- Original Message -
From: "Roberto Padovani"
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 5:31 PM
Subject: Re: [Mspgcc-users] Code generation question
> I'll be brief because it's beer time here.
>
It's important t
On 2006-07-03, Lichen Wang wrote:
> P1IN is a hardware read-only 8-bit Special Function Register
> (SFR). Every time you read it, it gives a potentially
> different result. In addition, it may result in some side
> effect in the hardware.
>
> Suppose I want to read P1IN twice and I
On 2006-07-03, Roberto Padovani wrote:
> Here's what is dangerous with irq enabled:
>
> two = P6IN + P6IN;// or any other way in which you write directly to "two"
>
> beacuse you inevitably get 2 instructions that sequentially write at
> the memory address of "two":
If you only want "two" wr
Grant Edwards wrote:...
I'd like to point out that
1) I didn't write that code originally, I ran across that
example in a thread in the yahoo msp430 list.
2) The example isn't supposed to do anything useful, it's just
a simple test-case that demonstrates a bug in the compiler.
...
I didn'
quot;
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 3:35 PM
Subject: Re: [Mspgcc-users] Code generation question
> >> if you really want that single instruction as a function by itself and
> >> you want it to write directly in the global var
On 2006-07-03, David Brown wrote:
>> but in this case, reading the C source code, I honestly can't
>> understand for sure what it meantif I were to translate
>> manually that code into asm, I would have asked a
>> clarification to the programmer: did you want to sample twice
>> the port and t
On 2006-07-03, Roberto Padovani wrote:
> but in this case, reading the C source code, I honestly can't
> understand for sure what it meant
What it "meant" is irrelevent. There are rules that state
quite specifically how C source code is to be translated into
machine operations. For one of
- Original Message -
From: "Roberto Padovani"
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 3:35 PM
Subject: Re: [Mspgcc-users] Code generation question
> >> if you really want that single instruction as a function by itself
if you really want that single instruction as a function by itself and
you want it to write directly in the global variable, then you should
at least declare it naked.
Perhaps this is a case where we have misunderstood each other - as far as I
can tell, you said that Grant's code should be spli
- Original Message -
From: "John Pote"
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 1:11 PM
Subject: Re: [Mspgcc-users] Code generation question
> Hi everone,
>
> My thought on the following snippet from the prev mail:-
>
- Original Message -
From: "Roberto Padovani"
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 11:57 AM
Subject: Re: [Mspgcc-users] Code generation question
> Hi David,
>
> criticism is fineI'll explain my view.
>
>
Hi everone,
My thought on the following snippet from the prev mail:-
> By the way, I think it's also better to change your initial example:
>
> unsigned two;
> void foo(void)
> {
> two = P6IN + P6IN;
> }
>
> into:
>
> unsigned two;
>
> void foo(void)
> unsigned int tmp;
> {
> tmp = P6IN + P6I
Hi David,
criticism is fineI'll explain my view.
2006/7/3, David Brown :
I don't mean to sound patronising, but I don't think you are aware of what
compilers do, how they work, how "volatile" works, or how to write good C
code for embedded systems. I'm afraid your post is almost completely
ive critisism to aid
your better understanding. Thinking about these things is good, and
discussing them will refine that thinking.
- Original Message -
From: "Roberto Padovani"
To: "GCC for MSP430 - http://mspgcc.sf.net";
Sent: Monday, July 03, 2006 9:16 AM
Subject
knowing how a compiler works in the most unusual situations is always
interesting...and this discussion is no different.
however, a compiler is just a machine with a lot of rules, so you
cannot expect it to be "clever" anytime, even if correct code is a
necessity and efficiency is only a plus;
but
On 2006-06-30, Chris Liechti wrote:
Just for fun, I tried compiling the code with "two" changed to
an unsigned char. My mps430 compiler (3.2.3) then gives
mov.b &P6IN, r15
rla.b r15
mov.b r15, &two
ret
In other words, it makes the same mistak
Grant Edwards schrieb:
On 2006-06-30, Grant Edwards wrote:
On 2006-06-30, David Brown wrote:
Just for fun, I tried compiling the code with "two" changed to an unsigned
char. My mps430 compiler (3.2.3) then gives
mov.b &P6IN, r15
rla.b r15
mov.b r15, &two
ret
In other words,
On 2006-06-30, Grant Edwards wrote:
> On 2006-06-30, David Brown wrote:
>
>> Just for fun, I tried compiling the code with "two" changed to an unsigned
>> char. My mps430 compiler (3.2.3) then gives
>>
>> mov.b &P6IN, r15
>> rla.b r15
>> mov.b r15, &two
>> ret
>>
>> In other word
Hi,
I experimented with IAR c-compiler for MSP430 (that came with eZ430-F2013).
Here is my source code:
#include "msp430x20x3.h"
int main(void)
{
signed char sc;
unsigned char uc;
signed int si;
unsigned int ui;
sc=P1IN+P1IN;
uc=P1IN+P1IN;
si=P1IN+P1IN;
ui=P1IN+P1I
On 2006-06-30, David Brown wrote:
> Just for fun, I tried compiling the code with "two" changed to an unsigned
> char. My mps430 compiler (3.2.3) then gives
>
> mov.b &P6IN, r15
> rla.b r15
> mov.b r15, &two
> ret
>
> In other words, it makes the same mistake you did and
> disreg
On 2006-06-30, Bodo Rzany wrote:
> Am Wed, 28 Jun 2006 19:59:27 + (UTC) schrieb Grant Edwards:
>> Can anybody explain the code generated for this function?
>>
>> #include
>>
>> unsigned two;
>>
>> void foo(void)
>> {
>> two = P6IN + P6IN;
>> }
>>
>> 21 foo:
>>
>> 26
> Am Fri, 30 Jun 2006 11:20:03 +0200 schrieb David Brown:
> >>
> >> mov.b &0x0034, r15
> >> add r15, r15
> >> mov r15, &two
> >> ret
> >
> > That would be wrong. PINB is declared volatile - the C code says it
should
> > be read twice, so it should be read twice by the generated assembly.
T
Am Fri, 30 Jun 2006 11:13:32 +0200 schrieb Robert Dominicus-Schleutermann:
> Bodo Rzany schrieb:
>> Am Wed, 28 Jun 2006 19:59:27 + (UTC) schrieb Grant Edwards:
>>
>>> Why isn't this correct?
>>>
>>> mov.b &0x0034, r15
>>> mov.b &0x0034, r14
>>> add r15, r14
>>> mov
Am Fri, 30 Jun 2006 11:20:03 +0200 schrieb David Brown:
>>
>> mov.b &0x0034, r15
>> add r15, r15
>> mov r15, &two
>> ret
>
> That would be wrong. PINB is declared volatile - the C code says it should
> be read twice, so it should be read twice by the generated assembly. Thus
> better code
- Original Message -
From: "Bodo Rzany"
To:
Sent: Friday, June 30, 2006 10:57 AM
Subject: Re: [Mspgcc-users] Code generation question
> Am Wed, 28 Jun 2006 19:59:27 + (UTC) schrieb Grant Edwards:
> > Can anybody explain the code generated for this functio
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
Hello all!
Bodo Rzany schrieb:
> Am Wed, 28 Jun 2006 19:59:27 + (UTC) schrieb Grant Edwards:
>> Can anybody explain the code generated for this function?
>>
>> #include
>>
>> unsigned two;
>>
>> void foo(void)
>> {
>> two = P6IN + P6IN;
>> }
>>
Am Wed, 28 Jun 2006 19:59:27 + (UTC) schrieb Grant Edwards:
> Can anybody explain the code generated for this function?
>
> #include
>
> unsigned two;
>
> void foo(void)
> {
> two = P6IN + P6IN;
> }
>
> 21 foo:
>
> 26 5F42 3400 mov.b &0x0034, r15
> 27
Can anybody explain the code generated for this function?
#include
unsigned two;
void foo(void)
{
two = P6IN + P6IN;
}
21foo:
26 5F42 3400 mov.b &0x0034, r15
27 0004 4E4F mov.b r15, r14
28 0006 5F42 3400 mov.b
28 matches
Mail list logo
