--- a/src/cs/layer1/tpu_drivers/source0/tpudrv10.c	Sat Jan 20 00:03:02 2018 +0000
+++ b/src/cs/layer1/tpu_drivers/source0/tpudrv10.c	Sat Jan 20 00:37:48 2018 +0000
@@ -306,23 +306,15 @@
     synth_900,  magic1_900,  magic2_rx900},
 };
 
-/*
- * Leonardo tpudrv12.obj contains a function named calc_a_b(); there is
- * no such function in the LoCosto version, but there is a similar-looking
- * calc_rf_freq() function instead.  Let's try making our calc_a_b()
- * from LoCosto's calc_rf_freq().
- */
-
-#if 0
-UWORD32 calc_a_b(UWORD16 arfcn, UWORD8 downlink)
+static UWORD32 calc_freq_prog(UWORD16 arfcn, UWORD8 downlink)
 {
   UWORD32 farfcn;	/* sp+0x1C, in 200 kHz units */
-  struct synth_s  *s;
-  struct magic1_s *m1;
-  struct magic2_s *m2;
+  const struct synth_s  *s;
+  const struct magic1_s *m1;
+  const struct magic2_s *m2;
   UWORD32 magic1;	/* sp+0x24 */
   UWORD16 sp4;
-  UWORD32 sp0x14, sp0x18, sp0x20;
+  UWORD32 sp8, sp0xC, sp0x10, sp0x14, sp0x18, sp0x20;
 
   s = rf_path[rf_index].synth;
   while(s->limit < arfcn)
@@ -353,16 +345,12 @@
     m2++;
   magic2_byte = (m2->magic & 7) << 5;
 
-  rf_chip_band = s->rf_chip_band;
+  sp8 = (sp0x14 / 16) >> 21;
+  sp0xC = sp0x14 - (sp8 << 25);
+  sp0x10 = (((sp8 << 4) + sp0xC) * 0x1A00000 - 0x18) >> 21;
 
-  // Convert the ARFCN to the channel frequency (times 5 to avoid the decimal value)
-  farfcn = 5*s->tx_rx[downlink].farfcn0 + (arfcn - s->arfcn0);
-  n = farfcn * s->tx_rx[downlink].ou;
-
-  /* magic A & B encoding for Rita */
-  return((n - 4096) << 3);
+  return ((sp0xC & 0xF) << 12) | ((sp8 & 0x7F) << 16) | ((sp0x10 & 0xF) << 8);
 }
-#endif
 
 /*------------------------------------------*/
 /*          Convert_l1_radio_freq           */