From faf1f64a2d0a54d37616a8bec8691346ab792cde Mon Sep 17 00:00:00 2001 From: Holger Hans Peter Freyther Date: Thu, 23 Jun 2011 17:53:27 -0400 Subject: gprs: Honor GSM 04.64 8.4.2 Receipt of unacknowledged information GSM 04.64 8.4.2 asks to ignore UI frames if the DLCI is not known, or if the "(V(UR)- 32) <= N(U) < V(UR)". E.g. if we want to have V(UR) == 511 and this frame is dropped, we would ignore N(U)'s 0 to 510. Calculate the delta. The code is based on Jonathan Santos's "LLC UI window" fix but the issue was discovered independly. --- openbsc/tests/gprs/gprs_test.c | 51 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 openbsc/tests/gprs/gprs_test.c (limited to 'openbsc/tests/gprs/gprs_test.c') diff --git a/openbsc/tests/gprs/gprs_test.c b/openbsc/tests/gprs/gprs_test.c new file mode 100644 index 000000000..7b0e64113 --- /dev/null +++ b/openbsc/tests/gprs/gprs_test.c @@ -0,0 +1,51 @@ +#include +#include +#include + +#include + +#define ASSERT_FALSE(x) if (x) { printf("Should have returned false.\n"); abort(); } +#define ASSERT_TRUE(x) if (!x) { printf("Should have returned true.\n"); abort(); } + +/** + * GSM 04.64 8.4.2 Receipt of unacknowledged information + */ +static int nu_is_retransmission(uint16_t nu, uint16_t vur) +{ + int ret = gprs_llc_is_retransmit(nu, vur); + printf("N(U) = %d, V(UR) = %d => %s\n", nu, vur, + ret == 1 ? "retransmit" : "new"); + return ret; +} + +static void test_8_4_2() +{ + printf("Testing gprs_llc_is_retransmit.\n"); + + ASSERT_FALSE(nu_is_retransmission(0, 0)); + ASSERT_TRUE (nu_is_retransmission(0, 1)); + + /* expect 1... check for retransmissions */ + ASSERT_TRUE (nu_is_retransmission(0, 1)); + ASSERT_TRUE (nu_is_retransmission(511, 1)); + ASSERT_TRUE (nu_is_retransmission(483, 1)); + ASSERT_TRUE (nu_is_retransmission(482, 1)); + ASSERT_FALSE(nu_is_retransmission(481, 1)); + + /* expect 511... check for retransmissions */ + ASSERT_FALSE(nu_is_retransmission(0, 240)); // ahead + ASSERT_FALSE(nu_is_retransmission(0, 511)); // ahead + ASSERT_FALSE(nu_is_retransmission(1, 511)); // ahead + ASSERT_FALSE(nu_is_retransmission(511, 511)); // same + ASSERT_TRUE (nu_is_retransmission(510, 511)); // behind + ASSERT_TRUE (nu_is_retransmission(481, 511)); // behind + ASSERT_FALSE(nu_is_retransmission(479, 511)); // wrapped +} + +int main(int argc, char **argv) +{ + test_8_4_2(); + + printf("Done.\n"); + return EXIT_SUCCESS; +} -- cgit v1.2.3