[OpenBIOS] [PATCH 2/6] ppc: add Adler-32 checksum capability
Cormac O'Brien
i.am.cormac.obrien at gmail.com
Sat Jun 20 19:48:58 CEST 2015
This patch provides an implementation of the adler32 Forth word as required by
Mac OS 9 and BootX.
Signed-off-by: Cormac O'Brien <i.am.cormac.obrien at gmail.com>
---
arch/ppc/qemu/init.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
index 4fe8b72..5cc45ae 100644
--- a/arch/ppc/qemu/init.c
+++ b/arch/ppc/qemu/init.c
@@ -680,6 +680,60 @@ static void ffilll(void)
}
}
+/*
+ * adler32 ( adler buf len -- checksum )
+ *
+ * Adapted from Mark Adler's original implementation (zlib license)
+ *
+ * Both OS 9 and BootX require this word for payload validation.
+ */
+
+#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 = (uint32_t)POP();
+ char *buf = (char *)POP();
+ uint32_t adler = (uint32_t)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 +999,9 @@ arch_of_init(void)
/* Implementation of filll word (required by BootX) */
bind_func("filll", ffilll);
+
+ /* Implementation of adler32 word (required by OS 9, BootX) */
+ bind_func("adler32", adler32);
bind_func("platform-boot", boot);
bind_func("(go)", go);
--
2.4.4
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