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

[Programmingkid]

> On Dec 29, 2017, at 8:01 PM, BALATON Zoltan <balaton at eik.bme.hu> 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 */