1 files changed, 101 insertions, 0 deletions
diff --git a/teletext.h b/teletext.h
new file mode 100644
index 0000000..fa1b519
--- /dev/null
+++ b/teletext.h
@@ -0,0 +1,101 @@
+
+#ifndef __TS_TELETEXT_H
+#define __TS_TELETEXT_H
+
+
+#define PACK  __attribute__ ((__packed__))
+
+struct ttxt_pes_header {
+  uint8_t start[3];
+  uint8_t stream_id  PACK;
+  uint16_t len PACK;
+
+  // private_stream_1 packets (and others)
+  uint8_t flags[2] PACK;
+  uint8_t header_len PACK;
+};
+
+
+enum {
+  ttxt_non_subtitle = 2,
+  ttxt_subtitle = 3,
+  ttxt_stuff = 0xff
+};
+
+#define TTXT_LINE_NO(x) ((x).par_loff & 0x1f)
+struct ttxt_data_field {
+  uint8_t data_unit_id PACK;
+  uint8_t data_unit_length PACK;
+  uint8_t par_loff PACK;
+  uint8_t framing_code PACK;
+  uint8_t mag_addr_ham[2] PACK;
+  uint8_t data[40] PACK;
+};
+
+
+struct ttxt_pes_data_field {
+  uint8_t data_identifier PACK;
+  struct ttxt_data_field d[1] PACK;
+};
+
+
+// Really 25 + row 0
+#define TTXT_DISPLAYABLE_ROWS 26
+
+enum pageflags {
+  erasepage = 0x01,
+  newsflash = 0x02,
+  subtitle = 0x04,
+  suppress_header = 0x08,
+  inhibit_display = 0x10 // rows 1 - 24 are not to be displayed
+};
+
+struct ttxt_page {
+  uint8_t mag;
+  uint8_t no;
+  uint8_t flags;
+  uint8_t national_charset;
+  uint8_t data[TTXT_DISPLAYABLE_ROWS][40];
+};
+
+// FROM vbidecode
+// unham 2 bytes into 1, report 2 bit errors but ignore them
+unsigned char unham(unsigned char a,unsigned char b);
+
+#define UNHAM_INV(a, b) unham(invtab[a], invtab[b])
+
+// ham 8/4 the byte in into two bytes pointed to by out
+void ham8_4byte(uint8_t in, uint8_t *out);
+// ham 8/4 the nibble in into the byte pointed to by out
+uint8_t ham8_4nibble(uint8_t in);
+
+// odd parity status for last 7 bits of byte 
+int parity(uint8_t x);
+
+/*
+ * Map Latin G0 teletext characters into a ISO-8859-1 approximation.
+ * Trying to use similar looking or similar meaning characters.
+ * Gtriplet - 4 bits = triplet-1 bits 14-11 (14-8) of a X/28 or M/29 packet, if unknown - use 0
+ * natopts - 3 bits = national_options field of a Y/0 packet (or triplet-1 bits 10-8 as above?)
+ * inchar - 7 bits = characted to remap
+ * Also strips parity
+ */
+uint8_t ttxt_laG0_la1_char(int Gtriplet, int natopts, uint8_t inchar);
+
+/*
+ * Map Latin G2 teletext characters into a ISO-8859-1 approximation.
+ * Trying to use similar looking or similar meaning characters.
+ */
+uint8_t ttxt_laG2_la1_char(uint8_t inchar);
+
+
+
+// debug stuff
+void print_page(struct ttxt_page *p);
+void print_line(char *p);
+void dump_hex(char *msg, const uint8_t *p, int len);
+
+// invert tab for last 42 bytes in packets
+extern unsigned char invtab[256];
+
+#endif __TS_TELETEXT_H