FS#12370: Initial RDS support for Si4701/Si4703 tuner (beast and clip zip)

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31346 a1c6a512-1295-4272-9138-f99709370657

firmware/drivers/rds.c

@@ -0,0 +1,192 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (c) 2011 by Bertrik Sikken
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+#include <strlcpy.h>
+#include "rds.h"
+
+/* programme identification */
+static uint16_t pi;
+/* program service name */
+static char ps_data[9];
+static char ps_copy[9];
+static int ps_segment;
+/* radio text */
+static char rt_data[65];
+static char rt_copy[65];
+static int rt_segment;
+static int rt_abflag;
+
+/* resets the rds parser */
+void rds_reset(void)
+{
+    ps_copy[0] = '\0';
+    ps_segment = 0;
+    rt_copy[0] = '\0';
+    rt_segment = 0;
+    pi = 0;
+}
+
+/* initialises the rds parser */
+void rds_init(void)
+{
+    rds_reset();
+}
+
+/* handles a group 0 packet, returns true if a new message was received */
+static bool handle_group0(uint16_t data[4])
+{
+    int segment, pos;
+
+    segment = data[1] & 3;
+
+    /* reset parsing if not in expected order */
+    if (segment != ps_segment) {
+        ps_segment = 0;
+        if (segment != 0) {
+            return false;
+        }
+    }
+
+    /* store data */
+    pos = segment * 2;
+    ps_data[pos++] = (data[3] >> 8) & 0xFF;
+    ps_data[pos++] = (data[3] >> 0) & 0xFF;
+    if (++ps_segment == 4) {
+        ps_data[pos] = '\0';
+        if (strcmp(ps_copy, ps_data) != 0) {
+            /* we got an updated message */
+            strcpy(ps_copy, ps_data);
+            return true;
+        }
+    }
+    return false;
+}
+
+/* handles a radio text characters, returns true if end-of-line found */
+static bool handle_rt(int pos, char c)
+{
+    switch (c) {
+    case 0x0A:
+        /* line break hint */
+        rt_data[pos] = ' ';
+        return false;
+    case 0x0D:
+        /* end of line */
+        rt_data[pos] = '\0';
+        return true;
+    default:
+        rt_data[pos] = c;
+        return false;
+    }
+}
+
+/* handles a group 2 packet, returns true if a new message was received */
+static bool handle_group2(uint16_t data[4])
+{
+    int abflag, segment, version, pos;
+    bool done;
+    
+    /* reset parsing if not in expected order */
+    abflag = (data[1] >> 4) & 1;
+    segment = data[1] & 0xF;
+    if ((abflag != rt_abflag) || (segment != rt_segment)) {
+        rt_abflag = abflag;
+        rt_segment = 0;
+        if (segment != 0) {
+            return false;
+        }
+    }
+
+    /* store data */
+    version = (data[1] >> 11) & 1;
+    done = false;
+    if (version == 0) {
+        pos = segment * 4;
+        done = done || handle_rt(pos++, (data[2] >> 8) & 0xFF);
+        done = done || handle_rt(pos++, (data[2] >> 0) & 0xFF);
+        done = done || handle_rt(pos++, (data[3] >> 8) & 0xFF);
+        done = done || handle_rt(pos++, (data[3] >> 0) & 0xFF);
+    } else {
+        pos = segment * 2;
+        done = done || handle_rt(pos++, (data[3] >> 8) & 0xFF);
+        done = done || handle_rt(pos++, (data[3] >> 0) & 0xFF);
+    }
+    if ((++rt_segment == 16) || done) {
+        rt_data[pos] = '\0';
+        if (strcmp(rt_copy, rt_data) != 0) {
+            /* we got an updated message */
+            strcpy(rt_copy, rt_data);
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/* processes one rds packet, returns true if a new message was received */
+bool rds_process(uint16_t data[4])
+{
+    int group;
+
+    /* get programme identification */
+    if (pi == 0) {
+        pi = data[0];
+    }
+    
+    /* handle rds data based on group */
+    group = (data[1] >> 11) & 0x1F;
+    switch (group) {
+    
+    case 0: /* group 0A: basic info */
+    case 1: /* group 0B: basic info */
+        return handle_group0(data);
+    
+    case 4: /* group 2A: radio text */
+    case 5: /* group 2B: radio text */
+        return handle_group2(data);
+    
+    default:
+        break;
+    }
+
+    return false;
+}
+
+/* returns the programme identification code */
+uint16_t rds_get_pi(void)
+{
+    return pi;
+}
+
+/* returns the most recent valid programme service name */
+char* rds_get_ps(void)
+{
+    return ps_copy;
+}
+
+/* returns the most recent valid RadioText message */
+char* rds_get_rt(void)
+{
+    return rt_copy;
+}
+