structure issue

[marcus]

I find the Mikrobasic compiler is padding structures with useless bytes, making the structure larger than it is. For example:

Code: Select all

structure str
  dim a as word '2
  dim b as word '2
  dim c as byte '1
  dim d as byte '1
  dim e as longword  '4
end structure

dim arr as str[3]

for i = 0 to 3
    arr[i].a = 0xAAAA
    arr[i].b = 0xBBBB
    arr[i].c = 0xCC
    arr[i].d = 0xDD
    arr[i].e = 0xEEEEEEEE
next i

'send arr out of serial port - result:
'AA AA BB BB CC DD 00 00 EE EE EE EE 
'AA AA BB BB CC DD 00 00 EE EE EE EE 
'AA AA BB BB CC DD 00 00 EE EE EE EE

What are the "00 00" in the middle of the struct? Is this a bug or feature? If it's a feature, can you please tell me what to expect.

[filip]

Hi,

Please, can you tell me which MCU and compiler version are you using ?

Regards,
Filip.

[marcus]

Hi Filip, the MCU is PIC32MZ2048EFM064 and the compiler is v4.0

[filip]

Hi,

Can you please send the UART part of the code ?

Regards,
Filip.

[marcus]

Code: Select all

sub procedure SerOutN(dim p as ^byte, dim l as word)
    dim w as word
    for w = 1 to l
        UART3_write(p^)
        p = p + 1
    next w
end sub

SerOutN(@arr,36)

[filip]

Hi,

Because the structure members are of different type, the compiler, when it gets to the "d" member, will allocate it on the odd address and then add zeros at next two consecutive addresses,
in order to allocate the last member (longword) at the address dividable by 4 (alignment 4, please look in the PIC32 Specifics chapter of help file).

The solution for your situation would be to print the structure not address by address, but as a structure member (field) instead.

Regards,
Filip.