20060303-partial

1 files changed, 23 insertions, 0 deletions

diff --git a/module/crc.m b/module/crc.m
new file mode 100644
index 00000000..408af38e
--- /dev/null
+++ b/module/crc.m
@@ -0,0 +1,23 @@
+Crc: module
+{
+	PATH: con "/dis/lib/crc.dis";
+
+	CRCstate: adt {
+		crc: int;
+		crctab: array of int;
+		reg: int;
+	};
+
+	# setup crc table with given polynomial (if 0 default polynomial used) 
+	# (the polynomial has an implicit top bit set)
+	# reg is the initial value of the CRC register 
+	# (usually 0 but 16rfffffffrf in the CRC32 algorithm for example)
+	init: fn(poly: int, reg: int): ref CRCstate;
+
+	# calculate crc of first nb bytes in given array of bytes and return its value
+	# may be called repeatedly to calculate crc of a series of arrays of bytes
+	crc :	fn(state: ref CRCstate, buf: array of byte, nb: int): int;
+
+	# reset crc state to its initial value
+	reset: fn(state: ref CRCstate);
+};