gsm0508: add functions to calculate beginning of a block

The calculation of the beginning of a block for TCH/F, TCH/H and FACCH
can be challenging since those channels are affected by the diagonal
interleaving of the TCH channels. However, GSM 05.02 Section 7 Table 1
of 5 specifies how the blocks are distributed over the TDMA frame
interval. Lets add a mapping function that is based on that table

Related: OS#3803
Change-Id: I3d71c66f8c401f5afbad9b1c86c24580dab9e0ce
diff --git a/tests/testsuite.at b/tests/testsuite.at
index a043f0c..c231b96 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -126,6 +126,12 @@
 AT_CHECK([$abs_top_builddir/tests/lapd/lapd_test], [0], [expout], [ignore])
 AT_CLEANUP
 
+AT_SETUP([gsm0502])
+AT_KEYWORDS([gsm0502])
+cat $abs_srcdir/gsm0502/gsm0502_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/gsm0502/gsm0502_test], [0], [expout], [ignore])
+AT_CLEANUP
+
 AT_SETUP([gsm0808])
 AT_KEYWORDS([gsm0808])
 cat $abs_srcdir/gsm0808/gsm0808_test.ok > expout