1 files changed, 76 insertions, 0 deletions
diff --git a/src/cmd/scat/bitinput.c b/src/cmd/scat/bitinput.c
new file mode 100644
index 00000000..b4bd286b
--- /dev/null
+++ b/src/cmd/scat/bitinput.c
@@ -0,0 +1,76 @@
+#include	<u.h>
+#include	<libc.h>
+#include	<bio.h>
+#include	"sky.h"
+
+static int hufvals[] = {
+	 1,  1,  1,  1,  1,  1,  1,  1,
+	 2,  2,  2,  2,  2,  2,  2,  2,
+	 4,  4,  4,  4,  4,  4,  4,  4,
+	 8,  8,  8,  8,  8,  8,  8,  8,
+	 3,  3,  3,  3,  5,  5,  5,  5,
+	10, 10, 10, 10, 12, 12, 12, 12,
+	15, 15, 15, 15,  6,  6,  7,  7,
+	 9,  9, 11, 11, 13, 13,  0, 14,
+};
+
+static int huflens[] = {
+	3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3,
+	4, 4, 4, 4, 4, 4, 4, 4,
+	4, 4, 4, 4, 4, 4, 4, 4,
+	4, 4, 4, 4, 5, 5, 5, 5,
+	5, 5, 5, 5, 5, 5, 6, 6,
+};
+
+static	int	buffer;
+static	int	bits_to_go;		/* Number of bits still in buffer */
+
+void
+start_inputing_bits(void)
+{
+	bits_to_go = 0;
+}
+
+int
+input_huffman(Biobuf *infile)
+{
+	int c;
+
+	if(bits_to_go < 6) {
+		c = Bgetc(infile);
+		if(c < 0) {
+			fprint(2, "input_huffman: unexpected EOF\n");
+			exits("format");
+		}
+		buffer = (buffer<<8) | c;
+		bits_to_go += 8;
+	}
+	c = (buffer >> (bits_to_go-6)) & 0x3f;
+	bits_to_go -= huflens[c];
+	return hufvals[c];
+}
+
+int
+input_nybble(Biobuf *infile)
+{
+	int c;
+
+	if(bits_to_go < 4) {
+		c = Bgetc(infile);
+		if(c < 0){
+			fprint(2, "input_nybble: unexpected EOF\n");
+			exits("format");
+		}
+		buffer = (buffer<<8) | c;
+		bits_to_go += 8;
+	}
+
+	/*
+	 * pick off the first 4 bits
+	 */
+	bits_to_go -= 4;
+	return (buffer>>bits_to_go) & 0x0f;
+}