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所以我正在開發一個BACnet自動控制系統，我對它比較陌生，因爲這是我第一次使用BACnet。我已經使用asn1c編譯器將ASN.1協議轉換爲C格式。我有一個非常困難的時間找到一個清楚的例子，如何實現代碼的原因有很多。 1，我不完全確定ASN.1是如何工作的，2，現在代碼已經轉換爲C，它看起來截然不同，並且物理語法讓我感到困惑。我想知道是否有人能夠解釋ASN.1傳輸數據的實際過程。我讀過使用ASN.1的手機可以與超級計算機進行通信的情況，我想知道如何以及如果任何人有一個明確的「白癡證明」如何實際解碼和編碼可以從BACnet消息讀取和寫入的消息。下面我發佈了BACnetObjectIdentifierBACnet編碼/解碼ASN.1/C語法
#include "BACnetObjectIdentifier.h"
main()
{
int
BACnetObjectIdentifier_constraint(asn_TYPE_descriptor_t *td, const void
asn_app_constraint_failed_f *ctfailcb, void *app_key) {
const OCTET_STRING_t *st = (const OCTET_STRING_t *)sptr;
size_t size;
if(!sptr) {
_ASN_CTFAIL(app_key, td, sptr,
"%s: value not given (%s:%d)",
td->name, __FILE__, __LINE__);
return -1;
}
size = st->size;
if((size == 4)) {
/* Constraint check succeeded */
return 0;
} else {
_ASN_CTFAIL(app_key, td, sptr,
"%s: constraint failed (%s:%d)",
td->name, __FILE__, __LINE__);
return -1;
}
}
static void
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(asn_TYPE_descriptor_t *td) {
td->free_struct = asn_DEF_OCTET_STRING.free_struct;
td->print_struct = asn_DEF_OCTET_STRING.print_struct;
td->check_constraints = asn_DEF_OCTET_STRING.check_constraints;
td->ber_decoder = asn_DEF_OCTET_STRING.ber_decoder;
td->der_encoder = asn_DEF_OCTET_STRING.der_encoder;
td->xer_decoder = asn_DEF_OCTET_STRING.xer_decoder;
td->xer_encoder = asn_DEF_OCTET_STRING.xer_encoder;
td->uper_decoder = asn_DEF_OCTET_STRING.uper_decoder;
td->uper_encoder = asn_DEF_OCTET_STRING.uper_encoder;
if(!td->per_constraints){
td->per_constraints = asn_DEF_OCTET_STRING.per_constraints;
td->elements = asn_DEF_OCTET_STRING.elements;
td->elements_count = asn_DEF_OCTET_STRING.elements_count;
td->specifics = asn_DEF_OCTET_STRING.specifics;
}
void
BACnetObjectIdentifier_free(asn_TYPE_descriptor_t *td,
void *struct_ptr, int contents_only) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
td->free_struct(td, struct_ptr, contents_only);
}
int
BACnetObjectIdentifier_print(asn_TYPE_descriptor_t *td, const void *struct_ptr,
int ilevel, asn_app_consume_bytes_f *cb, void *app_key) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->print_struct(td, struct_ptr, ilevel, cb, app_key);
}
asn_dec_rval_t
BACnetObjectIdentifier_decode_ber(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
void **structure, const void *bufptr, size_t size, int tag_mode) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->ber_decoder(opt_codec_ctx, td, structure, bufptr, size, tag_mode);
}
asn_enc_rval_t
BACnetObjectIdentifier_encode_der(asn_TYPE_descriptor_t *td,
void *structure, int tag_mode, ber_tlv_tag_t tag,
asn_app_consume_bytes_f *cb, void *app_key) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->der_encoder(td, structure, tag_mode, tag, cb, app_key);
}
asn_dec_rval_t
BACnetObjectIdentifier_decode_xer(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
void **structure, const void *bufptr, size_t size, int tag_mode) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->ber_decoder(opt_codec_ctx, td, structure, bufptr, size, tag_mode);
}
asn_enc_rval_t
BACnetObjectIdentifier_encode_der(asn_TYPE_descriptor_t *td,
void *structure, int tag_mode, ber_tlv_tag_t tag,
asn_app_consume_bytes_f *cb, void *app_key) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->der_encoder(td, structure, tag_mode, tag, cb, app_key);
}
asn_dec_rval_t
BACnetObjectIdentifier_decode_xer(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
void **structure, const char *opt_mname, const void *bufptr, size_t size) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->xer_decoder(opt_codec_ctx, td, structure, opt_mname, bufptr, size);
}
asn_enc_rval_t
BACnetObjectIdentifier_encode_xer(asn_TYPE_descriptor_t *td, void *structure,
int ilevel, enum xer_encoder_flags_e flags,
asn_app_consume_bytes_f *cb, void *app_key) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->xer_encoder(td, structure, ilevel, flags, cb, app_key);
}
asn_dec_rval_t
BACnetObjectIdentifier_decode_uper(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
asn_per_constraints_t *constraints, void **structure, asn_per_data_t *per_data) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->uper_decoder(opt_codec_ctx, td, constraints, structure, per_data);
}
asn_enc_rval_t
BACnetObjectIdentifier_encode_uper(asn_TYPE_descriptor_t *td,
asn_per_constraints_t *constraints,
void *structure, asn_per_outp_t *per_out) {
BACnetObjectIdentifier_1_inherit_TYPE_descriptor(td);
return td->uper_encoder(td, constraints, structure, per_out);
}
static asn_per_constraints_t asn_PER_type_BACnetObjectIdentifier_constr_1 GCC_NOTUSED = {
{ APC_UNCONSTRAINED, -1, -1, 0, 0 },
{ APC_CONSTRAINED, 0, 0, 4, 4 } /* (SIZE(4..4)) */,
0, 0 /* No PER value map */
};
static ber_tlv_tag_t asn_DEF_BACnetObjectIdentifier_tags_1[] = {
(ASN_TAG_CLASS_APPLICATION | (12 << 2)),
(ASN_TAG_CLASS_UNIVERSAL | (4 << 2))
};
asn_TYPE_descriptor_t asn_DEF_BACnetObjectIdentifier = {
"BACnetObjectIdentifier",
"BACnetObjectIdentifier",
BACnetObjectIdentifier_free,
BACnetObjectIdentifier_print,
BACnetObjectIdentifier_constraint,
BACnetObjectIdentifier_decode_ber,
BACnetObjectIdentifier_encode_der,
BACnetObjectIdentifier_decode_xer,
BACnetObjectIdentifier_encode_xer,
BACnetObjectIdentifier_decode_uper,
BACnetObjectIdentifier_encode_uper,
0, /* Use generic outmost tag fetcher */
asn_DEF_BACnetObjectIdentifier_tags_1,
sizeof(asn_DEF_BACnetObjectIdentifier_tags_1)
/sizeof(asn_DEF_BACnetObjectIdentifier_tags_1[0]) - 1, /* 1 */
asn_DEF_BACnetObjectIdentifier_tags_1, /* Same as above */
sizeof(asn_DEF_BACnetObjectIdentifier_tags_1)
/sizeof(asn_DEF_BACnetObjectIdentifier_tags_1[0]), /* 2 */
&asn_PER_type_BACnetObjectIdentifier_constr_1,
0, 0, /* No members */
0 /* No specifics */
};
}
上面的代碼是asn1c編譯器生成的代碼。任何幫助是極大的讚賞。
我從您使用XER的其他問題中看到。這是另一組標準化的編碼規則。它不是指定一個二進制編碼，而是指定一個文本編碼，它是用XML編碼的。 – Kevin