[PATCH] init: add Adler-32 checksum support

[Cormac O'Brien]

From: Cormac O'Brien

---
 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 */
+
+#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);

bind_func("platform-boot", boot);
     bind_func("(go)", go);

[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

[Mark Cave-Ayland]

On 20/04/15 14:07, Andreas Färber wrote:
> 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.

According to Wikipedia (*ahem*), the zlib license is deemed
GPL-compatible so I don't believe the license should be an issue here.

ATB,

Mark.

[Tarl Neustaedter]

On 2015-Apr-20 15:39 , Mark Cave-Ayland wrote:
> According to Wikipedia (*ahem*), the zlib license is deemed
> GPL-compatible so I don't believe the license should be an issue here.

Please don't quote Wikipedia, quote the source it cites:

https://www.gnu.org/licenses/license-list.html#ZLib

According to *Gnu.org*, Zlib is compatible with the GPL.

[Mark Cave-Ayland]

On 20/04/15 20:42, Tarl Neustaedter wrote:
> On 2015-Apr-20 15:39 , Mark Cave-Ayland wrote:
> > According to Wikipedia (*ahem*), the zlib license is deemed
> > GPL-compatible so I don't believe the license should be an issue here.
>
> Please don't quote Wikipedia, quote the source it cites:
>
> https://www.gnu.org/licenses/license-list.html#ZLib
>
> According to *Gnu.org*, Zlib is compatible with the GPL.

Ha indeed - much better :)

ATB,

Mark.

[Mark Cave-Ayland]

On 19/04/15 19:07, Cormac O'Brien wrote:
> From: Cormac O'Brien
>
> 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)

I think this stack diagram is back-to-front?
> Adapted from Mark Adler's zlib implementation */
>
> +#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);
>
> bind_func("platform-boot", boot);
> bind_func("(go)", go);

One thing to think about here is the subject line: I'd probably go for a
"ppc:" or similar prefix in order for two reasons: firstly there is more
than one init.c in the codebase, and secondly it's easy to tell from the
git shortlog that this patch only affects PPC and no other architecture.

Possibly there are a few minor whitespace changes that need some
touching up, but I'm generally happy with the mechanics of this patch -
I think with these minor points taken care of and a Signed-off-by then
this is ready for commit.

ATB,

Mark.