Initial import

1 files changed, 61 insertions, 0 deletions

diff --git a/filter/faxd.h b/filter/faxd.h
new file mode 100644
index 00000000..886514f5
--- /dev/null
+++ b/filter/faxd.h
@@ -0,0 +1,61 @@
+/* Fax G3/G4 tables */
+
+/*
+<raph> the first 2^(initialbits) entries map bit patterns to decodes
+<raph> let's say initial_bits is 8 for the sake of example
+<raph> and that the code is 1001
+<raph> that means that entries 0x90 .. 0x9f have the entry { val, 4 }
+<raph> because those are all the bytes that start with the code
+<raph> and the 4 is the length of the code
+... if (n_bits > initial_bits) ...
+<raph> anyway, in that case, it basically points to a mini table
+<raph> the n_bits is the maximum length of all codes beginning with that byte
+<raph> so 2^(n_bits - initial_bits) is the size of the mini-table
+<raph> peter came up with this, and it makes sense
+*/
+
+typedef struct cfd_node_s cfd_node;
+
+struct cfd_node_s
+{
+	short val;
+	short nbits;
+};
+
+enum
+{
+	cfd_white_initial_bits = 8,
+	cfd_black_initial_bits = 7,
+	cfd_2d_initial_bits = 7,
+	cfd_uncompressed_initial_bits = 6	/* must be 6 */
+};
+
+/* non-run codes in tables */
+enum
+{
+	ERROR = -1,
+	ZEROS = -2, /* EOL follows, possibly with more padding first */
+	UNCOMPRESSED = -3,
+};
+
+/* semantic codes for cf_2d_decode */
+enum
+{
+	P = -4,
+	H = -5,
+	VR3 = 0,
+	VR2 = 1,
+	VR1 = 2,
+	V0 = 3,
+	VL1 = 4,
+	VL2 = 5,
+	VL3 = 6,
+};
+
+/* Decoding tables */
+
+extern const cfd_node cf_white_decode[];
+extern const cfd_node cf_black_decode[];
+extern const cfd_node cf_2d_decode[];
+extern const cfd_node cf_uncompressed_decode[];
+