Debugger watch - structure bitfield adresses and content

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Tomas Hamouz

• June 12, 2023 11:04

Crossworks 4.10.3

I have a structure with bitfields. In debugger watch window, all bitfields are displayed with wrong address, equal base address of the structure. When I change the content of the first field (sum_depth in this case), only the spare0 field (unsigned spare0:4) reads new data, the rest (specified as bool xxx:1) keep to read false.

See the screenshot and structure definition below.

Tomas

 

typedef struct {
    uint64_t        sum_depth;  
    t_cns_data      cns_data;  
    float           surface_pressure;
    t_time_short    average_start;
    uint16_t        bookmark;         
    t_datim         dive_start;         
    t_datim         free_start;         
    tDiveHandle     log_handle;   
    float           sp;                    
    bool            screen_reverse:1;
    bool            auto_SPhigh_set:1;
    bool            not_pressure_test:1;
    bool            manual_gf_switch:1;
    unsigned        spare0:4;              
    t_mode          original_mode;      
    t_time_short    stack_time;         
} t_global_saved;

 

 

 

 

 

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  Michael Johnson

  • June 12, 2023 12:21

  Try expanding the Address column - it will show the bitfield sizes.

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  Tomas Hamouz

  • June 12, 2023 12:46

  Hello,

  see attached screenshot. It seems the bitfield sizes are completely incorrect  - spare0 is 4 bits, the Size column reads 4 bytes. And bool types are all 0 bytes.

  Tomas

  

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  Michael Johnson

  • June 12, 2023 12:51

  Please supply definitions of

  t_cns_data
  t_time_short
  t_datim
  tDiveHandle
  t_mode

  is it a c or cpp file?

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  Tomas Hamouz

  • June 12, 2023 14:25

  Here you are

  The file is a C++ file.

  #define _packed  __attribute__((packed))

  typedef struct {
      double          cns;              
      t_datim         last_cns;    
  } _packed t_cns_data;   

  typedef uint16_t  t_time_short;   

  typedef uint32_t  t_datim;     

  typedef   uint32_t  tDiveHandle;

  typedef enum {
      MODE_SURFACE, 
      MODE_OC,          
      MODE_FREE, 
      MODE_CCR,   
  } _packed t_mode;

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  Michael Johnson

  • June 14, 2023 09:49

  Are you using clang or gcc?

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  Tomas Hamouz

  • June 14, 2023 09:58

  This issue is using clang.

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  Michael Johnson

  • June 14, 2023 09:59

  Yes I can reproduce - thanks.

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  Michael Johnson

  • June 15, 2023 06:34

  Can you see if this

  http://www.rowleydownload.co.uk/snapshots/arm_crossworks_v4_win_x64_setup.exe

  fixes it?

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  Tomas Hamouz

  • June 15, 2023 07:42

  Yes, it fixes the problem, thanks.

  There remains a small cosmetic problem, the Size column shows size of the base type, not the size of the bitfield.There is a discrepancy between size and address columns for bitfields, the Address and Size do not match.

   

   

   

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  Michael Johnson

  • June 15, 2023 07:50

  That's the size of the underlying data type of the bitfield i.e. the data size the compiler will perform to load/store. Quite useful that it looks wrong/odd...

  If you want "spare0:4" to be byte sized then make it

  unsigned char spare0:4

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