Re: Accessing 20-bit memory range - issues with indirect addressing mode

look at the actual code generated

see what the difference in the actual code is


>From cPhone


> On May 4, 2014, at 1:14 PM, Tomek Lorek <[email protected]> wrote:
> 
> 2014-05-04 22:04 GMT+02:00 Tomek Lorek <[email protected]>:
>> 1. Possibly the main reason my code did not work was using
>> __asm__ __volatile__ ("movx #0, @%0"::"r"(flash));
>> instead of
>> __asm__ __volatile__ ("movx.b %1, @%0":"=r"(flash):"m"(Byte));
>> 
>> But I don't understand why the latter works and the first doesn't (the
>> 1st one causes "tilib: MSP430_State: Internal error (error = 68)" in
>> mspdebug right after stopping the program execution.
> 
> Just checked the flashdump diff right before and after executing the
> program - "movx #0, @%0"::"r"(flash))" variant messed up the flash
> bank A from where I was running the code and it erased 0xc400 instead
> of 0x1c400.
> Do you have any idea why?
> 
> The code is:
> unsigned long flash_addr = 0x1c400;
> unsigned int flash;
> unsigned int sr;
> 
> FCTL3 = FWKEY; // Clear Lock bit
> while (FCTL3 & BUSY) ;
> FCTL1 = FWKEY + MERAS; // Set MERAS bit
> 
> __asm__ __volatile__ ("mov r2,%0":"=r"(sr):);
> _DINT();
> __asm__ __volatile__ ("movx.a %1,%0":"=r"(flash):"m"(flash_addr));
> __asm__ __volatile__ ("movx #0, @%0"::"r"(flash));               // <-
> the line that is under discussion
> 
> __asm__ __volatile__ ("mov r2,%0":"=r"(sr):); // save SR before disabling IRQ
> __dint();
> 
> while (FCTL3 & BUSY) ; // test busy
> FCTL1 = FWKEY; // Clear MERAS bit
> FCTL3 = FWKEY + LOCK; // Set LOCK bit
> 
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