[OpenBIOS] [PATCH 2/2] add Adler-32 checksum capability

[Cormac O'Brien]

From: Cormac O'Brien <cormac at c-obrien.org>

This patch adds Adler-32 checksum functionality to the Forth interpreter as
required by the Mac OS 9 boot script. This code might belong somewhere else,
do let me know.

---
 libopenbios/bootinfo_load.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/libopenbios/bootinfo_load.c b/libopenbios/bootinfo_load.c
index fcb23ea..d0ccd89 100644
--- a/libopenbios/bootinfo_load.c
+++ b/libopenbios/bootinfo_load.c
@@ -30,6 +30,54 @@
     do { } while (0)
 #endif
 
+/* adler32 -- 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);
+
+void
+adler32( void ) {
+    unsigned int len = POP();
+    char *buf = POP();
+    unsigned long adler = POP();
+
+    if (buf == NULL) {
+        RET(-1);
+    }
+
+    long base = 65521L;
+    int nmax = 5552;
+
+    unsigned long s1 = adler & 0xffff;
+    unsigned long s2 = (adler >> 16) & 0xffff;
+    int 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);
+}
+
 static char *
 get_device( const char *path )
 {
@@ -255,6 +303,7 @@ bootinfo_init_program(void)
 	/* If the payload is bootinfo then we execute it immediately */
 	if (scriptvalid) {
 		DPRINTF("bootscript: %s\n", bootscript);
+		bind_func("adler32", adler32);
 		feval(bootscript);
 	}
 	else
-- 
2.3.4