the gpasm manual don't work.
>
You need to be more specific. AFAIK, all representations work as
documented in the manual. I also believe that gpasm passes all of the
numeric regression tests provided by Microchip.
Some of the representations are flawed by design. Like the "21d"
example. This isn't gpasm's fault. These representations are supported
for mpasm compatibility only and are not recommended.
>
> One simple example:
>
> #define KH *1000
> #defime MH KH KH
> ; set processor speed
> #define CLK 4000000
> ; or
> #define CLK 4MH
> ; set timer0 prescaler
> #define TM0PRE 16 ; set prescaler to 16 - minimum is 4
>
>
> delay_ms:
> ; ARGS: 0-256 = W
> ; VARS: _tmp
> ; RET : W = 0
> ; NOTE: destroys the W register and set Z. C is untouched.
> ; timer0 must be started before enter this pice of code.
> ; otherwise this is a non returning call.
> ; DESC: delays 0-256 milliseconds
> ; HOOK: idle_1ms
> #if CLK / TM0PRE / D'1000' > 0xff
> #error "Prescaler in timer0 out of range"
> #endif
> movwf _tmp
> skipnz
> retlw 0
> movlw ( CLK / 4 -4 ) / D'1000' / TM0PRE
> movwf tmr0
> call idle_1ms ; idle task called every ms in a time loop
> movf tmr0
> skipz
> goto $-2
> goto delay_ms+1
>
> The result is a 3 or 4 time longer delay.
>
With a quick look, I don't any numeric problems in this example. I do
see some other problems. #defime is one. I am going to guess you are
having problems with this line:
movlw ( CLK / 4 -4 ) / D'1000' / TM0PRE
That line doesn't assemble with mpasm.
MPASM 03.80 Released TEST.ASM
8-24-2004 4:00:44 PAGE 1
LOC OBJECT CODE LINE SOURCE TEXT
VALUE
00001 processor 16f877
00002
00003 #define KH *1000
00004 #define MH KH KH
00005 ; set processor speed
00006 ;#define CLK 4000000
00007 ; or
00008 #define CLK 4MH
00009 ; set timer0 prescaler
00010 #define TM0PRE 16 ; set prescaler to 16 -
minimum is 4
00011
00012
Warning[225]: Invalid label in operand (MH)
Error[112] : Missing operator
0000 3000 00013 movlw ( CLK / 4 -4 ) / D'1000' / TM0PRE
00014
00015 end
If you put a space in the CLK macro and change the radix to decimal, it
works in mpasm and gpasm.
MPASM 03.80 Released TEST.ASM
8-24-2004 4:01:09 PAGE 1
LOC OBJECT CODE LINE SOURCE TEXT
VALUE
00001 processor 16f877
00002
00003 #define KH *1000
00004 #define MH KH KH
00005 ; set processor speed
00006 ;#define CLK 4000000
00007 ; or
00008 #define CLK 4 MH
00009 ; set timer0 prescaler
00010 #define TM0PRE 16 ; set prescaler to 16 -
minimum is 4
00011
00012
0000 303E 00013 movlw ( CLK / 4 -4 ) / D'1000' / TM0PRE
00014
00015 end
Keep in mind that the mpasm's preprocessor isn't an ANSI C preprocessor,
so some things that you are use to won't work. If you need those
features use an external preprocessor.
>
>
>
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