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authorBdale Garbee <bdale@gag.com>2012-09-12 20:01:22 -0600
committerBdale Garbee <bdale@gag.com>2012-09-12 20:01:22 -0600
commit3b612efcd1dddc6a3d59012f7ed57754b1f798c2 (patch)
tree18d50713491ef96c5c127a309f870efb6c33f98d /src/core/ao_freq.c
parente076773c1693e2a62bb828dee71c04c20dbab0a5 (diff)
parent01eb36408d7e0e826b431fcc1d3b2deb23607e0b (diff)
Merge branch 'new-debian' into debian
Conflicts: ChangeLog debian/altos.install debian/changelog debian/control debian/copyright debian/dirs debian/docs debian/menu debian/rules src/Makefile
Diffstat (limited to 'src/core/ao_freq.c')
-rw-r--r--src/core/ao_freq.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/src/core/ao_freq.c b/src/core/ao_freq.c
new file mode 100644
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--- /dev/null
+++ b/src/core/ao_freq.c
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+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+
+/*
+ * The provided 'calibration' value is
+ * that needed to tune the radio to precisely 434550kHz.
+ * Use that to 'walk' to the target frequency by following
+ * a 'bresenham' line from 434550kHz to the target
+ * frequency, and updating the radio setting along the way
+ */
+
+int32_t ao_freq_to_set(int32_t freq, int32_t cal) __reentrant
+{
+ static __pdata int32_t set;
+ static __pdata uint8_t neg;
+ static __pdata int32_t error;
+
+ set = 0;
+ neg = 0;
+ error = -434550 / 2;
+
+ if ((freq -= 434550) < 0) {
+ neg = 1;
+ freq = -freq;
+ }
+ for (;;) {
+ if (error > 0) {
+ error -= 434550;
+ set++;
+ } else {
+ error += cal;
+ if (--freq < 0)
+ break;
+ }
+ }
+ if (neg)
+ set = -set;
+ return cal + set;
+}