Lpc2000

Tom,

Are you saying that with the (packed) attribute, the
compiler will treat the number as 16bits where given
the orginal poster's definition the struct would be
32bits?  Now if the register were treated as 32bits,
would this cause a problem? 

--- Tom Walsh <tom@...> wrote:

> ????????? ??????? wrote:
> 
> >On Tue, 08 Nov 2005 04:47:49 -0500
> >  Tom Walsh <tom@...> wrote:
> >  
> >
> >>vaneenbergen wrote:
> >>
> >>    
> >>
> >>>That the first bit of the second byte also
> changed is very possible. 
> >>>This is de to the processor. The timer register
> should be handled in 
> >>>a 32 bit access. this is what i found out. so
> instead of these kind 
> >>>of structures i just handle them in 32-bit. this
> way it is also 
> >>>quicker, you can change all values at the same
> time.
> >>>
> >>>is this really the fault of the compiler?????
> >>> 
> >>>
> >>>      
> >>>
> >>He didn't understand what it was that he wrote so
> how can he answer 
> >>that 
> >>question?
> >>
> >>
> >>TomW
> >>
> >>    
> >>
> >
> >What you mean? I think it obviously, that it's
> really fault of 
> >compiler. I explain my point of view to Paul
> >  
> >
> Okay, while washing some dishes in the kitchen, I
> finally realized that 
> you skipped ahead to blame the compiler and were
> convinced that your 
> code is correct.  It is not.
> 
> I believe, and correct me if I am wrong, that what
> you were trying to do 
> was to describe the T0MCR register so that you could
> access it and 
> change values???
> 
> If so, here is what you should have done:
> 
> ================= packed struct ===================
> typedef struct __attribute__ ((packed))
> {
> __REG32 MR0I :1;
> __REG32 MR0R :1;
> __REG32 MR0S :1;
> 
> __REG32 MR1I :1;
> __REG32 MR1R :1;
> __REG32 MR1S :1;
> 
> __REG32 MR2I :1;
> __REG32 MR2R :1;
> __REG32 MR2S :1;
> 
> __REG32 MR3I :1;
> __REG32 MR3R :1;
> __REG32 MR3S :1;
> __REG32 :4;
> } __txmcr_bits;
> 
> #define T0MCRbits (*(volatile __txmcr_bits
> *)0xE0004014)
> 
> ===================== snip =======================
> 
> The volatile can stay, it is harmless.  What is key
> is the 
> "__attribute__ ((packed))" keyphrase.  What that
> means is that the 
> padding between elements of the structure is to be
> removed.  If you say 
> this:
> 
> =============== begin ===============
> 
> struct FLESHY {
>     long    foo;
>     char   bar;
>     long   done;
> };
> 
> struct SMALLER {
>     long    foo;
>     char   bar;
>     long   done;
> } __attribute__ ((packed));
> 
> struct FLESHY bean;
> 
> struct SMALLER soup;
> 
> ============== snip ================
> 
> You will find that "bean" is 12 bytes and "soup" is
> 9 bytes...  This is 
> because the structure has been packed, all the "air"
> has been removed.  
> ok?  Try it, do a printf ("%d\n", sizeof(bean)) and
> a printf("%d\n", 
> sizeof(soup)).
> 
> Now, what you said was this:  "MR01 is significant
> to 1 bit and is 
> aligned on a 32 bit boundry".
> 
> gcc did not do it "wrong", you just did not read
> what you told it.  The 
> compiler did exactly what you told it to do.
> 
> Look at this, this is my definition of the RTCTCR
> registers of the LPC2138:
> 
> =========== begin ================
> typedef struct __attribute__ ((packed))
> {
>     uint    seconds:6;
>     uint    reserved:2;
>     uint    minutes:6;
>     uint    reserved1:2;
>     uint    hours:5;
>     uint    reserved2:3;
>     uint    dayOfWeek:3;
>     uint    reserved3:5;
> } rtcCTIME0_t;
> 
> typedef struct __attribute__ ((packed)) {
>     uint    dayOfMonth:5;
>     uint    reserved:3;
>     uint    month:4;
>     uint    reserved1:4;
>     uint    year:12;
>     uint    reserved2:4;
> } rtcCTIME1_t;
> 
> typedef struct __attribute__ ((packed)) {
>     uint    dayOfYear:12;
>     uint    reserved:20;
> } rtcCTIME2_t;
> 
> 
> typedef struct
> {
>   REG_8 ilr;            // Interrupt Location
> Register
>   REG_8 _pad0[3];
>   REG16 ctc;            // Clock Tick Counter
>   REG16 _pad1;
>   REG_8 ccr;            // Clock Control Register
>   REG_8 _pad2[3];
>   REG_8 ciir;            // Counter Increment
> Interrupt Register
>   REG_8 _pad3[3];
>   REG_8 amr;            // Alarm Mask Register
>   REG_8 _pad4[3];
>   rtcCTIME0_t ctime0;            // Consolidated
> Time Register 0
>   rtcCTIME1_t ctime1;            // Consolidated
> Time Register 1
>   rtcCTIME2_t ctime2;            // Consolidated
> Time Register 2
>   REG_8 sec;            // Seconds Register
>   REG_8 _pad5[3];
>   REG_8 min;            // Minutes Register
>   REG_8 _pad6[3];
>   REG_8 hour;            // Hours Register
>   REG_8 _pad7[3];
>   REG_8 dom;            // Day Of Month Register
>   REG_8 _pad8[3];
>   REG_8 dow;            // Day Of Week Register
>   REG_8 _pad9[3];
>   REG16 doy;            // Day Of Year Register
>   REG16 _pad10;
>   REG_8 month;            // Months Register
>   REG_8 _pad11[3];
>   REG16 year;            // Years Register
>   REG32 _pad12[8];
>   REG_8 alsec;            // Alarm Seconds Register
>   REG_8 _pad13[3];
>   REG_8 almin;            // Alarm Minutes Register
>   REG_8 _pad14[3];
>   REG_8 alhour;        // Alarm Hours Register
>   REG_8 _pad15[3];
>   REG_8 aldom;            // Alarm Day Of Month
> Register
> 
=== message truncated ===



	
		
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