[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 <cormac at c-obrien.org>
> 
> ---

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

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