'-align' option Question

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Daniel Popu 2015-3-25

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https://ww2.mathworks.cn/matlabcentral/answers/186246-align-option-question

Hello,

I have some open points regarding the usage of ‘-align’ option (I set it in Configuration/ Advanced Settings options for a project):

Question 1: Is this ‘-align’ setting affecting only the storage units inside of a struct Or Is it also overriding the alignment value checked in “Target processor type” options?

Question 2: How is the alignment inside a struct - forced with a bitfield_t xxx :0 construct- interpreted? see sample code below start at next: a)byte; b) int c) as specified by ‘-align’ d) alignment option for the mcu ?

Settings used: -Char 8bits signed, Short 16bits, Int 16bits. - Endianess: Little endian. -Alignment: 32 bits. -Target OS: no-predefined-os. Advanced setting used: -align 8

Sample Code: typedef unsigned int bitfield_t;

union sfrByte_t { int value; struct { bitfield_t bit0 : 3; bitfield_t xxx :0; bitfield_t bit1 : 1; bitfield_t bit7 : 1; } byteFields; } ; union sfrByte_t sfrByte;

void f () { unsigned short var1; sfrByte.value = 0x5A; var1 = sfrByte.byteFields.bit1;

}

void main() { f(); }

Thank you for your kind support, Daniel