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  1. #include <iostream>
  2. #include <netinet/in.h>
  3. #include <stdint.h>
  4. using namespace std;
  5.  
  6. using u32=uint32_t;
  7. typedef u32 mpls_label_t;
  8.  
  9. typedef struct {
  10.     /* Label: top 20 bits [in network byte order] */
  11.     /* Experimental: 3 bits ... */
  12.     /* S (bottom of label stack): 1 bit */
  13.     /* TTL: 8 bits */
  14.     mpls_label_t label_exp_s_ttl;
  15. } mpls_unicast_header_t;
  16.  
  17.  
  18. #define MPLS_ENTRY_LABEL_SHIFT 12
  19. #define MPLS_ENTRY_EOS_SHIFT   8
  20.  
  21. #define MPLS_ENTRY_EOS_MASK    0x01    /* EOS bit in its byte */
  22. #define        MPLS_ENTRY_EOS(mpls)    \
  23.     (((mpls) >> MPLS_ENTRY_EOS_SHIFT) & MPLS_ENTRY_EOS_MASK)
  24.  
  25. static inline u32 vnet_mpls_uc_get_s (mpls_label_t label_exp_s_ttl)
  26. {
  27.     return (MPLS_ENTRY_EOS(label_exp_s_ttl));
  28. }
  29.  
  30.  
  31. static inline u32 vnet_mpls_uc_get_label (mpls_label_t label_exp_s_ttl)
  32. {
  33.     return (label_exp_s_ttl>>MPLS_ENTRY_LABEL_SHIFT);
  34. }
  35.  
  36. int main() {
  37. 	auto label_exp_s_ttl = 0xFFA10100;
  38.     cout << "s_ttl:" <<  label_exp_s_ttl << endl;
  39.  
  40.     auto label = ntohl(label_exp_s_ttl);
  41.     auto part1 = (vnet_mpls_uc_get_label(label) << 1);
  42.     cout << "part1:" <<  part1 << endl;
  43.     auto part2 = vnet_mpls_uc_get_s(label);
  44.     cout << "part2:" <<  part2 << endl;
  45.     auto key = (vnet_mpls_uc_get_label(label) << 1) | vnet_mpls_uc_get_s(label);
  46.     cout << "label:" <<  label << endl;
  47.     cout << "key:" <<  key << endl;
  48.  
  49. 	return 0;
  50. }
Success #stdin #stdout 0s 5324KB
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stdin
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Standard input is empty
stdout
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s_ttl:4288741632
part1:52
part2:1
label:107007
key:53
https://ideone.com/aehIGu
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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