Re: [OpenBIOS] [PATCH] init: add Adler-32 checksum support

[Andreas Färber]

Am 19.04.2015 um 20:07 schrieb Cormac O'Brien:
> From: Cormac O'Brien

Not sure how strict we take this for OpenBIOS these days, but I notice
that you haven't signed this off. You mention below another
implementation - what license is that under, and did you copy code or
just the algorithm? Would be worth a mention in the commit message.
> arch/ppc/qemu/init.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
>
> diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
> index 4fe8b72..f9989ed 100644
> --- a/arch/ppc/qemu/init.c
> +++ b/arch/ppc/qemu/init.c
> @@ -680,6 +680,57 @@ static void ffilll(void)
>      }   
>  }
>
> +/* adler32     (len buf adler -- checksum)
> Adapted from Mark Adler's zlib implementation */

FWIW this end-of-comment looks unusual...
> +#define DO1(buf,i)  {s1 += buf[i]; s2 += s1;}
> +#define DO2(buf,i)  DO1(buf,i); DO1(buf,i+1);
> +#define DO4(buf,i)  DO2(buf,i); DO2(buf,i+2);
> +#define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
> +#define DO16(buf)   DO8(buf,0); DO8(buf,8);
>
> +static void adler32(void)
> +{
> uint32_t len = POP();
> char *buf = POP();
> uint32_t adler = POP();
> if (buf == NULL) {
>    RET(-1);
> }
> uint32_t base = 65521;
> uint32_t nmax = 5552;
> uint32_t s1 = adler & 0xffff;
> uint32_t s2 = (adler >> 16) & 0xffff;
> uint32_t k;
> while (len > 0) {
>    k = (len < nmax ? len : nmax);
>    len -= k;
>    while (k >= 16) {
>        DO16(buf);
>        buf += 16;
>        k -= 16;
>    }
>    if (k != 0) {
>        do {
>            s1 += *buf++;
>            s2 += s1;
>        } while (--k);
>    }
>    s1 %= base;
>    s2 %= base;
> }
> RET(s2 << 16 | s1);
>
> +}
>
> void
>  arch_of_init(void)
>  {
> @@ -945,6 +996,9 @@ arch_of_init(void)
>  /* Implementation of filll word (required by BootX) */
>  bind_func("filll", ffilll);
> /* Implementation of Adler-32 required by Mac OS 9 */
> bind_func("adler32", adler32);

I know OpenBIOS is inconsistent at this in places, but please make sure
the two lines you add use the same indentation. :) Surrounding lines
seem to use four spaces, not tabs.
>  bind_func("platform-boot", boot);
>  bind_func("(go)", go);

Regards,
Andreas