Re: [OpenBIOS] [PATCH] Add tbu@ and tbl@ words

[Programmingkid]

> On Dec 29, 2017, at 8:01 PM, BALATON Zoltan  wrote:
>
> I've tried to implement it the way I've suggested and came up with the 
> patch below, but it does not seem to work. I think this is because the 
> arithmetic in get-msec overflows and does not get the right values. Could 
> it be it works in SLOF because that runs on 64bit? Or is something needed 
> to tell Forth to use 64bit values on PPC32? Any ideas?
>
> Regards,
> BALATON Zoltan
>
> diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
> index b0c0cfc..4c8631a 100644
> --- a/arch/ppc/qemu/init.c
> +++ b/arch/ppc/qemu/init.c
> @@ -793,6 +793,20 @@ static void adler32(void)
>     RET(s2 << 16 | s1);
> }
>
> +/*
> Get time base value from CPU
> */
>
> +static void tb_fetch(void)
> +{
> unsigned long tbl, tbu;

I would change "unsigned long" to uint32_t.
> do {
>  tbu = mftbu();
>  tbl = mftb();
> } while (tbu != mftbu());
> DPUSH(((uint64_t)tbu << 32) | tbl);

I suspect this line is the problem. I had a lot of problems trying to do this exact bit operation. I gave up on it and instead did it another way. That patch was sent to the list.
> +}
>
> void
> arch_of_init(void)
> {
> @@ -1062,7 +1076,9 @@ arch_of_init(void)
> /* Implementation of adler32 word (required by OS 9, BootX) */
> bind_func("(adler32)", adler32);
> fword("fixup-tbfreq");
> bind_func("(tb@)", tb_fetch);
> bind_func("platform-boot", boot);
> bind_func("(arch-go)", arch_go);
>
> }
> diff --git a/arch/ppc/qemu/qemu.fs b/arch/ppc/qemu/qemu.fs
> index d683421..1e3e0cb 100644
> --- a/arch/ppc/qemu/qemu.fs
> +++ b/arch/ppc/qemu/qemu.fs
> @@ -139,3 +139,34 @@ variable keyboard-phandle 0 keyboard-phandle !
>     3drop 0
>   then
> ;
>
> +\ -------------------------------------------------------------------------
> +\ time base related words
> +\ -------------------------------------------------------------------------
>
> +1 value tb-frequency
>
> +: fixup-tbfreq
> " /cpus/@0" find-device
> " timebase-frequency" active-package get-package-property IF
> 2drop
> ELSE
> decode-int to tb-frequency 2drop
> THEN
> device-end
>
> +;
>
> +: tb@ ( -- tbval)
> " (tb@)" $find if
> execute
> 20 lshift swap ffffffff and or
> else
> 2drop 0
> then
>
> +;
>
> +: get-msecs ( -- ms ) tb@ d# 1000 * tb-frequency / ;
> +: get-usecs ( -- us ) tb@ d# 1000000 * tb-frequency / ;
>
> +: ms ( ms-to-wait -- ) get-msecs + BEGIN get-msecs over >= UNTIL drop ;
> +: us  ( us-to-wait -- )  get-usecs +  BEGIN get-usecs over >= UNTIL  drop ;
> diff --git a/include/arch/ppc/processor.h b/include/arch/ppc/processor.h
> index bb03bb1..5e79ba8 100644
> --- a/include/arch/ppc/processor.h
> +++ b/include/arch/ppc/processor.h
> @@ -462,6 +462,20 @@ static inline void slbmte(unsigned long rs, unsigned long rb)
>     asm volatile("slbmte %0,%1 ; isync" :: "r" (rs), "r" (rb) : "memory");
> }

I would replace all the "unsigned long" with uint32_t here.
> +static inline unsigned long mftb(void)
> +{
> unsigned long val;
> asm volatile("mftb %0" : "=r" (val));
> return val;
>
> +}
>
> +static inline unsigned long mftbu(void)
> +{
> unsigned long val;
> asm volatile("mftbu %0" : "=r" (val));
> return val;
>
> +}
>
> #endif /* !__ASSEMBLER__ */
>
> #endif   /* _H_PROCESSOR */