aper_put_nsnnwn() and aper_get_nsnnwn() were wrong. All the places
where they were used are modified, if needed.

The functions aper_get_constrained_whole_number() and
aper_put_constrained_whole_number() are introduced.
They don't cover all cases, very big numbers are not supported.

The sample ASN.1 file and C program at the end show some issues.

For sequence-of, APER decoding fails and the XER output after
APER encode/decode is:

-----------
xer after encode/decode:
<ListOfInt>
    <INTEGER>1</INTEGER>
    <INTEGER>259</INTEGER>
</ListOfInt>
-----------

instead of:

-----------
xer after encode/decode:
<ListOfInt>
    <INTEGER>1</INTEGER>
    <INTEGER>2</INTEGER>
    <INTEGER>3</INTEGER>
</ListOfInt>
-----------

For the enum test, we have:

-----------
aper ue lost[1]: d4
-----------

instead of:

-----------
aper ue lost[1]: 95
-----------

And APER decoding fails.

For the choice test, we see:

-----------
aper snssai[3]: 80 01 00
-----------

instead of:

-----------
aper snssai[3]: 84 01 00
-----------

And XER after encode/decode is wrong.

To generate C code from the ASN.1 file, asn1c is run as:
asn1c -pdu=all -fno-include-deps -fcompound-names -gen-UPER -no-gen-BER -no-gen-JER -no-gen-OER -gen-APER -no-gen-example

ASN.1 file:

-----------
Test DEFINITIONS AUTOMATIC TAGS ::=

BEGIN

TestCond-Type ::= CHOICE{
        gBR                                     ENUMERATED {true, ...},
        aMBR                            ENUMERATED {true, ...},
        isStat                          ENUMERATED {true, ...},
        isCatM                          ENUMERATED {true, ...},
        rSRP                            ENUMERATED {true, ...},
        rSRQ                            ENUMERATED {true, ...},
        ...,
        ul-rSRP                         ENUMERATED {true, ...},
        cQI                                     ENUMERATED {true, ...},
        fiveQI                          ENUMERATED {true, ...},
        qCI                                     ENUMERATED {true, ...},
        sNSSAI                          ENUMERATED {true, ...}
}

CauseRadioNetwork ::= ENUMERATED {
        handover-desirable-for-radio-reasons,
        time-critical-handover,
        resource-optimisation-handover,
        reduce-load-in-serving-cell,
        partial-handover,
        unknown-new-eNB-UE-X2AP-ID,
        unknown-old-eNB-UE-X2AP-ID,
        unknown-pair-of-UE-X2AP-ID,
        ho-target-not-allowed,
        tx2relocoverall-expiry,
        trelocprep-expiry,
        cell-not-available,
        no-radio-resources-available-in-target-cell,
        invalid-MME-GroupID,
        unknown-MME-Code,
        encryption-and-or-integrity-protection-algorithms-not-supported,
        reportCharacteristicsEmpty,
        noReportPeriodicity,
        existingMeasurementID,
        unknown-eNB-Measurement-ID,
        measurement-temporarily-not-available,
        unspecified,
        ...,
        load-balancing,
        handover-optimisation,
        value-out-of-allowed-range,
        multiple-E-RAB-ID-instances,
        switch-off-ongoing,
        not-supported-QCI-value,
        measurement-not-supported-for-the-object,
        tDCoverall-expiry,
        tDCprep-expiry,
        action-desirable-for-radio-reasons,
        reduce-load,
        resource-optimisation,
        time-critical-action,
        target-not-allowed,
        no-radio-resources-available,
        invalid-QoS-combination,
        encryption-algorithms-not-supported,
        procedure-cancelled,
        rRM-purpose,
        improve-user-bit-rate,
        user-inactivity,
        radio-connection-with-UE-lost,
        failure-in-the-radio-interface-procedure,
        bearer-option-not-supported,
        mCG-Mobility,
        sCG-Mobility,
        count-reaches-max-value,
        unknown-old-en-gNB-UE-X2AP-ID,
        pDCP-Overload
}

ListOfInt ::= SEQUENCE (SIZE (3)) OF INTEGER

END
-----------

C program:

-----------

void test(void *v, int is_aper, char *name, void *t)
{
  unsigned char b[128];
  asn_enc_rval_t r = asn_encode_to_buffer(NULL,
                       is_aper ? ATS_ALIGNED_BASIC_PER
                               : ATS_UNALIGNED_BASIC_PER,
                       t, v, b, sizeof(b));
  if (r.encoded <= 0) printf("error\n"); else printf("ok\n");
  printf("%s %s[%ld]:", is_aper ? "aper" : "uper", name, r.encoded);
  for (int i = 0; i < r.encoded; i++) printf(" %2.2x", b[i]);
  printf("\n");

  void *ret = NULL;
  asn_dec_rval_t d = asn_decode(NULL,
                       is_aper ? ATS_ALIGNED_BASIC_PER
                               : ATS_UNALIGNED_BASIC_PER,
                       t, &ret, b, r.encoded);
  if (d.consumed != r.encoded) printf("error\n"); else printf("ok\n");
  printf("xer of input:\n");
  xer_fprint(stdout, t, v);
  printf("xer after encode/decode:\n");
  xer_fprint(stdout, t, ret);
}

int main(void)
{
  /* test sequence of */
  ListOfInt_t l = { 0 };
  long val[3] = { 1, 2, 3 };
  asn_sequence_add(&l.list, &val[0]);
  asn_sequence_add(&l.list, &val[1]);
  asn_sequence_add(&l.list, &val[2]);
  test(&l, 1, "sequence-of (size 3)", &asn_DEF_ListOfInt);
  test(&l, 0, "sequence-of (size 3)", &asn_DEF_ListOfInt);

  /* test enum */
  CauseRadioNetwork_t v;
  v = CauseRadioNetwork_radio_connection_with_UE_lost;

  test(&v, 1, "ue lost", &asn_DEF_CauseRadioNetwork);
  test(&v, 0, "ue lost", &asn_DEF_CauseRadioNetwork);

  v = CauseRadioNetwork_cell_not_available;

  test(&v, 1, "no cell", &asn_DEF_CauseRadioNetwork);
  test(&v, 0, "no cell", &asn_DEF_CauseRadioNetwork);

  /* test choice */
  TestCond_Type_t w;
  w.present = TestCond_Type_PR_sNSSAI;
  w.choice.sNSSAI = TestCond_Type__sNSSAI_true;

  test(&w, 1, "snssai", &asn_DEF_TestCond_Type);
  test(&w, 0, "snssai", &asn_DEF_TestCond_Type);

  w.present = TestCond_Type_PR_gBR;
  w.choice.sNSSAI = TestCond_Type__gBR_true;

  test(&w, 1, "gbr", &asn_DEF_TestCond_Type);
  test(&w, 0, "gbr", &asn_DEF_TestCond_Type);

  return 0;
}
-----------