I think, that the guy who writes th code should be prior to compiler
So if I say
(int)x * (int)144
I think it should be simple to the compiler to
understand what I want. But mspgcc wants to be smarter, and thats bad.
I rewritten code in asm, it works with all int's and it saves 50 bytes of
flash.
robert
On Friday 28 of May 2004 08:34, Dima wrote:
> > 1. Can anyone see reason why is push r2, and pop SR. Is it for fun?
>
> These are disassembly tricks. Compile your source with -S flag then see
> _pure_ assembly.
>
> > 2. has anyone found in early math lessons, that 144 = -112 !!!?
>
> You already answered your question below.
>
> > I fully understand, that 112+144 = 256. I also understand, that 2+2=4
>
> This might be an answer.
>
> > But these are not what states in C.
>
> they are.
>
> > Funny is that if constant is below 126 everything is OK.
> > casting to int doesn't help
> > I am used to write HW mul myself but after 1 year and many updates I
> > thought somebody has fixed it up.
>
> t= usart0_rx_buffer[usart0_rx_extract_idx]*144;
> mov #642, r13 ;#0x0282
> mov &0x026c,r15 ;src addr 0x026c
> add r13, r15 ;
> push r2 ;
> dint
> nop
> mov.b @r15, &0x0130 ;
> mov.b #0, &0x0131 ;subst r3 with As==00
> mov #-112, &0x0138 ;#0xff90
> mov.b #0, &0x0139 ;subst r3 with As==00
>
> These two load second operand with int 144 (tricky, isn't it? :)
>
>
> mov &0x013a,r10 ;src addr 0x013a
> pop SR
> this is the same as pop r2 (disassembly tricks only!)
>
> > I have also suggestion to free(void* ptr) in malloc( which I am using
>
> for
>
> > ages. It helps me to free not only memory allocated via malloc, but
>
> also
>
> > pointers to memory in eeprom- which I directly use via pointer. I call
> >
> > free() without worring if deallocation is possible. I also must
>
> mention,
>
> > that first int after __noinit_end is used to store value of memory
>
> size
>
> > allocated with malloc.(*t)
> > So if p is not withing malloc range no action is taken.
>
> That's correct.
>
>
> void myfree (void *p)
> {
> size_t *t = &__noinit_end;
> if(((int)p < ((int)t +*t)) && ((int)p > (int)t)){
> p--;
> *t -= XSIZE(((size_t*)p));
> MARK_FREE (((size_t*)p));
> }
> }
>
>
> ~d
--
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Robert Seczkowski
rs...@poczta.onet.pl
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